i

Materials Science and

Engineering Laboratory

FY 2003 Programs and

Accomplishments

Metallurgy

Division

Carol A. Handwerker, Chief

Frank W. Gayle, Deputy

NISTIR 7017

September 2003

National Institute of

Standards and Technology

Arden L. Bement, Jr.

Director

Technology

Administration

Phillip J. Bond

Undersecretary of

Commerce for Technology

U.S. Department

of Commerce

Donald L. Evans

Secretary
ii
iii

Table of Contents

Table of Contents

Executive Summary ...................................................................................................................1

Technical Highlights...................................................................................................................3

Solidification in the Presence of Impurities:

Phase Field Simulations of the Growth of “Dizzy” Dendrites ............................................4

Advanced Metallizations for Sub-100 nm Electronics ........................................................6

High Throughput Data Analysis of Multicomponent

Multiphase Diffusion Data ..................................................................................................8

Modeling Dynamics, Damping and Defects for Perpendicular

Magnetic Recording Media ...............................................................................................10

Artifacts in Ballistic Magnetoresistance Measurements ..................................................12

Phase Field Modeling of the Electrochemical Interface ...................................................14

NEMI–NIST–TMS Workshop on Tin Whiskers: Cause and Effect ...............................16

Kolsky Bar: Materials Properties at High Strain Rates and

High Heating Rates...........................................................................................................18

Advanced Manufacturing Methods .........................................................................................20

Anelasticity and Springback Predictability ........................................................................21

Microstructural Origins of Surface Roughening and

Strain Localizations ...........................................................................................................22

Plasticity, Fabrication Processes, and Performance .........................................................23

Standard Tests and Data for Sheet Metal Formability .....................................................24

Underlying Processes of Plastic Deformation in Metal Alloys ........................................25

Atomization Processing — Recommended Practices ......................................................26

High Speed Machining ......................................................................................................27

Phase Field Modeling of the Electrochemical Interface ...................................................28

Processing of Amorphous Metals .....................................................................................29

Combinatorial Methods............................................................................................................ 30

Combinatorial Methods for Thin Films .............................................................................31

Phase Diagrams for III–V Thin Films and Metal Contacts .............................................32

Data and Data Delivery ..........................................................................................................33

Informatics and Visualization in Materials Data Delivery ................................................34

Reaction Path Analysis in Multicomponent Systems ........................................................35
iv

Table of Contents

Nanocharacterization ...............................................................................................................36

Bridging Length Scales in Theory and Modeling:

Microstructure Evolution and Material Mechanics........................................................... 37

Electrochemical Processing of Nanoscale Materials ....................................................... 38

Interface of Materials with Biology ........................................................................................ 39

Biocompatibility of Metals Reference Powders ...............................................................40

Materials for Micro- and Opto-Electronics ............................................................................. 41

Superconformal Film Growth: Measurement and Modeling ............................................ 42

Lead-free Surface Finishes: Tin Whisker Growth ........................................................... 43

Lead-Free Solders and Solderability ................................................................................. 44

Magnetic Properties and Standard Reference Materials ................................................. 45

Magnetic Properties of Nanostructured Materials ........................................................... 46

Nanomagnetodynamics ..................................................................................................... 47

Anomalously Large Low Temperature Intermixing in

Metallic Thin Films............................................................................................................ 48

Materials Property Measurements .......................................................................................... 49

Analysis of Structural Steel in the World Trade Center....................................................50

Hardness Standardization: Rockwell, Vickers, Knoop ..................................................... 51

Marine Forensics and Preservation of Historic Shipwrecks ............................................ 52

Materials Structure Characterization ...................................................................................... 53

Nanoscale Characterization by Electron Microscopy....................................................... 54

USAXS Imaging: Microscope Development and Validation ...........................................55

Metallurgy Division FY03 Annual Report Publication List ..................................................... 57

Metallurgy Division .................................................................................................................. 65

Research Staff......................................................................................................................... 66

Organizational Charts .............................................................................................................. 69
1

Executive Summary

Executive Summary

This Annual Report describes the major technical

activities, accomplishments, and areas of scientific

expertise in the Metallurgy Division of NIST Materials

Science and Engineering Laboratory for FY2003

(October 2002 through September 2003). Through this

report, we provide some insight into how our research

programs meet the needs of our customers, how the

capabilities of the Metallurgy Division are being used to

solve problems important to the national economy and

the materials metrology infrastructure, and how we

interact with our customers to establish new priorities

and programs. Contact information for our staff is

provided if you would like to participate in any of these

projects or if have any questions. We also welcome

feedback and suggestions on how we can better serve

the needs of our customers and encourage increasing

collaboration to this end.

Mission of the NIST Metallurgy Division

Our mission is to provide critical leadership in the

development of measurement methods, standards,

and fundamental understanding of materials behavior

needed by U.S. materials users and producers to

become or remain competitive in the changing global

marketplace.

As a fundamental part of this mission, we are

responsible not only for developing new measurement

methods with broad applicability across materials

classes and industries but also for working with

individual industry groups to develop and integrate

measurements, standards, software tools, and

evaluated data for specific, technologically important

applications.

Establishing Priorities

We examine a wide range of research opportunities

and make choices for our research portfolio based on:

the match to the NIST mission, the magnitude and

immediacy of industrial need, whether the NIST

contribution is critical for success, the anticipated

impact relative to our investment, our ability to

respond in a timely fashion with high-quality output,

and the opportunity to advance mission science.

This requires us to establish our research priorities

through extensive consultation and collaboration

with our customers in U.S. industry and with

our counterparts in the international metrology

community using a variety of methods including

industrial roadmapping activities, workshops,

technical meetings, standards committee participation,

and individual consultation with our customers.

For us to have the highest possible impact also

requires that we work to be at the forefront of

materials science.

Within the context of industrial relevance and potential

impact of our research, technology trends strongly

influence the technical directions addressed by NIST.

We prefer to work in rapidly evolving technologies,

where advances in measurement science are needed

to understand the limitations on system behavior and,

therefore, where our contributions are likely to have

an impact on the course of technology. For NIST as

a whole and the Metallurgy Division in particular, we

are committed to having an impact on the measurement

and standards infrastructure for nanotechnology, health

care, and homeland security. Nanotechnology is not

an industry sector itself but will have an impact on

present and future industrial enterprises. Three new

Division projects began in nanotechnology and health

care in 2003; an additional project on Informatics and

Visualization in Data Delivery was started in 2003 to

examine how to best transfer our results to traditional

and possible NIST customers. In 2004, we will begin

two new nanotechnology projects selected through a

NIST-wide competition. In collaboration with three

other NIST laboratories (EEEL, ITL, PL), a major

project will be started on Nanoscale Engineered

Sensors for Ultra-low Magnetic Field Metrology.

Low noise, ultra-low magnetic field sensors could

have a significant impact on healthcare diagnostics,

homeland security sensors, and magnetic data storage.

In collaboration with three other NIST laboratories

(CSTL, PL, and ITL), we will begin developing

systems for three-dimensional chemical imaging at

the nanoscale in the transmission electron microscope.

This should add greatly to our understanding of

the relationship between materials composition,

processing, and properties, the raison d’etre of

materials science and engineering. These were the only

two fully funded projects in the NIST competition.

Research Portfolio

Our 2003 research portfolio focuses on fulfilling

specific measurement needs of the industrial

sectors: the magnetic data storage, microelectronics/

optoelectronics, automotive, aerospace, and defense

industries, and on developing the materials data need

for the World Trade Center failure investigation.

Our output consists of a variety of forms, from a

fundamental understanding of materials behavior

to measurement techniques conveyed through the

scientific literature and oral presentations, standard

reference materials, evaluated data and online

databases, software tools, and sensors for on-line

process control. Examples of our 2003 outputs in

a few of these areas are:

■ Magnetic Data Storage: In 2003, we shifted our

emphasis from Giant Magnetoresistance (GMR)

in Thin Films to understanding artifacts in Ballistic

Magnetoresistance (BMR). In the past year, advances
2

Executive Summary

in the Ballistic Magnetoresistance (BMR) effect

appeared to provide an enormous increase in the

sensitivity of nanoscale devices. The scientific press

reported the creation of devices with resistance changes

as much as 106 as one of the major discoveries of

the year. Experiments at NIST in 2003 have found

that several simple artifacts account for the results.

NIST is taking a leading role in designing artifact-free

metrology to provide reliable data to the magnetic

sensor industry and the academic community.

■ Microelectronics Packaging: In the MSEL

Program on Materials for Microelectronics, we

continue to provide tools for producing improved

metal interconnects, from copper on-chip

interconnects at the nanometer scale to lead-free

solder joints on printed wiring boards. Our project

on measurements and modeling of electrodeposited

copper for nanometer scale chip interconnection

technology continues to produce significant value to

the microelectronics community. Since the beginning

of the project in April 1999, we have developed a

measurement technique, a theory for control of

interface dynamics, and modeling software for

predicting quantitatively the ability of complex

electrolytes to fill vias and trenches, and we extended

the NIST model to electrodeposited metals other than

copper. In 2003, we used our theory as a basis for

developing processing methods to increase the aspect

ratios of fine features (< 50 nm) that can be filled

and have transferred all of these to the appropriate

industrial customers. In addition, in response to the

need for improved seed layer systems articulated

to us by International Sematech, we demonstrated

the utility of thin ruthenium layers as combination

barrier layer/seed layer in superconformal growth

on patterned substrates. In the area of electronics

assembly, our role in the NEMI Lead-Free Solder

Task Force has wound down. With the completion

of Task Force research plan in 2002, and final

analysis of the results in 2003, U.S. microelectronics

companies now have enough critically evaluated data

to decide on whether to implement lead-free solders

in manufacturing. The one open question is how

important tin whiskers forming on plated component

surface finishes will be for system reliability. There

is a long, documented history of tin whiskers causing

catastrophic short circuits in critical systems such as

satellites and medical devices. In the past, Pb-Sn alloys

were plated instead of Sn since Pb additions appeared

to suppress whisker growth. With the requirement of

Pb-free manufacturing in some regions, such as the

European union, Pb additions are no longer acceptable.

NIST has taken a major role in helping NEMI develop

test methods for whisker growth and a fundamental

understanding of the mechanisms leading to whisker

formation.

■ Automotive: Within the sub-program on the

Forming of Lightweight Materials, we are developing

standard test methods for sheet metal forming,

measurements of surface roughness, and physically

based constitutive laws — and measurement tools

needed to reveal them. In FY2003, an x-ray stress

measuring system was installed on the sheet metal

formability station. With this addition, the formability

facility will be capable of direct, in situ measurement

of the stress in a given direction while the sample

is under biaxial load. Such measurements will lead

to a standard test for measuring multiaxial flow

surfaces in sheet metal during stamping operations.

All of our projects in the Forming of Lightweight

Materials Program are performed in close collaboration

with the automotive industry through formal

partnerships, such as USCAR and the Freedom Car,

and are formulated to help accelerate the design of

forming operations for lightweight materials such as

aluminum, that will ultimately improve fuel economy.

■ Infrastructure Materials: NIST has developed a

unique testing facility for measuring high-strain rate

mechanical properties of materials at high heating

rates. Based on the Kolsky bar design (also known

as a split-Hopkinson pressure bar), materials can

be strained at rates as high as 105 s–1 while being

heated up to 1300K at heating rates up to 5x104 K/s.

This facility was initially developed to provide insight

and data for high speed machining of commercial alloys.

In addition to this application, the Kolsky bar facility is

providing the rate dependence of plastic deformation

for the many types of structural steel in the World Trade

Center buildings and for projectiles such as those used

as military tank penetrators. We expect the facility to

be useful in the future for development of data and

modeling in the areas of dynamic fracture and crack

arrest of high strength pipeline steels, bullets and body

armor for the Office of Law Enforcement Standards,

and additional issues in manufacturing.

Division Structure and Expertise

The Division is composed of 39 scientists, supported

by 6 technicians, 6 administrative staff members,

and more than 80 guest scientists, and it’s organized

into five groups that represent the Division’s core

expertise in Metallurgical Processing, Electrochemical

Processing, Magnetic Materials, Materials Structure

and Characterization, and Materials Performance.

However, by virtue of the interdisciplinary nature of

materials problems in the industrial and metrology

sectors that we serve, Program teams are assembled

across group, division and laboratory boundaries and,

in most cases, with academic and industrial partners,

to best meet our project goals. We are committed to

assembling the expertise and resources to fulfill our

technical goals with the speed and quality necessary

to have the desired impact. We welcome your

participation with us in this enterprise.

Carol A. Handwerker, Division Chief

Frank W. Gayle, Deputy Division Chief
3

Technical Highlights

Technical Highlights

The following Technical Highlights section includes

expanded descriptions of research projects that have

broad applicability and impact. These projects generally

continue for several years. The results are the product

of the efforts of several individuals. The Technical

Highlights include:

■ Solidification in the Presence of Impurities:

Phase Field Simulations of the Growth of “Dizzy”

Dendrites

■ Advanced Metallizations for Sub-100 nm Electronics

■ High Throughput Data Analysis of Multicomponent

Multiphase Diffusion Data

■ Modeling Dynamics, Damping and Defects for

Perpendicular Magnetic Recording Media

■ Artifacts in Ballistic Magnetoresistance

Measurements

■ Phase Field Modeling of the Electrochemical Interface

■ NEMI–NIST–TMS Workshop on Tin Whiskers:

Cause and Effect

■ Kolsky Bar: Materials Properties at High Strain Rates

and High Heating Rates
4

Technical Highlights

Solidification in the Presence of Impurities:

Phase Field Simulations of the Growth of “Dizzy” Dendrites

Figure 1: The growing PEO-PMMA polymer dendrite on the

left exhibits the four symmetry of the underlying crystal, while the

phase field simulation on the right shows striking similarities in

its growth form.

polymer blend (PEO-PMMA) crystallizing in a dendritic

pattern with four main branches and a network of

fine side branches. The phase field simulation on the

right matches this growth form quite well. While the

simulations are two-dimensional, the polymer films are

thin enough that this is a reasonable approximation.

While such dendritic growth patterns are common,

under certain circumstances dendrites can grow which

appear to not reflect the underlying crystallographic

symmetries, and often, the branches of these dendrites

curve in a seemingly erratic fashion. We have termed

these growth structures “dizzy dendrites,” and two

exemplary experimental results are shown in Figures 2a

Classical studies of solidification consider the growth

of a crystal from a nucleus, and, in the absence of other

effects, this crystal will have a single crystallographic

orientation. Thus, as is shown in Figure 1, symmetry

reflecting the underlying four-fold crystal-lattice

symmetry is evinced in the growth shape. Indeed,

the left figure shows the growth of an undercooled

It is beyond the capacity of conventional models

of solidification to describe and predict the

formation and growth of polycrystalline

structures. With the NIST development of a new

phase field model of polycrystals, entire classes

of microstructure are now subject to study not

only within the confines of the laboratory but also

the theoretician’s computer. This computational

tool offers unprecedented control in the design

of crystalline and semi-crystalline material.

James A. Warren and Jack Douglas

During solidification, materials do not freeze in

 a uniform manner, except under very special

circumstances. Instead, a whole host of patterns

emerges, of which the snowflake is the most familiar.

The snowflake is not unique to water, however,

as nearly all materials can solidify having such a

pattern, and this process is referred to as dendritic

growth. Dendrites, Latin for “trees,” are ubiquitous in

solidification and occur in situations from commercial

castings to frost on a windshield.

Figure 2: The growing PEO-PMMA polymer dendrites in the

upper two images exhibit what we have termed dizzy dendritic

growth. The simulation in the lower image is again provocatively

similar in its growth form.

a. b.

c.
5

Technical Highlights

and 2b. One of the keys to the creation of such

growth structures is the presence of clay nucleating

agents in the polymer blend, and it has been

hypothesized (based on the observation of dendrite

tip deflection as it traversed such an impurity) that

the presence of these nucleating agents was causing

the observed “dizziness.”

However, the very fact that the dendrite no

longer reflects the symmetry of the underlying crystal

immediately requires that the dendrite no longer be a

single crystal, and, thus, a more complex phase field

model which incorporates multiple grain orientations

is required if we are to describe and predict this

interesting phenomenon.

Over the past few years, Metallurgy Division

scientists, in collaboration with researchers at MIT

and Hokkaido University, have developed a phase

field model that extends the models of solidification to

include polycrystalline growth. As is often the case

in scientific research, the ultimate uses of this model

are not those necessarily anticipated by the model

developers. In this case, researchers at the Research

Institute for Solid State Physics and Optics in Budapest

collaborated with NIST scientists to harness this model

to explain the observed dizzy dendrites.

Specifically, we have postulated the presence of

impurities that, upon incorporation into the solidifying

crystal, may cause the creation of a grain boundary.

We modeled these impurities by assuming a small

region of space has a crystal orientation that is fixed

(or has a predetermined orientation as a function of

time). We refer to these regions of fixed orientation

as pinning centers. Among the many interesting

observations found during the evaluation of this

model, by numerical experiments, we observed that

the dendrites would not typically deflect from their

original trajectory unless the tip of the growing stalk

crossed very near a pinning center. Studies were also

made of the sensitivity of the deflection as a function

of the size and misorientation of the pinning center.

Finally, we considered a random orientation distribution

at a density chosen to be the same as the experimental

value for clay nucleating agents in the PEO/ PMMA

experiments shown in Figure 2. When the simulation

was performed, the microstructure had a strong

resemblance to experimental observations, as is seen

in Figure 2c.

Having successfully modeled the growth of

this complex pattern, we now are investigating the

possibility of using our increased understanding of

these systems to control the types of microstructure

that can be created. With that in mind, we explored

how the manipulation of included pinning centers

can influence the growth shape of dendritic patterns.

In Figure 3, we show two such experiments, indicating

both the solute distribution (on the left) as well as the

crystallographic orientation (on the right). In the upper

simulation, we laid down 11 horizontal lines of fixed

orientation. This resulted in a main dendrite stalk

that zigzagged, while changing orientation to reflect

the choices made by the pinning lines. In the lower

simulation, we placed a random distribution of pinning

centers, all of the same orientation, and insisted that

the orientations rotate in time with a fixed frequency.

We imagine that a clever experimental setup could

realize such control using electromagnetic effects or

surface patterning of growth substrates.

For More Information on this Topic

J. Warren (Metallurgy Division, NIST);

Jack Douglas (Polymers Division, NIST);

R. Kobayashi (Hokkaido University, Japan);

L. Granasy (RISSPO, Hungary); W.C. Carter (MIT)

Figure 3: This new phase field model can also be used to predict

methods to control microstructural patterns. The patterns on the

left indicate concentration of solute, while the patterns on the right

indicate the orientation of the crystal. The structures on the top

were induced by laying down horizontal lines of fixed orientation.

This causes the main stalk to zigzag. In the lower figures, we

include orientation pinning centers that spin at a fixed rotation

rate, causing the dendrite to develop a pinwheel structure.
6

Technical Highlights

Advanced Metallizations for Sub-100 nm Electronics

Electrodeposited copper is rapidly replacing

aluminum for on-chip “wiring” because of its

lower electrical resistivity, superior electromigration

behavior, and the ability to fill fine features

without the formation of seams or voids. As

feature dimensions go below 100 nm, difficulties

in maintaining performance are anticipated. We

are addressing these issues through a combination

of modeling and experimental efforts. In FY2003,

we have pushed the quantitative limits of the

Curvature Enhanced Accelerator Coverage (CEAC)

mechanism developed in the Metallurgy Division

of NIST. Exploration of the mechanism has yielded

new electrochemical processing routes for improved

metallization and is guiding the development of

advanced metallizations beyond copper as well

as new processing routes such as ruthenium

barriers for seedless electrodeposition of copper.

Thomas P. Moffat and Daniel Josell

This project is meeting the microelectronics

 industry’s need for improved device metallizations

by exploring advanced materials and process models

for superconformal film growth. In FY2003 we have:

■ Developed a two-step process for obtaining superfill

during silver electrodeposition;

■ Demonstrated superconformal feature filling using

ruthenium barriers without copper seeds;

■ Described an exact solution for feature filling under

conditions of fixed total catalyst coverage;

■ Extended the CEAC mechanism to explain surface

stabilization of planar deposits during deposition of

metals in electrolytes containing surfactant additives;

■ Quantified consumption of adsorbed catalyst

(neglected in previous CEAC models) which can

substantially affect feature filling under certain

deposition conditions.

Technical Details

Filling of trenches and vias with silver and copper

is quantitatively explained by the Curvature Enhanced

Accelerator Coverage Mechanism (CEAC) developed at

NIST. Our current measurement and modeling effort

is focused on copper and silver metallizations, the latter

metal having the lowest resistivity of any element and,

thus, having potential on-chip applications.

A two-step process for superfill of high aspect

ratio features during silver deposition was demonstrated

for the first time. In this process, the catalyst is

adsorbed on the patterned wafer prior to metal

deposition; in traditional copper processing, a single

electrolyte contains both the catalyst and the metal ions.

As explained by the CEAC mechanism, this process

offers the possibility of improved filling of finer features

with higher aspect ratios through minimization of the

conformal “incubation” period of growth. In addition,

the plating bath requires fewer components and is thus

easier to maintain under industrial conditions.

In a review of NIST research by International

Sematech in November 2000, Aaron Frank, Program

Manager for Copper Deposition, requested that we also

examine a growing problem for on-chip interconnects:

poor deposition of seed layers as features shrink.

In response to this request, we demonstrated in

FY 2003 that superconformal electrodeposition

directly on ruthenium barrier layers on patterned

substrates eliminates the difficulties associated with

sputter-depositing copper seeds on tantalum and

titanium nitride barriers, again allowing filling of finer

features with higher aspect ratios (See Figure 1).

Figure 1: Bottom-up copper fill during electrodeposition in

50 nm wide trenches with no copper seed is visible in the top

image. The patterned dielectric with the ruthenium barrier alone

is visible in the bottom image.

Computer codes, that quantitatively predict

superconformal deposition in fine features through the

CEAC mechanism, evaluate concentration fields in the

electrolyte as well as surface coverage of adsorbed

catalyst on a moving boundary. Our closed-form solution

for fixed initial coverage of catalyst can be used to assess

the accuracy of these codes, increasing the reliability of
7

Technical Highlights

Electrochemical and surface analytical measurements

on planar substrates were used in FY2003 to establish

rates of catalyst consumption that affect both feature

filling and, quite likely, the microstructure of the metal

deposits. Previous CEAC-based models have discounted

such consumption, and this work demonstrates the

reasonableness of such assumptions for the previously

studied conditions. It also extends the understanding

of CEAC mechanism operation to the less than ideal

deposition conditions for which catalyst consumption

is significant.

D. Josell, D. Wheeler, C. Witt, and T.P. Moffat.

“Seedless Superfill: Copper Electrodeposition in

Trenches with Ruthenium Barriers.” Electrical and

Solid-State Letters, (in press).

G.B. McFadden, S.R. Coriell, T.P. Moffat,

D. Josell, D. Wheeler, W. Schwarzacher, and J. Mallett.

“A Mechanism for Brightening: Linear Stability Analysis

of the Curvature Enhanced Accelerator Coverage Model.”

J. Electrochem. Soc., (in press).

D. Josell, S. Kim, D. Wheeler, T.P. Moffat, and

S.G. Pyo. “Interconnect Fabrication by Superconformal

Iodine-Catalyzed Chemical Vapor Deposition of Copper.”

J. Electrochem. Soc., 150 (5), C368–C373 (2003).

D. Wheeler, D. Josell, and T.P. Moffat. “Modeling

Superconformal Electrodeposition Using the Level Set

Method.” J. Electrochem. Soc., 150 (5), C302–C310

(2003).

B.C. Baker, C. Witt, D. Wheeler, D. Josell, and

T.P. Moffat. “Superconformal Silver Deposition Using

KSeCN Derivitized Substrates.” Electrochemical and

Solid-State Letters, 6 (5), C67–C69 (2003).

T.P. Moffat, B. Baker, D. Wheeler, and D. Josell.

“Accelerator Aging Effects During Copper

Electrodeposition.” Electrochemical and Solid-State

Letters, 6 (4), C59–C62 (2003).

S.G. Pyo, S. Kim, D. Wheeler, T.P. Moffat, and

D. Josell. “Seam-Free Fabrication of Sub-Micrometer

Copper Interconnects by Iodine-Catalyzed Chemical Vapor

Deposition.” J. Appl. Phys., 93 (2), 1257–1261 (2003).

B.C. Baker, M. Freeman, B. Melnick, D. Wheeler,

D. Josell, and T.P. Moffat. “Superconformal

Electrodeposition of Silver from a KAg(CN)2-KCNKSeCN Electrolyte.” J. Electrochem. Soc., 150 (2),

C61–C66 (2003).

T.P. Moffat, D. Wheeler, C. Witt, and D. Josell.

“Superconformal Electrodeposition Using Derivitized

Substrates.” Electrochemical and Solid-State Letters,

5 (12), C110–C112 (2002).

D. Josell, B. Baker, C. Witt, D. Wheeler, and

T.P. Moffat. “Via Filling by Electrodeposition:

Superconformal Silver and Copper and Conformal Nickel.”

J. Electrochem. Soc., 149 (12), C637–C641 (2002).

Our findings have also been conveyed to the U.S.

microelectronics industry, academia, and other national

laboratories through more than 15 external presentations

in the last year, including an invited presentation at

Intel’s Portland, Oregon facility. Project publications

generated 100+ citations in the past year.

For More Information on this Topic

D. Josell, D. Wheeler, T.P. Moffat (Metallurgy

Division, NIST)

their predictions when applied to more complex conditions

including catalyst accumulation and consumption.

In a development with application far beyond the

microelectronics industry, our recent publication on

the CEAC mechanism of brightening is the first to

quantitatively explain the impact of adsorbed catalyst

on surface stabilization during growth. This work is

possibly the most significant advance in understanding

surface stabilization since the growth of surface

perturbations due to concentration gradients was

first described. It is as significant to creating shiny

electrodeposits of metal on a car bumper as it is to

reducing defect-inducing surface roughness in feature

filling for microelectronics.

Figure 2: The geometry used to define the exact solution for

the superconformal filling of a trench. The metal deposits at the

bottom corners of the trench have met in the middle where a new,

even more rapidly moving, growth front emanates.

Selected Project Publications for FY2003

D. Josell, T.P. Moffat, and D. Wheeler. “An Exact,

Algebraic Solution for the Incubation Period of Superfill,”

J. Electrochem. Soc., (in press).
8

Technical Highlights

High Throughput Data Analysis of Multicomponent

Multiphase Diffusion Data

workshop was the development of a diffusion work

group to address a variety of multicomponent diffusion

questions as well as to promote the development of

multicomponent diffusion mobility data.

Based on the needs identified in 2002, a diffusion

workshop series began at NIST founded on the

following objectives:

■ To improve communication among experts in

multicomponent diffusion measurement, analysis,

and simulation.

■ To establish the most efficient method for extracting

diffusion data (diffusion coefficients, fluxes, marker

location) from multicomponent diffusion couple

experiments.

■ To provide a forum to solve common diffusion

software execution problems.

■ To agree on a common diffusion mobility database

assessment procedure.

■ To establish a general approach to data handling and

diffusion modeling in ordered phases.

■ To develop standard problems and a website for

inter-laboratory comparison of diffusion simulation

methods and data extraction techniques.

Following the above objectives, the first of a series

of workshops on “The High Throughput Analysis of

Multicomponent Multiphase Diffusion Data” was held

at NIST, March 27–28, 2003. The workshop format

was designed to encourage active discussion among

participants and hands-on computer demonstrations.

Presentations on available software for simulating

multicomponent diffusion couples included discussions

of the DICTRA (Diffusion Controlled Transformation)

finite-difference diffusion code and Profiler. The

MultiDiflux software code was presented as a tool

for determining interdiffusion coefficients from

multicomponent data. The development of diffusion

mobility databases was presented.

Discussions also included a review of diffusion

notation, the advantages and disadvantages of various

inverse methods (methods used to determine diffusion

coefficients from experimental composition profiles),

and a review of various experimental techniques.

The group also assessed the limitations of various

commonly used methods, including the limits of the

Darken approach and the Boltzmann–Matano method.

Multicomponent diffusion processes are part of

many complex industrial processes. Reliable data

and analysis are critical to effective understanding

and development of such processes and the

resulting materials. For example, control

of multicomponent diffusion is essential for

optimizing heat treatments, predicting service life

times, and determining optimal material properties.

Developing and modeling these processes requires

efficient methods to use and store massive amounts

of diffusion data as well as improved techniques

for understanding multicomponent diffusion data.

Carelyn E. Campbell and William J. Boettinger

An improved understanding of multicomponent

 multiphase diffusion is motivated by two major

industrial interactions: the DARPA/General Electric

(GE)-led AIM (Advanced Insertion of Materials)

program, which highlighted the need for modeling

multicomponent diffusion in Ni-base superalloys, and

the March 2002 NIST roadmapping workshop on

“Databases for Computational Thermodynamics and

Diffusion Modeling.” As a part of the AIM program,

a diffusion mobility database for Ni-base superalloys

was developed. An essential resource in developing

the diffusion mobility database was the NIST Diffusion

Data Center, which catalogs all of the diffusion work

between 1950 and 1980. The developed diffusion

mobility database was then used in conjunction with

the NIST-developed thermodynamic database for

Ni-base superalloys to simulate various multicomponent

diffusion couples. The diffusion simulations were

compared to experimental results provided by GE.

Figure 1 shows one such comparison for a Ni/Rene88

diffusion couple. The experimental and calculated

composition profiles are in good agreement, but

several questions remain on how to best analyze

the data from multicomponent diffusion couple

experiments. Current diffusion simulation methods

predict the diffusion coefficients as function of

composition and time; however, the ability to extract

comparable experimental diffusion coefficients from

multicomponent diffusion couples is limited.

The second industrial interaction motivating

further diffusion work was the result of interactions

at the March 2002 NIST workshop on “Databases

for Computational Thermodynamics and Diffusion

Modeling.” One of the action items from the 2002
9

Figure 2: Calculated and measured (symbols) Co composition

profiles in the Rene88/IN100 diffusion couple at 1150 oC for

1000 h. At 1150 oC, IN100 is a two phase mixture of γ +γ ́.

The red line is the calculated average Co profile. The blue line

is the Co profile in the γ phase and green is the Co profile in the

γ ́ phase. The light blue region indicates the predicted two-phase

region in the couple after 1000 h at 1150 oC. Experimental data

from GE-CRD.

Technical Highlights

Representatives from industry presented experiences

in using various diffusion software codes as well as

experimental methods. A strong industrial need was

articulated for developing the understanding of diffusion

in amorphous material, specifically in bulk metallic

glasses, and for developing multicomponent diffusion

data and modeling in ordered phases.

In the first diffusion workshop, several action

items were identified, including the development of a

website to post the group’s progress and of various

tools for teaching multicomponent diffusion. A second

diffusion workshop in the fall of 2003 will highlight

an introduction to first principle calculations for

diffusion, experimental issues in obtaining quality

data, and an analysis of multicomponent diffusion in

multiphase materials. The complexity associated

with multicomponent multiphase diffusion is shown

in Figure 2 comparing the experimental and calculated

Co composition profiles for the Rene88/IN100 diffusion

couple. At 1150 oC, IN100 is a two-phase mixture of

γ and γ ́. While the diffusion simulations consider the

two-phase equilibrium during the diffusion simulations,

experimental methods for extracting diffusion

coefficients from multiphase materials are not

well defined.

At both the 2002 NIST Workshop and the 2003

Diffusion Workshop, both industrial and academic

diffusion experts described the value of having the

NIST Diffusion Data Center converted to a searchable

electronic form. The Diffusion Data Center represents

a unique collection of diffusion work up until 1980,

which is cataloged by author, diffusion system, and

selected keywords. The collection contains translations

of published works and difficult-to-obtain government

reports and theses. To preserve this work and to

make it more widely available, the Metallurgy Division

is converting the paper-based catalog to a searchable

electronic format. Once the catalog is converted to

an electronic format, it will be made available on the

NIST website. The work will then focus on converting

the difficult-to-find papers, reports, and theses to an

electronic format, which can be accessible via the

NIST website.

Through the continuing NIST Workshops, action

plans for the Diffusion Working Group, and development

and application of multicomponent diffusion mobility

databases, NIST interaction with academia and industry

will continue to better address critical diffusion issues.

Ultimately, this increased accessibility to diffusion data

will provide material producer and user industries with

a variety of tools to more efficiently use and model

multicomponent diffusion as a vital part of process

modeling.

Figure 1: Calculated (solid lines) and experimental (symbols)

compositon profiles for the Ni/Rene88 diffusion couple at 1150 oC

for 1000 h. Experimental profiles from GE-CRD.

For More Information on this Topic

C.E. Campbell, W.J. Boettinger, U.R. Kattner

(Metallurgy Division, NIST); J.-C. Zhao (GE-CRD)

C.E. Campbell, W.J. Boettinger, and U.R. Kattner.

“The Development of a diffusion mobility database

for Ni-base superalloys.” Acta Mater, 50, 775–792

(2002).

www.ctcms.nist.gov/~cecamp/workshop.html
10

Technical Highlights

Modeling Dynamics, Damping and Defects for Perpendicular

Magnetic Recording Media

In its accelerating march toward ever higher

recording densities, the hard disk drive industry

is moving toward perpendicular recording,

where the magnetization of the written bits is

directed perpendicular to the disk surface. One

of the metrology needs generated by the shift to

perpendicular recording is the characterization

of inhomogeneity in the media. This article

describes our development of models that enable

measurement of inhomogeneity in perpendicular

media by ferromagnetic resonance.

Robert D. McMichael

One of the growing metrology needs of the hard

 drive industry is the ability to characterize the new

generation of perpendicular recording media, where

the information is stored as magnetic bits magnetized

perpendicular to the disk surface. To store these bits,

it is desirable to have media with small, nearly decoupled

grains with strong, uniform anisotropy and easy axes

directed along the disk normal. Typical grain sizes in

the new media are approximately 10 nm.

Characterization of the average properties of

perpendicular media is routinely accomplished by

magnetometry. However, there is a significant need for

information about the inhomogeneity of perpendicular

media, particularly the angular easy axis distribution

and the distribution of anisotropy fields. Inhomogeneity

of the media impacts the bit writing process, analysis

of bit stability, and media noise in the read process.

Information about the dispersion of the

crystallographic axes can be obtained from x-ray

diffraction, but magnetic coupling may force two

crystallographically distinct grains to behave as a single

magnetic grain, so a purely magnetic measurement of

the dispersion angle would be more closely related to

the performance of the media.

For variations in the anisotropy field, the only

estimates currently available are based on TEM

compositional analysis coupled with anisotropy studies

on bulk materials. Here again, a direct, purely magnetic

measurement would give a clearer indication of the

magnetic performance of the media.

The new perpendicular media, with aligned

anisotropy axes, is much better suited to ferromagnetic

resonance measurements than longitudinal media.

Ferromagnetic resonance is a peak in the transverse

susceptibility at a frequency that corresponds to

precession of the magnetization about its equilibrium

orientation. The width of the ferromagnetic resonance

peak, or “line width,” is the combined effect of damping

and inhomogeneity. While there are well-established

models for damping, better models of inhomogeneity

were needed for interpretation of line width data.

Through our modeling the dynamics of

inhomogeneous films, we have laid the theoretical

support needed for interpretation of line width data to

obtain inhomogeneity information on magnetic thin films.

Previously, there were two known models

of ferromagnetic resonance line broadening by

inhomogeneity: the “local resonance” model and

the “two-magnon” model. The local resonance

model assumes that interactions are not important,

and the line width is therefore a direct measure of the

inhomogeneity strength. The “two-magnon” model

includes interactions but, because it is a result of

perturbation theory, is limited to weak inhomogeneity.

The two-magnon linewidth depends quadratically

on the inhomogeneity strength. The models give very

different results, but both models have been successfully

used to describe separate sets of linewidth data.

Figure 1: In the absence of interactions, inhomogeneity leads

to local resonances at a distribution of frequencies, leading to

a broadened resonance line. Interactions cause narrowing of

the envelope peak described by the two-magnon model.

To understand the relationship between the local

resonance and two-magnon models of line width, we

modeled a series of inhomogeneous films with different

grain sizes and different levels of inhomogeneity, and

we computed the eigenmodes of the magnetization
11

Technical Highlights

approximation to the line width, but for larger values of

inhomogeneity, the two magnon results will exceed the

local resonance values and the local resonance results

would be valid.

Figure 2: Line widths as a function of grain size in a Permalloy

film calculated by eigenmode analysis for three random field

strengths Hp. (Open and closed symbols are for two methods of

computing line width from the eigenmode spectrum.) The line

width transitions smoothly from the local resonance model for

large grains (weak interactions) to the two-magnon model when

grains are small. The pink line indicates where interactions and

inhomogeneity are roughly equal.

The full eigenmode analysis takes a significant

amount of computation time, making it a poorly

suited technique for data fitting. However, the results

in Figure 2 suggest a simple first approximation;

for a given combination of microstructure and

inhomogeneity, the lesser of the two-magnon model

and the local resonance model is likely to be valid,

except in the range where they are similar.

Figures 3 and 4 show two-magnon and local

resonance line width calculations for perpendicular

media with thickness 15 nm and grain size 10 nm

with an average anisotropy field of 1.4 T (14 kOe).

In these figures, the top diagram portrays the local

resonance result, the green curve is the two-magnon

model with dipolar interactions only, and the blue

and pink curves are for fractional and full exchange

coupling. For the given inhomogeneity strengths, the

two magnon model results are expected to be a good

Figure 3: Local resonance and two-magnon line widths resulting

from tilting of the easy axis directions in perpendicular recording

media with 10 nm grains. Two magnon results are calculated for

three values of exchange coupling.

Figure 4: Local resonance and two-magnon line widths resulting

from anisotropy variations in perpendicular recording media

with 10 nm grains. Two magnon results are calculated for three

values of exchange coupling.

These results show that the ferromagnetic

resonance line width can be a sensitive probe of

inhomogeneity in perpendicular recording media with

the ability to differentiate damping, c-axis dispersion,

and anisotropy variations. For weak inhomogeneity,

the two-magnon model becomes valid, and the line

width can also provide information about exchange

coupling.

A ferromagnetic resonance apparatus with the

frequency and field ranges necessary to measure

perpendicular media is in the design phase.

For More Information on this Topic

R.D. McMichael, W.F. Egelhoff, Jr. (Metallurgy

Division, NIST)

R.D. McMichael, D.J. Twisselmann, and A. Kunz.

Phys. Rev. Lett., 90, Art. No. 227601 (2003).

motion (Figure 1). We found that the behavior of

the magnetization dynamics depends on the relative

strengths of the interactions and the inhomogeneity.

For a uniform film, the eigenmodes are spin

waves (“magnons” in quantum mechanics), and

inhomogeneities or strong interactions cause mixing

of the spin wave modes in agreement with the two

magnon model. For strong inhomogeneities relative to

interactions, the dynamics were localized on individual

grains in agreement with the local resonance model.

These results are summarized in Figure 2, where

small grain sizes correspond to strong intergranular

interactions, and large grains correspond to weak

interactions. These results unify the local resonance

and two-magnon models.
12

Technical Highlights

Artifacts in Ballistic Magnetoresistance Measurements

Magnetic sensors play a central role in many

important technologies ranging from data storage

to health care to homeland security. A common

need among these technologies is higher

sensitivity and smaller size. Advances in the past

year in the Ballistic Magnetoresistance (BMR)

effect appeared to provide enormous progress in

sensitivity in nanoscale devices. The scientific

press reported it as one of the major discoveries

of the year. Unfortunately, it appears to be wrong.

Experiments at NIST have found that several

simple artifacts can account for the results. NIST

is taking a leading role in designing artifact-free

metrology to provide reliable data to the magnetic

sensor industry.

William F. Egelhoff, Jr.

Magnetic sensors play a central role in many

 important technologies. To name just a few,

computer hard disk drives use magnetic sensors to read

stored data (Figure 1), magnetoencelophalography uses

magnetic sensors to image brain wave activity, and

bio-hazard detectors use magnetic sensors to detect

magnetic beads bio-tagged for anthrax, botulism,

cholera, and other pathogens.

sensor can, at best, exhibit a ≈ 15 % change in

electrical resistance in response to a magnetic field.

Shock waves went through the magnetic-sensor

community in 2003 when a value for the Ballistic

Magnetoresistance effect (BMR) of 100,000 % was

published and a value of 1,000,000 % was reported at

a major scientific conference.

Understanding these results suddenly became a

high priority for the magnetic-sensor community.

For example, Seagate, the world’s leading hard-disk

drive manufacturer, sent Dr. Erik Svedberg, a physicist

in its research labs, to work with us half-time in 2003 to

investigate BMR. Seagate selected to work with NIST

because we already had a strong program in place to

investigate BMR and a network of collaborators that

included those groups reporting the high BMR values.

NIST had initiated the BMR research program prior to

these reports because earlier less-sensational reports

of BMR looked promising but faced a number of

problems. BMR samples had poor reproducibility, poor

stability, and poor reliability. The fabrication techniques

were poorly understood, and there was no theory to

explain the magnitude of the BMR effect. It was felt

that NIST might help with what is often a long, hard

road from a laboratory demonstration of a concept to

a commercially successful device.

 As the NIST program developed over the past

two years, it became clear that other labs were able to

achieve much higher BMR values, some in the 100 % to

700 % range, while NIST results rarely exceeded 10 %.

The trend accelerated in 2002 as these other labs began

reporting results of 3,000 % to 10,000 %. These BMR

values were reported as major discoveries in Science,

Science News, and Physics News.

In late 2002 and early 2003, scientists from these other

labs visited NIST to demonstrate how they achieved these

results. NIST staff analyzed the experiments and found

them to be subject to a variety of artifacts that can mimic

BMR. The small BMR values that NIST had measured

were directly attributable to more careful experimental

design that excluded the artifacts.

The most common artifact is a result of

magnetostriction, in which the length of a magnetic

wire changes length in a magnetic field. Figure 2

illustrates the geometry that produced some of the

sensational effects attributed to BMR. Two Ni wires

are brought together with a gap of ≈ 20 μm. The gap

is bridged by electrodepositing Ni in a way that forms a

nanocontact with one of the Ni wires. This nanocontact

is thought to have dimensions on the order of 10 nm.

When a magnetic field is applied along the axis of one

of the wires, a sharp increase in the electrical resistance

A common need among these technologies is higher

sensitivity and smaller size. With higher sensitivity and

smaller size, more data could be stored on a hard disk,

higher resolution imaging of brain activity would be

possible, and earlier warnings of bio-contamination

could be given.

Currently, the Giant Magnetoresistance (GMR)

effect is used for the best small-scale sensors. A GMR

Figure 1: Computer hard disk drives use a magnetic sensor to

read data.
13

Figure 3: An illustration of how magnetostatic forces cause

magnetic particles to clump together to create conducting paths.

In samples made this way, the no-field case was

the high resistance state, and the with-field case was

the low resistance state. When the particles clumped

together, they created additional current-carrying paths

to lower the electrical resistance. There was no evidence

of anything resembling true BMR in these samples.

A preliminary report of these artifacts was presented

at the March Meeting of the American Physical Society

in 2003. A more comprehensive report of the work will

be presented at the Magnetism & Magnetic Materials

Conference in January 2004.

Experiments are continuing at NIST to put BMR

on a firm scientific foundation. Although a conclusive

answer is not available at this point, the results, so far,

suggest that there may be a small BMR effect but not

one that is large enough to be of great interest to the

magnetic-sensor community. NIST’s work on this

topic is likely to be completed early in FY04.

 “The technical challenges facing the data storage

industry in the next 10 years are so broad and so

deep that the industry cannot do it alone. We need

researchers like you here at NIST to help us.”

Dr. Sining Mao

Senior Manager, Recording Heads

Division, Seagate Technology

For More Information on this Topic

E. Svedberg (Seagate); N. Garcia (CSIC, Madrid);

H. Chopra (SUNY-Buffalo); R. McMichael, T. Moffat,

J. Mallett (Metallurgy Division, NIST); M. Stiles (Electron

and Optical Physics Division, NIST); C. Powell

(Surface and Microanalysis Science Division, NIST)

Technical Highlights

of the nanocontact is observed, as illustrated in the inset

in Figure 2. The results were interpreted as BMR

assuming that the magnetic field was magnetizing the

two sides of the nanocontact in opposite directions and

the resulting magnetic domain wall impeded the flow of

electrons, thereby increasing the measured resistance.

becoming magnetized in the same direction, were

clumping together under the magnetostatic attraction,

as illustrated in Figure 3.

Figure 2: An illustration of the geometry used to generate

sensational apparent BMR values.

A simpler explanation accounts for the result: the

magnetic field also makes the Ni wire shorter. Using the

magnetostriction constant λ for Ni and the length of free

wire, the calculated shortening is 35 nm. This distance

is enough to stretch and severely deform a 10 nm

nanocontact, increasing its electrical resistance. In fact,

in experiments at NIST using electrochemical techniques,

it was possible to break and reform nanocontacts thus

giving what would correspond to infinite BMR.

Further experiments at NIST using alloy wires

whose composition is tailored to have a magnetostriction

constant of zero showed no resistance change in a

magnetic field. These wires were magnetic and should

exhibit BMR if the effect was as claimed, casting

further doubt on the high values reported.

Another approach investigated at NIST involved

replacing the Ni wires with Ni thin films deposited on

wafers. The strength of bonding between the Ni and

the wafer anchored the Ni films and suppressed the

shortening effect. In this geometry, the nanocontact

showed no resistance change, further supporting the

conclusion that the high BMR values were not true BMR.

When informed about the NIST results, one of the

other labs responded with a method to produce the high

BMR values in magnetic nanocontacts electrodeposited

at an unusually large voltage on wafers. NIST examined

the techniques and found that the unusually large

deposition voltage did not produce a solid contact.

Instead, the deposit consisted of loosely assembled

magnetic particles. When a magnetic field was applied,

a compaction of the powder could be observed in a

microscope. The small magnetic particles, upon
14

Technical Highlights

Phase Field Modeling of the Electrochemical Interface

Many important problems in electrochemistry,

such as void formation during plating in vias

and trenches for on-chip metallization or dendrite

formation during recharging of batteries, involve

complex topologies that are not easily treated

by existing models. The phase field modeling

technique has had considerable success studying

similar interfaces, with much of the fundamental

work performed by researchers in the NIST

Metallurgy Division, but the work has almost

exclusively focused on solidification. This project

seeks to bridge the gap between the traditional

electrochemical and phase transformation

modeling communities.

Jon E. Guyer and William J. Boettinger

Electrodeposition is increasingly being applied

 to sub-micrometer features with convoluted

morphologies, such as the “copper damascene” process

of the micro-electronics industry. In this size regime,

factors become important which have been safely

neglected in macroscopic models of electrochemistry.

For example, as length scales shrink, surface curvature

becomes an important consideration; subtle interactions

between surface energy and the selective adsorption

of different species on the electrode surface can no

longer be ignored. Furthermore, traditional models

of electrochemical interfaces, such as that of

Gouy–Chapman–Stern, take the interface between

phases (the transition between electrode and electrolyte)

to be abrupt. Such treatments have difficulty tracking

a real electrochemical interface, which is often

convoluted or can have changing topology, because

the boundary conditions on that interface depend on

its position, which is part of the unknown solution.

The phase field technique is an alternative

approach to modeling phase transformations that

has had considerable success in the past decade in

the modeling of solidification. The method employs a

thermodynamic variable, which is a function of position

and time, to describe whether the material is solid or

liquid. The behavior of this variable is governed by

a partial differential equation that is coupled to the

relevant transport equations for the material. The

interface between the phases is described by smooth

but highly localized changes of this variable. It is not

necessary to explicitly track the interface between

phases or to apply any boundary conditions there.

The method is computationally demanding, but it is

powerful because changes in complex interfaces and

topology occur naturally.

Figure 1: Differential capacitance calculated by our model.

Motivated by the successful phase field models

of solidifying interfaces, we seek to expand NIST’s

“phase field toolkit” into electrochemistry. As a first

step to applying the method to convoluted electrochemical

interfaces, we have developed a 1D model by making a

limited set of assumptions: mass and volume constraints,

Poisson’s equation, ideal solution thermodynamics in the

bulk phases, and a simple description of the competing

energies in the electrode/electrolyte interface.

Equilibrium Interface

The interface between two phases containing free

charges is known to develop a charged “double layer.”

For instance, a layer of excess electrons at the surface

of a metal will mirror a layer of excess cations in the

adjacent electrolyte. Despite the simple assumptions

made in its formulation, our model spontaneously

produces just such a double layer. Even though both

the total charge and the charge in each bulk phase

are zero, we find that there is some non-zero charge

distribution in the interface, just as in physical systems.

Both electrochemical theory and experiments on inert

systems show that the surface charge is directly

coupled to the surface energy and that both depend

on the potential across the interface. In particular,

at the “point of zero charge” (PZC), where the surface

charge is zero, the surface energy has a maximum.

Independent calculations of surface energy and surface

charge using our model exhibit exactly the relationship

expected from traditional theories.

The “differential capacitance” is defined by the

change in surface charge with potential. The value

predicted by classical models of the electrochemical

interface depends on the hyperbolic cosine of potential

near the PZC and becomes a constant for larger potential

differences. The differential capacitance calculated by

our model, however, exhibits complex shapes with multiple

extrema, as seen in Figure 1. This behavior bears a much

stronger resemblance to experimental measurements, such

as in Figure 2, than to previous theories.
15

Technical Highlights

Figure 2: Experimental measurements of differential capacitance

on Ag(100) electrodes in aqueous solutions of NaF. [Reprinted

from J. Electroanal. Chem. 138, G. Valette (1982) 37–54), with

permission from Elsevier.]

Dynamic Interface

Turning now to the examination of electrodeposition

and electrodissolution, when the overpotential (the

deviation from the equilibrium potential difference

across the interface) is not zero, current will flow and

the interface will move. The classical description for

the relationship between current and overpotential is

the empirical Butler–Volmer relation (Figure 3).

behavior that agrees very well with the predictions of

traditional electrochemistry (Figure 3).

At large overpotentials, we find that the most

electroactive cation becomes depleted at the interface

nearly to zero. The concentration gradient can be no

steeper, limiting the rate of cation diffusion to the

interface. In order to carry more current than this

diffusion-limited value, the charge structure of the

interface shifts to allow deposition of less electroactive

species. Figure 4 shows two different times after the

current has been changed from 0.005% to 500% of the

limiting current for the deposition of M, leading to alloy

deposition of M and N.

Figure 3: Current vs. overpotential calculated by our model

(symbols) and predicted by classical Butler–Volmer equation (line).

In contrast, phase field models typically assume that

the rate of change of the phase field is directly proportional

to some driving force. Despite making such a simple

assumption about the kinetic behavior, the rich interplay

among composition, charge, electrostatic potential, and

thermodynamic stability gives rise to current-overpotential

Figure 4: Profiles of the ion concentrations, charge density, and

electrostatic potential at two different times after the current was

changed from 102 A/m2 to 107 A/m2. The gray band indicates the

position of the diffuse phase field interface.

By correctly describing the fundamental physics,

our model spontaneously produces differential

capacitance curves strongly reminiscent of experiments,

nonlinear current-overpotential behavior, and alloy

deposition, all without making ad hoc assumptions.

Future work will focus on further relating the

parameters of the phase field model with those of

traditional electrochemistry, examining larger physical

domains, and to extending the model to two dimensions.

For More Information on this Topic

J. Guyer, W. Boettinger, J. Warren (Metallurgy

Division, NIST); G. McFadden (Mathematical and

Computational Sciences Division, NIST)
16

Technical Highlights

NEMI–NIST–TMS Workshop on Tin Whiskers: Cause and Effect

Figure 1: Three different whisker types from bright Sn coatings;

a) Filament with tip and base shown in insert; b) Odd shaped

eruption with filimenery growths; c) filament growing from an

eruption.

The most commonly used commercial surface

finishes are Tin (Sn) based. Sn whiskers (filament type

whiskers are typically 1 μm diameter and several mm

long) can grow from the Sn plate and cause electrical

shorts and failures. Tin–lead (Pb) alloys have been

used extensively for surface finishing of electronic

components because Pb was found to be effective in

retarding Sn whisker growth and keeping production

costs low. Since Pb-free solder alloys have been

introduced, electronic manufacturers are seeking a

new surface finish technology that will prevent Sn

whisker growth without the use of Pb. Whiskers are

generally believed to grow to relieve residual stress

in electroplated Sn. Figure 2 shows a schematic of

compressive stresses in electrodeposited Sn plating

resulting in the growth of a Sn whisker. Some of the

Figure 2: Schematic of Sn whisker growth from a Sn

electrodeposited plating.

The National Institute of Standards and

Technology (NIST), the National Electronics

Manufacturing Initiative (NEMI), and The Minerals,

Metals & Materials Society (TMS) co-sponsored a

one-day workshop, “Tin Whiskers: Cause and Effect,”

on Sunday, March 2, at the San Diego Convention

Center. The event was held in conjunction with the

2003 TMS Annual Conference and Exhibition.

The agenda consisted of four presentations

during the morning and round table discussions in the

afternoon. The 44 attendees represented a variety of

industrial, academic, and government organizations,

including Analog Devices, Brocade Communications

Systems, Cookson Electronics, Hanyang University,

HP, IBM, Intel, KAIST, Kyocera, Los Alamos National

Lab, Michigan State, Millenium Chemicals, Motorola,

Oak Ridge National Lab, Research in Motion, Sandia

National Laboratory, Shipley TI, Sun Yat-Sen University

(Taiwan), SUNY at Buffalo, Technic, The Aerospace

Corporation, University of Kentucky, and Washington

State University. All of the participants contributed to a

lively afternoon discussion of the papers presented and

current theories.

Stress in Electroplated Sn

Dr. Chen Xu of Cookson Electronics outlined his

work on understanding the whisker growth rate and

carrying out structural and chemical characterizations

of whisker growths. He presented a “whisker index”

— a proposal to characterize whiskers and presented

data on this factor as a function of various types of

Sn plating. He discussed the use of x-ray diffraction

(XRD) for measuring stress in Sn plated films,

showing the changes in stress as a function of time.

His data shows that compressive stress in the film

leads to whisker growth, while tensile stress does not.

key factors that have been found to influence Sn

whisker growth are: deposit thickness, diffusion,

thermal stresses, substrate material, electrolyte type,

plating conditions, temperature, humidity, organic

and inorganic inclusions, grain size and shape, and

interdiffusion barriers. In spite of this wealth of

information, a basic understanding of whisker growth

and its prevention does not currently exist.

This NEMI–NIST–TMS workshop brought together

key researchers to compare in detail research that

has been done in the area of tin whiskers, and

to see if a consensus could be developed on a

basic model defining the conditions for whisker

formation, or, if not, on the work required to

reach such a consensus. The end goal is to

provide direction to the electronics industry in

developing deposition processes that will assure

that long-lifecycle products will not experience

catastrophic failure due to whisker growth.

William J. Boettinger and Maureen Williams

Since the mid 1940s, the phenomenon of metallic

 growths from electrodeposited surface finishes on

electronic components has been observed and studied.

Electrodeposited surface finishes applied to the component

leadframe protect the material from corrosion and

improve solderability of the components prior to board

assembly. These metallic growths are referred to as

whiskers and may form different shapes, as seen in

Figure 1.

a. b. c.
17

Technical Highlights

He presented data to show that a nickel (Ni) under layer

will result in tensile stress in the Sn layer, and he saw

no whisker growth when a Ni layer was deposited

between the Cu and Sn layers.

Spontaneous Growth of Tin Whiskers

Dr. Dong Nyung Lee of the School of Materials

Science and Engineering, Seoul National University

showed results of microstructure characterization

using SEM techniques, including angle of growth, and

pole figures. To release the compressive stress in

the tin film, tin whiskers grow from the grain whose

surface oxide is sheared. The whisker growth is

controlled by the expansion of prismatic dislocation

loop on the slip plane by climb, that is, by means of the

operation of the Bardeen–Herring dislocation source.

Whisker growth continues until the stress is relieved.

Tin-Whisker Microstructural Analysis

Dr. George T. Galyon of the IBM Server Group

provided a critical analysis of the literature outlined in

his Annotated Sn Whisker Bibliography, noting that

there appear to be necessary conditions for whisker

formation (i.e., stress) that are not always sufficient

to explain the overall phenomena. He provided a great

deal of information on the use of the Focused Ion Beam

(FIB) tool in examining whiskers. Very little, and only

recent, work has been reported using this new tool,

and it seems to provide considerable additional insight

into whisker structures. His observations indicate that

whisker growth is the result of a recrystallization of

the tin at the base of the whisker resulting in additional

material pushing the whisker out of the film.

Focused Ion Beam, Transmission Electron

Microscopy, and Synchrotron Radiation

Dr. King N. Tu, of the Department of Materials

Science and Engineering at UCLA, performed studies

on tin whiskers with focused ion beam (FIB) imaging,

cross-section transmission electron microscopy

(XTEM) observation, and synchrotron radiation (SR)

micro-diffraction analysis. Morphology of whiskers

and orientation relationship between a whisker and

grains in the tin plating has been studied by FIB and

XTEM. A large amount of precipitates in the grain

boundaries were observed. The precipitation of Cu6Sn5

intermetallic is believed to maintain the driving force

for spontaneous whisker growth.

Discussion Summary

Discussions established that Sn whiskers are caused

by compressive stress in the Sn plated film, and that

material somehow moves through the grain boundaries

to form a whisker. Whiskers grow from material

deposited at the base of the whisker. The formation

of Cu6Sn5 intermetallics in the Sn grain boundaries

may contribute to the growth of a compressive stress.

The whisker may take advantage of weakness in the

oxide film to erupt.

While no specific mechanism for Sn whisker

growth was established, several questions were posed.

Some of these questions included:

■ Why is recrystallization of Sn necessary for

whisker growth?

■ What is the mechanism by which the Sn is

transported to the whisker base?

Discussions also determined several areas that

require further study to determine the growth

mechanism:

■ The role of Pb in suppressing whisker formation;

the role of a surface oxide layer;

■ The role of texture;

■ The role of impurities; and

■ The role of a diffusion barrier.

An understanding of the details of the nucleation

process is also needed. The most important conclusion

was that further systematic experimental work must be

done to establish the growth mechanism.

Currently at NIST, efforts are focused on analyzing

the average stress relaxation in electrodeposited films

as function of time. These experiments concentrate on

in situ stress measurements during the plating process

and post-plating. Additional experimental work is

planned in collaboration with NEMI members.

“I consider your [NIST Metallurgy Division] group

a key asset to industry in making these decisions on

the soundest possible scientific basis. There is no

comparable body of expertise anywhere in the world

that matches that found in your group.”

Dr. George T. Galyon

(IBM) — Chairman, NEMI

TinWhisker Modeling Committee

For More Information on this Topic

W.J. Boettinger, M. Williams (Metallurgy Division,

NIST); R. Gedney (NEMI); K.-W. Moon (University

of Maryland)
18

Kolsky Bar: Materials Properties at High Strain Rates and

High Heating Rates

Technical Highlights

Materials processed in industry are frequently

placed simultaneously under applied high strain

and heating rates. Understanding, predicting,

and simulating these processes require databases

for materials properties and constitutive equations

verified under similar conditions. NIST has

responded to these industrial needs by developing

a unique testing facility for measuring the needed

data and validating the appropriate material

models under controlled, high rates of straining

and heating.

Richard Fields and Debasis Basak

Machining processes such as turning, milling,

 drilling, broaching, etc., are the most commonly

used methods of producing precision metal parts.

Efficient machining requires a thorough knowledge of

the machine/tool/workpiece interactions. This includes

understanding material behavior under the conditions

of machining. Furthermore, competition has pushed

industry to machine parts as rapidly as possible.

This has led to the development of codes that predict

machining behavior and guide the development of

the most efficient machining practices. These codes

require, as input, mechanical property data that is not

commonly available for most alloys of commercial

interest.

At the tool /workpiece interface, the material

being removed is subject to extremely high forces and

temperatures. The high temperatures arise from the

work dissipated by the large and rapid straining. They

also result from the friction between the tool and the

workpiece material. It has been estimated that the

straining occurs at a rate between 103 s–1 and 106 s–1,

while the heating takes place at rates up to 106 K/s. The

rapid heating is important because most microstructural

features cannot change to their equilibrium structure

in such a short time. Previous attempts at collecting

high temperature data elsewhere have relied on low

rates of heating and thus measured the properties of

inappropriate microstructures. It is the controlled,

high heating rate that makes the current facility unique.

The facility is built around a conventional Kolsky

Bar (sometimes called a Split Hopkinson Pressure Bar)

shown in Figure 1. An air gun fires a striker bar at

speeds up to 50 m/s at the incident bar. On impact, the

striker bar generates a roughly square elastic wave in

the incident bar twice the length of the striker bar and

traveling at nearly 5000 m/s. This wave propagates

down the incident bar to the sample and compresses

the sample between the incident bar and the transmitted

bar. The elastic strain at any time introduced into the

transmitted bar during this process is proportional to

the stress in the sample at that time and the elastic strain

reflected back into the incident bar is proportional to

the strain rate experienced by the sample at that time.

By analyzing the strain signal records, the stress/strain

behavior of the sample material can be determined

under controlled high strain rates.

Figure 1a: Schematic diagram of Kolsky Bar apparatus.

Figure 1b: Photograph of NIST’s Kolsky Bar facility.
19

Technical Highlights

A millisecond-resolution pulse heating facility,

which relies on rapid resistive “Joule heating” of the

specimen by the passage of an electric current pulse

of sub-second duration, is used to heat the specimen.

The connections for the current input can be seen

in Figure 2. Two high-speed pyrometers are used

simultaneously during the test. A spot pyrometer

measures the specimen temperature with microsecondresolution, and an imaging pyrometer records the

temperature distribution in the specimen during the

test. The output from the spot pyrometer is also

used to control the specimen temperature. When the

desired temperature is reached, the electric current

to the specimen is either automatically turned off or

a feedback control program is activated to achieve

isothermal conditions in the specimen, prior to impact.

Figure 2: The current for heating is introduced through copper

blocks and graphite bearings to the incident and transmitted bars,

and then through the sample seen in the middle. The sample

temperature is monitored by the pyrometer being focused on it.

This facility was developed to provide insight and

data for high speed machining of commercial alloys.

To date, it has been used mainly for copper, 303

stainless steel, AISI 1045 steel, and 7075 aluminum

alloy. The results of this research are described under

“High Speed Machining” elsewhere in this annual report.

The data are being provided to industry and other

alloys of commercial interest are being investigated.

More than a dozen papers and talks have been presented

on this topic in the three years that this project has been

underway. Additional papers are being drafted.

Since the facility was developed, other applications

for it have arisen. The World Trade Center Twin

Tower collapses were initiated by the impact of

two commercial airliners. NIST has undertaken the

modeling of these impacts to more fully understand

the events leading up to the failure of the towers.

The models require high strain-rate mechanical

properties. The Kolsky Bar facility is providing the

rate dependence of plastic deformation for the many

types of structural steel in the buildings.

 Another application concerns the behavior

of projectiles such as those used as military tank

penetrators. It has been found that the Kolsky Bar test

is one of the best predictors of thermal localization of

deformation and the self-sharpening behavior desired

in penetrator materials. The Kolsky Bar facility is

providing a project in the Metallurgy Division that is

investigating new penetrator materials with a rapid

assessment of whether their materials or processing

routes are improving penetration behavior.

Lastly, considering the significant number of

conventional Kolsky bars in use in the U.S., an effort

has been initiated to compare the consistency of

measurements made with these instruments. To date,

NIST has compared its results on 1045 steel and

copper with similar results at Aberdeen Proving

Grounds and Los Alamos National Laboratory.

Such intercomparisons will help improve and

maintain consistency of dynamic materials

properties measurements.

New applications for this unique facility are being

pursued in the areas of dynamic fracture and crack

arrest of high strength pipeline steels, bullets and body

armor for the Office of Law Enforcement Standards,

and additional issues in manufacturing. Since certain

types of explosions involve intense, rapid, radiative

heating followed by a shock wave, it is felt that the

new Kolsky Bar facility may play an important role

in research relating to homeland security.

For More Information on this Topic

Richard Fields, L. Levine, R. deWit (Metallurgy

Division, NIST); R. Rhorer, R. Polvani, K. Jurrens,

R. Ivester, H. Soons, M. Kennedy, B. Dutterer,

(Manufacturing Metrology Division, NIST); T. Burns

(Mathematical and Computational Sciences Division,

NIST); H. Yoon (Optical Technology Division, NIST);

Debasis Basak (University of Tennessee); M. Davies

(University of North Carolina, Charlotte)
20

Program Overview

Advanced Manufacturing Methods

The industrial competitiveness of U.S. manufacturers

depends on their ability to reduce the time from product

concept to market while decreasing product cost. This

is as true for well-established “commodity” industries,

such as automotive and aerospace, as it is for rapidly

growing or emerging industries, such as biotechnology

and nanotechnology. Manufacturing is a critical step

in realizing such reductions in product cycle time:

for many industries and products, the rapid, low-cost

development of manufacturing processes is needed

to create new materials with complex product shapes

and higher performance at the same or lower cost as

the competing, older materials and methods.

To realize such improvements in manufacturing,

MSEL is working to develop robust measurement

methods, standards, and materials and process data

that will help in the design, monitoring, and control

of manufacturing processes. An increasingly

important step in manufacturing is process modeling.

Development of optimized manufacturing processes,

such as stamping of complex auto panels or machining

of large aircraft components, is time consuming and

labor intensive. In many cases, the resulting processes

are far from optimal because materials variability, caused,

for example, by residual stresses or strain localization

during processing, leads to lower yields. Our approach

is to develop and combine higher precision, spatially

localized measurement methods with realistic,

physics-based modeling of manufacturing processes

and materials process data to create more useful

process modeling tools.

Depending on the stage of the research, our

research is often conducted in close collaboration

with industrial consortia and standards organizations.

This close working relationship developed through

these organizations not only ensures the relevance of

our research, but also promotes rapid transfer of our

research to industry for implementation.

The performance of metallic components in products

is strongly dependent on processing conditions that

determine microstructural features, such as grain size

and shape, texture, the distribution of crystalline phases,

macro- and microsegregation, and defect structure

and distribution. NIST expertise is applied from a

wide range of disciplines, including thermodynamics,

electrochemistry, fluid mechanics, diffusion, x-ray,

and thermal analysis, to develop measurement methods

and understand the influence of processing steps

for industries as diverse as automotive, aerospace,

microelectronics, and defense. Two major MSEL efforts

in Polymer Processing and Forming of Lightweight

Metals are centered on unique measurement facilities.

Rapidly growing and emerging industries such as

biotechnology and nanotechnology are also dependent

upon the development of new advanced manufacturing

methods that can produce metallic components with

the desired characteristics and performance. Related

projects with significant manufacturing processes

components can be found in the MSEL Programs

on Nanocharacterization, Materials for Micro- and

Opto-Electronics, and the Interface of Materials

with Biology.

Forming of Lightweight Metals

Automobile manufacturing is a materials

intensive industry that involves about 10 % of the U.S.

workforce. In spite of the use of the most advanced,

cost-effective technologies, this globally competitive

industry still has productivity issues related to

measurement science and data. Chief among these

is the difficulty encountered in die manufacture for

sheet metal forming. In the ATP-sponsored workshop

(The Road Ahead, June 20–22, 2000), the main

obstacle to reducing the time between accepting a new

design and actual production of parts was identified

as producing working die sets. To benefit from the

weight saving of high strength steel and aluminum

alloys, a whole new level of formability measurement

methods and data is needed, together with a better

understanding of the physics behind metal deformation.

MSEL is working to fill this need.

Polymers Processing

Polymers have become ubiquitous in the modern

economy because of their ease of processing, high

functionality, and low cost. However, these materials

can exhibit complex and sometimes catastrophic

responses to the forces imposed during manufacturing,

thereby limiting processing rates and the ability to

predict ultimate properties. The focus of our polymer

research is on microscale processing, modeling of

processing instabilities, and on-line process monitoring

of polymers. Our unique extrusion visualization facility

combines in-line microscopy and light scattering for the

study of polymer blends, extrusion instabilities, and the

action of additives. Current applications focus on

understanding and controlling the “sharkskin instability”

in polymer extrusion and observation of the dielectric

properties of polymer nanocomposites. Fluorescence

techniques are developed to measure critical process

parameters such as polymer temperature and orientation

that were hitherto inaccessible. These measurements

are carried out in close collaboration with interested

industrial partners.

Contact: Carol A. Handwerker
21

Advanced Manufacturing Methods

Anelasticity and Springback Predictability

Increased computing power and finite element

modeling methods have brought the prediction

of springback and springback-compensated die

design within reach of industry. In developing

this technology, industry has identified areas

where better measurement methods and data

are required, and in some cases, where scientific

understanding of materials behavior is incomplete.

One such case is the influence of plastic deformation

on mechanisms of anelastic recovery and

springback. The objective of this project is to

develop fundamental understanding, test methods,

and data required to predict this phenomenon.

Richard Ricker

AU.S. Council for Automotive Research (USCAR)

 Consortium on Springback Prediction has

developed finite element springback prediction models

to the point where they are considering using these

models to guide the design of stamping dies. However,

current models have consistently under-predicted

springback leading to the inclusion into the models of

arbitrary correction factors determined from stamping

trials. The systematic and alloy dependent nature of

these errors indicate that the materials property data

used in making these predictions may be responsible.

Preliminary experiments in FY 2002 indicated that this

issue warranted further investigation by NIST using a

dynamic thermal-mechanical analyzer (DMA) capable

of partitioning springback into elastic and anelastic

(time independent and dependent) mechanisms.

For FY 2003, the main objective was to evaluate

the hypothesis that plastic deformation alters the

instantaneous elastic modulus (ME) of Al alloys. Earlier

work using tensile deformation indicated a modulus

reduction, but the plastic strain range that could be

studied was limited and the reductions were small

compared to those produced by texture changes

(<<19 %). Through DMA experiments on Al sheet

deformed in biaxial tension, ME was shown to be

lower by 12 % to 18 % by deformation. Although

changing texture can lead to large changes in properties,

with ME varying as much as 19 % with direction in

Al single crystals, texture measurements at the NIST

Center for Neutron Research (Figure 2) combined

with elastic moduli estimated for the measured

orientation distribution functions (Figure 3) demonstrate

unequivocally that plastic deformation lowers (ME)

beyond that which can be produced by texture changes.

These results were presented at quarterly meetings

of the USCAR Springback Predictability consortia.

Issues to be addressed in the future include prediction

methods for elastic and anelastic modulii, development

of standard practices for developing data, and a better

understanding of underlying causes of the effect.

While Figure 1 indicates that a simple empirical model

can be used to incorporate these effects in springback

FEA codes, the fundamental physics underlying this effect

and its dependence on composition is not yet known.

Contributors and Collaborators

S.W. Banovic, D. Dayan, L. Ma, A. Munitz,

D.J. Pitchure (Metallurgy Division); H. Prask, V. Luzin

(NIST Center for Neutron Research); E. Chu (Alcoa);

USCAR Springback Consortia (Alcoa, DaimlerChrysler,

Ford, GM, LSTC, U.S. Steel)

Figure 1: The measured elastic modulus of two aluminum alloys

as a function of equivalent strain.

Figure 2: Measured (200) pole figures for AA5052 before and

after balanced biaxial deformation.

Figure 3: Predicted elastic moduli for measured pole figures

and Al single crystal elastic constants.
22

Advanced Manufacturing Methods

Microstructural Origins of Surface Roughening and

Strain Localizations

Existing data, measurement methods, and the

basic understanding of metallurgical factors that

influence friction, tearing, and surface finish

during sheet metal fabrication are insufficient to

meet the finite element modeling requirements of

industry. This project approaches the resultant

need by exploring the microstructural origins

of the distribution of slip, surface roughening,

and strain localization during plastic straining.

Influence of initial material characteristics on the

formability of Al- and Fe-based sheet metals as

a function of biaxial deformation is the primary

focus of the investigations.

Stephen W. Banovic and Mark R. Stoudt

Replacement of conventional steel sheets by

 aluminum alloys and high-strength low-alloy

steels for various automobile closures is an effective

means of reducing vehicle weight in an effort to

increase fuel efficiency. However, widespread

application of these materials by the automotive

industry is limited primarily due to formability issues

and material database /constitutive law deficiencies

encountered in finite element modeling. Therefore,

this project examines the underlying structure–property

relationships associated with formability in an attempt

to further the numerical simulations that predict

deformation behavior of materials.

The main focus of this past year was to enhance

the methodology of surface roughness measurements

and to develop new analysis techniques to extract

characteristics in the roughness data. By utilizing the

appropriate analysis techniques, surface roughness

measurements can be a tool to identify which

deformation mechanisms were active, assess the

roughening that is characteristic of that mechanism,

and provide information regarding the range of activity

of that mechanism as a function of metallurgical

condition. Preliminary results from an ongoing

study of the influence of strain path on surface

roughness have recently shown that the resolution

of the instrument is crucial to obtaining statistically

significant results and understanding their meaning.

Figure 1 shows the topography obtained with

scanning laser confocal microscopy (SLCM) of a

1xxx-series aluminum sheet deformed in balanced

biaxial tension. With traditional contact profilometry,

the basic assessment of the roughness can be obtained,

however the data do not distinguish between the baseline

roughness and that which is characteristic of the plastic

deformation. This is an inherent limitation caused by

the profilometer stylus acting as a low-pass filter that

cuts off the short wavelength component of the roughness

and limits resolution of small surface features. In

addition, specific microstructural features cannot be

targeted by this method. Conversely, analysis with

SLCM yields a broader spectrum of information about

the roughness character. An example can be found in

the inset of the figure, which displays the corresponding

roughness profile from the 90 μm line profile shown.

The analysis provides considerable information about

the height and distribution of the individual slip steps

regardless of the surrounding features of the milled

surface. With this additional information, a more

accurate model of the roughening process in this

material can be developed. These results are of

significant interest to automotive manufacturers who

have requested that we develop a NIST Recommended

Practice Guide for Roughness Measurements.

Future work will focus on surface roughness

development and crystallographic texture evolution

of Al- and Fe-based materials deformed via multi-pass

strain paths to more accurately simulate actual

stamping operations.

Contributors and Collaborators

T. Foecke, R.E. Ricker, D. Dayan (Metallurgy

Division, NIST); M.D. Vaudin (Ceramics Division,

NIST), T. Gnäupel-Herold, V. Luzin (NIST Center for

Neutron Research); Y. Shim (University of Georgia)

Figure 1: Surface topography of a 1xxx-series aluminum alloy,

deformed to a true strain of 0.1, obtained using scanning laser

confocal microscopy.
23

Advanced Manufacturing Methods

Plasticity, Fabrication Processes, and Performance

Prediction of large strain plasticity under complex

load histories, such as those applied during

industrially relevant processes, is limited due

to our limited understanding of the role played

by microstructure. Advances in theoretical and

modeling capabilities that include microstructure,

guided by experimental measurements and

validation, are needed to shed new light on this

problem. For example, Object Oriented Finite

Element (OOF) programs are limited by their

inability to deal with plasticity. Remedying this is

one of the principal challenges of this project.

Richard Fields

Diffraction provides a powerful means of very

 accurately measuring both microstructure

and mechanical behavior in a way that provides

insight simultaneously into both, and offers particular

opportunities for understanding plasticity. This project

is implementing one or more plasticity models in OOF

and devising critical experimental and computational

benchmarks to validate OOF using the NCNR’s neutron

diffractometer to measure residual stress, texture,

and elastic properties. Conventional x-ray sources

are also being used where stress states measured at

or near surfaces are important for understanding the

behavior of materials or to compare with predictions.

Synchrotron x-rays are used to deal with subsurface

residual stresses in the thin, highly textured samples

that result from simulated forming operations.

Specifically, the following tasks are underway:

■ Experimentally validate calculations of the important

role played by residual stresses on high-precision

machining and forming operations (includes

collaborative contributions from MEL, ALCOA,

and Boeing Corporation);

■ Provide technical assistance and validation testing to

CTCMS staff engaged in adding 3D plasticity to OOF;

■ Develop the ability to characterize near-surface

residual stresses; and

■ Further develop neutron and synchrotron radiation

sources to provide high-resolution data needed to

relate microstructure, residual stresses, and their

effect on springback, etc.

Once plasticity has been implemented in OOF,

additional verification tests will be carried out against

analytical and numerical models. Validation tests will

be carried out against benchmark experiments run at

the NCNR and in the Metallurgy Division. An effort to

include basic 3-D aspects to OOF based on stereology

may be included in this part of the research.

Accomplishments

■ Validation of Distortion Prediction Method:

In 2002, we validated residual stress measurement

and prediction methods of industry. In 2003,

we generated shapes with measured distortion

machined from self-stressed bodies to compare

with industry-predicted behavior.

■ Test of OOF: Textured polycrystalline samples were

tested for elastic modulus dependence on texture.

The results were compared with predictions using

EBSD (Electron Backscatter Diffraction) and OOF

(Figure 1). The predictions, while promising, require

further study to understand differences between

measurements, calculations, and predictions.

■ Residual stresses in standard forming cups were

measured and provided to the Forming Program

project on Formability Standards. In addition, analyses

were done to understand the origin of these stresses.

This project has targeted a need expressed by

numerous companies to extend OOF calculations into

the plastic range. It is also responsive to the metal

forming research needs of the auto industry, as well

as Boeing, ALCOA, and steel manufacturers with

whom NIST currently collaborates. Improvements in

predicting large plastic strain behavior under complex

loading conditions will have significant benefits on

product differentiation, time-to-market, and the cost

of forming dies for U.S. products.

Contributors and Collaborators

L. Levine, R. deWit (Metallurgy Division, NIST);

H. Prask, T. Gnäupel-Herold, V. Luzin (NIST Center

for Neutron Research); R. Polvani (Manufacturing

Metrology Division, NIST); D. Bowden (Boeing);

E. Chu (ALCOA); R. Reno (University of Maryland)

Figure 1: Comparison of measured elastic modulus dependence

on texture with predictions using EBSD and OOF model.
24

Advanced Manufacturing Methods

Standard Tests and Data for Sheet Metal Formability

In order to meet the USCAR /Freedom Car goals

for fuel efficiency, the U.S. automotive industry

is moving to lighter, high-strength materials for

auto bodies. A NIST survey of industry has found

that providing designers with accurate material

properties, and a way to incorporate them into

finite element models of sheet metal forming dies,

is a critical need for the U.S. auto industry. This

project seeks to develop new standard tests and

metrology to accurately determine sheet metal

mechanical response under forming conditions.

Tim Foecke

I

n order for the U.S. automotive industry to be able

 to transition to new materials for formed sheet metal

parts, they must be able to mechanically characterize

the starting materials under forming conditions,

and input this information into die design models.

In response to this need, we are developing sheet metal

formability tests, along with associated metrology,

that can be standardized and used by industry.

Springback is the elastic shape change to a part

associated with the residual stresses that develop

during the stamping process. This shape change

complicates assembly and accurate fit-up, and the

automotive industry wants to either avoid it or at

least be able to predict its magnitude and design dies

to account for it. The proposed test for springback

consists of splitting open a ring cut from the sidewall

of a deep drawn cup.

In 2003, we have concentrated on establishing the

robustness of the springback cup test to experimental

errors, in preparation for submission of the test to

ASTM, and measurement of residual stresses within

the cups using x-rays and neutrons. Errors in ring

location and geometry, as well as blank misplacement,

produced changes in the springback opening. It was

found that displacing the ring location vertically along

the sidewall of the cup produced the greatest effect

(10 % per mm of error), and that blank misalignment

greatly increased data scatter. The former is related

to the effect of changing thickness on the ring’s area

moment of inertia and the latter on thickness variations

around the ring. Standardization is planned via a

round-robin analysis coordinated through ASTM.

New this year is the installation of an x-ray stress

measuring system on the sheet metal formability

station (Figure 1) that will lead to a standard test

for measuring multiaxial flow surfaces. This new

instrumentation allows for direct, in situ measurement

of the stress in a given direction while the sample is

under biaxial load. Using a series of deformation steps

and the sample geometries previously developed to

produce multiaxial strain states, one can, for the first

time, directly measure the multiaxial flow surface of

a sheet metal. The facility is able to test both steel

and aluminum samples but can be upgraded to test

any metal.

Three other tasks using these new experimental

capabilities have been initiated. The first is a

collaboration with GM and ALCOA on developing

stress-based forming limits, where the multiaxial

stress-strain surfaces measured will be used to verify

path independence of this formalism. The second

involves studying the percentage of retained austenite

transformation in TRIP automotive sheet steel as a

function of strain state and level, in collaboration with

U.S. Steel. Finally, stress-based hole expansion forming

limits will be examined by looking at the stress-strain

response of the material immediately adjacent to a hole

expanding in multiaxial tension. This last project is in

collaboration with GM.

Contributors and Collaborators

T. Gnäupel-Herold (NIST Center for Neutron

Research); M. Shi (USS); E. Chu (ALCOA);

C. Xia (Ford); T. Stoughton, M. Wenner, C.T. Wang

(GM); A. Andersson (Volvo); E. Schedin (Avestapolarit)

Figure 1: Equipment for measuring stress simultaneously

with forming operation.
25

Advanced Manufacturing Methods

Underlying Processes of Plastic Deformation in Metal Alloys

A substantial increase in the use of aluminum

alloys and high-strength steels in automobiles

would greatly increase fuel efficiency. The

primary reason why this has not yet occurred is

a lack of accurate deformation models for use

in designing the stamping dies. This project is

developing a physically based model of plastic

deformation using a combination of statistical

physics approaches and advanced measurement

techniques.

Lyle E. Levine

P lastic deformation of metals (as in cold rolling,

stamping, drawing, and metal fatigue) is a topic

of great importance to industries worldwide, and

improvements in the basic technology would have a

significant effect on our economy. The design of new

metal products is often accomplished by computer

simulation of the production process using empirically

derived constitutive equations. Unfortunately, existing

constitutive equations cannot accurately predict the

material behavior, and many tryout and redesign steps

are required. Another related difficulty is in the design

of new alloys with improved formability characteristics.

Currently, alloy design is done empirically with little

understanding of how the various constituents affect

the mechanical properties.

To address both of these issues, this project is

focused on developing constitutive laws based upon

the underlying physical processes that produce the

observed mechanical behaviors in metal alloys. Such

constitutive laws are inherently multi-scale since they

must describe phenomena on length scales ranging

from the atomistic all the way to the macroscopic

stress-strain behavior of bulk material.

Since the underlying processes are extremely

complex, we have concentrated almost all of our

theory, modeling, and experimental efforts over the

past several years on single-crystal pure Al as a model

system. This work is reaching completion with the

development of the segment length distribution (SLD)

model, which describes how macroscopic deformation

arises from the statistical behavior of large numbers

of dislocations.

The project was in a state of transition this year.

With work on the SLD model nearing completion, the

focus is shifting into several new directions. The first

is a multi-institutional effort to obtain experimental

measurements to validate and provide inputs into the

new NIST models. Our partners include researchers at

Washington State University who are funded by DOE

for four years to conduct chemi- and photo-emission

studies of Al alloys deformed in situ. These experiments

will measure the time-intensity behavior of individual

slip events that are predicted by NIST researchers. The

dislocation substructures of the samples will be studied

by researchers at Los Alamos National Laboratory.

NIST researchers are making the theoretical predictions

and designing an ultra-high-vacuum tensile stage. NIST

will also grow all of the single-crystal alloy samples.

A second new direction is incorporation of

atomistic-level processes into the SLD model, allowing

chemical effects to be addressed. A collaboration with

NIST’s Chemical Science and Technology Laboratory

is beginning, and a jointly funded postdoc joined us in

August 2003. This work should allow quantitative

predictions to be made of the effects of different

alloying elements on mechanical behavior during plastic

deformation.

The third new direction in progress is a

preliminary look at whether the SLD model can be

extended to bcc metals. This task involves growing

shaped, single-crystal samples of a bcc MgLi alloy and

deforming them in tension. The resulting dislocation

structures will be studied using TEM, and the surface

slip structures will be imaged using a variety of

microscopic techniques.

Finally, we are working with researchers at

Oregon State University to answer long-standing

questions about the existence and magnitude of longrange residual stresses that occur during deformation.

X-ray diffraction techniques are often used to measure

these stresses, but interpretation of the results is

subject to question. We are addressing this lack

through both synchrotron X-ray experiments and

computer simulations.

NIST researchers also co-organized two large

international symposia including one on multiscale

modeling at the MRS spring meeting in San Francisco

(April 21–25) and one on dislocations at Plasticity 2003

in Quebec City, July 7–11.

Contributors and Collaborators

D. Pitchure, M.R. Stoudt, R.M. Thomson (Metallurgy

Division, NIST); K. Luedek (SURF student); A. Chaka

(Physical and Chemical Properties Division, NIST);

D. Shechtman (University of Maryland); T. Dickinson,

S. Langford, M. Cai (Washington State University);

M. Delos-Reyes, M. Kassner (Oregon State University);

R. McCabe (LANL); G. Levi (Technion, ISRAEL)
26

Atomization Processing — Recommended Practices

Powder Metallurgy (PM) is used to produce a

large number of metallic materials that benefit

from the enhanced homogeneity and reduced

machining afforded by this process. Higher

performance PM products and process economics

impose increasing demands on the control of

powder size during the gas atomization process.

The NIST Metallurgy Division atomization facility

has been a test-bed for providing the PM industry

with material property data and processing

procedures for improving yield of desirable

powder size distributions. This information is

being compiled into a comprehensive “Gas

Atomization Recommended Practice Guide.”

Stephen D. Ridder and Steven Mates

Gas Atomization is the primary source of

 material for many advanced Powder Metal (PM)

processing procedures such as Powder Injection

Molding (PIM), Hot Isostatic Press (HIP) consolidation,

and Thermal Spray (TS) coatings. These processes

are used to produce surgical tools and appliances,

aircraft and power turbine engine parts, severe service

parts for the petrochemical industry, and increasing

numbers of critical automotive components. Powder

size, because of its affects on microstructure, powder

handling, and consolidation, controls the resulting

PM material properties.

The cost to produce these optimum powder size

distributions can become prohibitively expensive when

using traditional gas atomization techniques that require

screening of the powder product for usable powder and

recycling the waste. Research collaborators representing

the major gas atomization companies and national

laboratories have participated in various projects aimed

at sensor development, alloy chemistry, particle size

control, and powder characterization. Current contents

in a NIST Special Publication, “Gas Atomization

Recommended Practice Guide,” include:

■ Sensors and control techniques to optimize the

Gas-to-Metal mass flow-rate Ratio (GMR);

■ Gas jet geometry designs that reduce adverse

shock wave generation; and

■ Advanced process control software that incorporates

atomization plume video frames and “knowledge

base” heuristics.

Additional research topics of interest to the PM

industry will be published in supplements to the NIST

Special Publication. A new topic under investigation

is the effect of “swirl,” a tangential velocity imposed

on the atomization gas flow, on atomizing behavior.

Swirl is sometimes imparted to the gas flow in an

attempt to enhance melt breakup in the near region.

However, swirl is known to speed turbulent diffusion,

a process that leads to rapid attenuation of the gas

velocity downstream of the near region. As a result,

secondary atomization is potentially hindered, resulting

in wider particle size distributions or unwanted coarse

particles. We are currently quantifying the effect of

swirl strength on the aerodynamic behavior (Figure 1)

and atomization performance of generic nozzles meant

to simulate current industrial practice.

In addition, a small-scale gas atomizer has been

assembled to atomize small heats (less than 500 g) for the

purposes of studying both bulk metallic glass formation

and particle size/processing parameter relationships.

The ultimate goal of the latter is to deduce more accurate

particle size prediction equations that can be used to boost

efficiency in industrial powder production operations.

Ongoing collaboration with industrial partners

continues to be an important component of liquid metal

atomization research at NIST and technology transfer

of the results of our previous atomization research.

“The research history of NIST, and background of

the scientists involved with our project at NIST, give the

company confidence that we will reach a best-possible

solution within the bounds which are dictated by the

real, practical limitations of our plant.”

John Askeland

Operations Manager, Ampal Corp.

Contributors and Collaborators

F.S. Biancaniello, P.A. Boyer, R.D. Jiggetts,

D. Wickner (Metallurgy Division, NIST);

John Askeland (AMPAL)

Figure 1: Effect of swirl strength on axial gas velocity

distribution produced by an annular atomizer.

Advanced Manufacturing Methods
27

High Speed Machining

The U.S. spends $200 billion annually on

machining of metal parts. The rapid development

of high-speed machines and tooling makes

traditional knowledge-based approaches to

improved efficiency ineffective: a recent survey

found that industry chooses the correct machining

tool less than half of the time. Modeling has been

promoted by industry as a method to realize improved

efficiency. Through this project, NIST will develop

measurement capabilities and deliver materials

data for use in machining simulation software.

Richard J. Fields and Carelyn E. Campbell

Machining of metal parts to required dimensional

 tolerances is an essential component of the

manufacturing process. Efficient processes can greatly

reduce the price of parts and enhance the competitive

position of the manufacturer. Industry now requires

that traditional, experience-based approaches to finding

optimal process parameters, such as feed rate, cutting

rate, tool material, tool shape, etc., be replaced by

modeling and simulation. Commercial simulation

codes exist to assist this optimization. However, the

codes require a realistic materials property database and

validation. NIST will publish data for use in these codes

by: (1) measurement of mechanical property data at

high strain and heating rates; and (2) characterization

and modeling of the deformation modes and

microstructure changes that occur during machining.

Residual stresses, responsible for part distortion after

machining, are being measured at the Center for

Neutron Research. Thermal imaging of machining is

being performed by the Optical Technology Division.

The second task focuses on microstructure changes

during machining. Initial work examined severely heated

and deformed chip material. Transmission electron

microscopy reveals that only slight coarsening of the

precipitate structure occurs, but significant changes

in grain size are evident. Figure 2 shows that shear

bands seen in optical micrographs contain dynamically

recrystallized grains. Similar characterization is being

performed on the work piece. A microstructural model

based on the microstructural characterization and the

expected temperature and strain rate histories during

machining is being developed.

Contributors and Collaborators

D. Basak, W.J. Boettinger, L. Bendersky,

L.E. Levine (Metallurgy Division, NIST); R. Rhorer,

R. Polvani, K. Jurrens, M. Kennedy, R. Ivester, and

H. Soons (Manufacturing Metrology Division, NIST);

B. Dutterer (Fabrication Technology Division, NIST);

T. Burns (Mathematical and Computational Sciences

Division, NIST); H. Yoon (Optical Technology Division,

NIST); M. Davies (North Carolina State University)

Figure 1: Stress/strain behavior of AISI 1045 steel tested at

various temperatures and high strain rates.

Figure 2: Optical (left) and TEM (right) images of 7075 chips

with localized deformation and recrystallization.

Advanced Manufacturing Methods

The first task has developed a unique testing

facility for measuring mechanical behavior of alloys

under conditions close to those occurring in machining

operations; i.e., at strain rates up to 104 s–1 with

concurrent heating to test temperatures at rates up

to 5 x 105 K/s. Complete stress/strain data can be

recorded with better than microsecond resolution.

The temperature is known with similar temporal

resolution. This facility has been used this year to

develop a database and test various constitutive laws

for AISI 1045 steel, an important alloy for machining.

In Figure 1, the behavior of this steel at various high

strain rates and temperatures is shown. Samples of

7075-T61 aluminum alloy are also being prepared for

mechanical testing with this instrument.
28

Phase field modeling techniques developed in

the last decade have added considerably to the

understanding of solidification microstructures

such as dendrites, grains, and eutectics. NIST

Metallurgists have taken, and continue to take,

a leading role in these developments. This project

seeks to extend NIST’s “phase field toolkit” to

encompass electrochemical processes.

Jonathan E. Guyer

As manufacturing industries increase their reliance

 on microstructure-dependent properties, control

over microstructure becomes critical to product

performance. Process modeling has become an

important input to design of many manufacturing

processes. As an example, the microelectronics

industry uses electrochemistry to form the intricate

array of interconnects in advanced microprocessors.

Traditional electrochemical models make a number of

assumptions that break down at these length scales,

particularly when voids can form or disappear.

Many of the same morphological features are found

in both solidification and in electrodeposition. The phase

field technique has had considerable success in modeling

these features during solidification. (For a brief description

of the method and initial application to electrochemical

interfaces, see Technical Highlights.) We are able to

model both the equilibrium and kinetic behavior seen in

electrochemical experiments and in earlier models while

making a minimal set of assumptions. Despite these

successes, the electrochemical problem is a particularly

challenging application of the phase field method, and

there are a number of barriers to overcome before we

can model macroscopic 2D systems.

A trivial phase field model of a solid–liquid interface

can be constructed with just one variable: the phase

field itself. To apply the method to an electrochemical

interface, we must also consider the electrostatic

potential and a minimum of three independent charged

species: electrons, cations, and anions. Instead of one

governing equation, the minimal electrochemical model

is thus governed by five, each of which is coupled to all

of the others. The simplest electrochemical phase field

model is intrinsically more difficult to solve than even

some fairly complicated solidification phase field models.

Quantitative results are obtained from a mathematical

model by rendering the equations on a discrete mesh of

points or elements. Typical phase field models require five

to ten mesh points to adequately resolve the interface

between phases. Because of the short range of electrostatic

Phase Field Modeling of the Electrochemical Interface

interactions, we need an order of magnitude more

mesh points to resolve the charge distribution in the

electrochemical interface, as illustrated in Figure 1.

An adaptive meshing technique was also applied.

In this approach, mesh points are concentrated at the

interface as needed, resulting in considerably faster

computations from a good initial guess (calculations

take a few minutes instead of a few days). Unfortunately,

the algorithm does not converge at all from a poor guess,

whereas the simpler uniform mesh code can eventually

obtain a solution from almost any initial condition.

The two approaches were applied in concert to obtain

the results described in our earlier Technical Highlight.

In the algorithm we have applied so far, chosen

for its simplicity of implementation, computation time

is proportional to the square of the number of points.

Considering that our present 1D calculations of a

1 nm section through the interface can take upwards

of three days on a fast computer, a naïve approach

to 2D calculations of the same domain could take

10,000 years. Macroscopic features such as dendrites

would take many orders of magnitude longer to

model. Faster computers can mitigate some of this

computation time, but practical solutions will require

more efficient numerical algorithms.

In the next year, we will focus on more sophisticated

algorithms that minimize the cost of adding mesh points.

In parallel, we will reduce the total number of mesh points

through adaptive meshing techniques. Although the

particular adaptive technique used in our 1D solutions

cannot be scaled to 2D, the general approach should

significantly reduce computation times.

Contributors and Collaborators

W. Boettinger, J. Warren (Metallurgy Division,

NIST); G. McFadden (Mathematical and Computational

Sciences Division, NIST)

Figure 1: Calculated charge distribution in the electrochemical

“double layer” for different interface potentials. The tick marks

above illustrate the uniform and adaptive computational meshes

required to obtain accurate numeric solutions. The gray band

shows the location of the diffuse phase field interface.

Advanced Manufacturing Methods
29

Processing of Amorphous Metals

Recently developed metal alloy chemistries

that solidify amorphously in cross sections

approaching several centimeters are the focus

of increasing interest in the production of large,

meter-scale components by powder consolidation

for use in a variety of challenging military,

aerospace, and industrial applications.

The Metallurgy Division is combining rapid

solidification processing and instrumented

powder consolidation to study the production

and densification of several classes of these

new amorphous alloys.

Frank Biancaniello and Rodney Jiggetts

Recently developed bulk amorphous metal (BAM)

 alloys have been shown to exhibit plastic behavior

in the absence of dislocations, resulting in materials

with high-yield strength, high modulus, and high

hardness. These include low density aluminum-based

amorphous materials identified by Boeing that may

replace titanium in jet engines and high density

hafnium-based alloys being developed by the Army.

The Army’s interest in high-density BAM alloys is a

result of their need for a new armor piercing projectile

material to replace the current Depleted Uranium (DU)

technology. Although DU is a very effective projectile

material, the resulting radioactive and otherwise toxic

debris is difficult to remove from the environment. The

desirable DU properties include the high mass density

(19070 kg/m3) and the adiabatic shear localization

(ASL) that occurs when rapidly loaded. High density

provides a benefit in energy and momentum transfer,

and ASL leads to a “self sharpening” of the projectile as

it penetrates armor plate rather than the less desirable

plastic deformation and “mushrooming” of the projectile

tip (thus degrading penetration depth). The Army has

tested several alternative materials, and, to date, the

best have been composites of tungsten powder within

metallic matrices. The 19,300 kg/m3 density of W

is close to DU and the ideal metallic matrix will have

properties such that the resulting composite fails with

ASL or ASL-like behavior. Recent work has shown that

BAM alloys have promise in providing the necessary

ASL-like behavior.

The need for large-size BAM components (> 10 cm

cross section) and suitable materials for the projectile

composites has resulted in an interest to produce BAM

alloy particles for subsequent consolidation. Atomization

of a pre-alloyed melt will produce fully amorphous

solidification in powder particles < 100 μm in diameter.

In addition, thermodynamic assessments of candidate

alloys will be used to study a range of amorphous

materials with the necessary mechanical properties.

Figure 1 shows the small-scale gas atomizer that was

built to study the composition-dependent solidification

behavior of BAM alloys using small batch (250 g)

processing to reduce material costs. Large-scale batch

processing of candidate compositions for consolidation

studies is then accomplished using the NIST 22 kg melt

capacity, gas-metal atomizer.

In order to take full advantage of the benefits

afforded by BAM alloys, powders must be consolidated

without inducing large-scale re-crystallization.

To understand the densification behavior of these

materials, a project was initiated to study the kinetics

of consolidation by pressure and heat below the

crystallization temperature. A hot isostatic press (HIP)

has been instrumented with a sensor developed at NIST

to follow densification. A warm isostatic press that

uses a liquid ester working fluid that can be pressurized

to 400 MPa (twice the pressure of the HIP) is also

being instrumented with a density sensor. These two

units provide quantitative, real-time monitoring of the

progress of densification.

Contributors and Collaborators

R.J. Fields, S.P. Mates, T. Pierce, S.D. Ridder

(Metallurgy Division, NIST); T. Zahrah, R. Rowland

(MatSys); D. Bowden (Boeing); L. Christodoulou

(DARPA); L. Kecskes (U.S. Army)

Advanced Manufacturing Methods

Figure 1: Small scale Laval atomizer for production of 250 g

lots of metal powder.
30

Program Overview

Combinatorial Methods

and online at www.nist.gov/combi. Within the

Materials Science and Engineering Laboratory (MSEL),

novel methods for combinatorial library preparation are

designed to encompass variations of diverse physical

and chemical properties, such as composition, film

thickness, processing temperature, surface energy,

chemical functionality, UV-exposure, and topographic

patterning of organic and inorganic materials ranging

from polymers to nanocomposites to ceramics to

metals. New instrumentation and techniques have

been developed that enable the high-throughput

measurements of adhesion, mechanical properties,

failure mechanisms, film thicknesses, and refractive

index, among others. The combinatorial effort

extends to multiphase, electronic, optoelectronic,

and magnetic materials, including biomaterials

assays. On-line data analysis tools, process control

methodology, and data archival methods are also

being developed as part of the Program’s

informatics effort.

The extensive outreach activity in the Combinatorial

Methods Program is designed to facilitate technology

transfer with institutions interested in acquiring

combinatorial capabilities. The centerpiece of this effort

is the NIST Combinatorial Methods Center (NCMC),

an industry–university–government consortium organized

by MSEL that became operational on January 23, 2002

via a kick-off meeting in San Diego. The recognized

importance of NCMC activities is readily apparent, as

15 industrial partners, the Air Force Research Lab, and

the University of Southern Mississippi are participating

in the NCMC membership program. The membership

continues to grow and 80% of the members from last

fiscal year have already renewed for this fiscal year.

The NCMC facilitates direct interaction between NIST

staff and these industrial partners, and it provides a

conduit by which Combinatorial Methods Program

research products, best practices and protocols,

instrument schematics and specifications, and other

combinatorial-related information can be effectively

disseminated. This outreach is mediated in large

part by a series of semi-annual workshops for

NCMC members. Indeed, since its inception,

four NCMC workshops have been held at NIST.

Further information on the NCMC can be found

on the website at www.nist.gov/combi.

Contact: Leonid A. Bendersky

The Combinatorial Methods Program develops

novel high-throughput measurement techniques and

combinatorial experimental strategies specifically

geared towards materials research. These tools

enable the industrial and research communities to

rapidly acquire and analyze physical and chemical data,

thereby accelerating the pace of materials discovery

and knowledge generation. By providing measurement

infrastructure, standards, and protocols, and by

expanding existing capabilities relevant to combinatorial

approaches, the Combinatorial Methods Program

lowers barriers to the widespread industrial

implementation of this new R&D paradigm.

The Combinatorial Methods Program has adopted a

two-pronged strategy for accelerating the development

and implementation of combinatorial approaches:

an active intramural R&D program and an ambitious

outreach activity. The intramural R&D program is

designed to better tailor combinatorial methods for the

materials sciences and extend the state-of-the-art in

combinatorial techniques. Measurement tools and

techniques are developed to prepare and characterize

combinatorial materials libraries, often by utilizing

miniaturization, parallel experimentation, and a high

degree of automation. A key concern in this effort is

the validation of these new approaches with respect

to traditional “one at a time” experimental strategies.

Accordingly, demonstrations of the applicability of

combinatorial methods to materials research problems

provide the scientific credibility needed to engender

wider acceptance of these techniques in the industrial

and academic sectors. The successful adoption of the

combinatorial approach also requires a highly developed

“workflow” scheme. All aspects of combinatorial

research, from sample “library” design and library

preparation to high-throughput assay and analysis,

must be integrated through an informatics framework,

which enables iterative refinement of measurements and

experimental aims. Combinatorial Methods Program

research projects give illustrations of how combinatorial

methodology is implemented effectively in a research

setting.

NIST-wide research collaborations, facilitated by

the Combinatorial Methods Program, have produced

a wide range of new proficiencies in combinatorial

techniques, which are detailed in a brochure,

“Combinatorial Methods at NIST” (NISTIR 6730),
31

Combinatorial Methods for Thin Films

In the search for new functional materials for

use in modern microelectronics, various thin

film oxides are under consideration. With the

ability to locally measure properties of the films,

combinatorial approaches using miniature thin

film assays of varying compositions can be

of significant impact to optimize the search.

The combinatorial methodology is still in its

early stages of development, and, therefore,

understanding the fundamentals of synthesis of the

combinatorial assays, as well as the relationships

between crystal chemistry and physical properties

of the assays, is of great importance.

Leonid A. Bendersky

The effectiveness of the combinatorial approach in

the development of thin film electronic materials has

been clearly demonstrated. In order to rapidly survey a

large compositional landscape, assays with continuously

changing compositions are synthesized, processed,

and screened in a single experiment. Dielectric,

magnetic, and other properties can be measured

within compositional spreads using recently developed

instruments with high spatial resolution, such as the

microwave microscope and microSQUID. In early

combinatorial materials research, the local microstructure

and phase composition were largely unprobed. Through

our ongoing collaboration with Professor Ichiro Takeuchi

from the University of Maryland, we have demonstrated

the value of using transmission electron microscopy

(TEM) for understanding the deposition process and

the correlations between physical properties and

local microstructure.

In 2003, our primary focus was on using

combinatorial research to demonstrate tunable bandgaps

by doping a semiconductor ZnO (bandgap: 3.3 eV,

hexagonal structure) with MgO (bandgap: 7.8 eV,

cubic structure). Potential applications are for optical

devices, including UV lasers, as well as transparent

conducting layers for solar cells and phosphors.

The Zn1–xMgxO thin film assays are prepared using

pulsed laser deposition (PLD) with synchronized

shutters. Multiple targets were alternatively ablated

for atomic layer-by-layer deposition onto substrates

with matching lattices, producing epitaxial films

compositionally uniform in the growth direction and

with one-dimensional compositional variation along the

film plane. These epitaxial spreads were studied for

bandgap by UV transmission and for microstructure

by scanning x-ray microdiffractometer and

transmission electron microscopy (TEM).

The results show a continuously changing bandgap

for x < 0.4 and x > 0.6, suggesting possibilities of using

the arrays themselves as photodetectors with a range

of detection frequencies separately active at different

locations within the film.

Scanning x-ray results showed three structurally

different regions. TEM gave insight into the structural

details. An especially important finding was for the

0 < x < 0.4 region where, according to the x-ray

diffraction, there is an extended solid solution of Mg

in ZnO. TEM, however, identified a high density

of planar defects and, according to high-resolution

imaging, the defects appear to be layers of (111) MgO

intergrown in the host lattice of ZnO (see Figure 1).

Thus the effect of Mg ions on the electronic structure

and bandgap of ZnO will be very different, at least

conceptually, from the solid–solution model.

Other active areas of research include developing

MOIF as a rapid imaging method to determine

ferromagnetic phase boundaries, establishing the

relationship between bulk properties and thin film

properties in shape memory alloys, and measuring

composition-dependent and structure-dependent

properties of multiferroic materials.

Figure 1: Epitaxial ZnO-based phase (containing 10 at % Mg)

with a high density of extended planar defects. HRTEM image

showing the stacking fault-type nature of the defects and

suggesting an accommodation of the excess MgO on the defect.

Contributors and Collaborators

I. Takeuchi, K.-S. Chang (University of Maryland);

M.J. Turchinskaya, R. Parke (Metallurgy Division,

NIST)

Combinatorial Methods
32

Phase Diagrams for III–V Thin Films and Metal Contacts

Commercialization of Group III nitride devices

has been hindered by several technological and

fundamental materials issues, including problems

with making high quality GaN epilayers and

bulk substrates and with fabrication of reliable

electrical contacts. This project focuses on

experimental and computational evaluation

of Metal – Group III – N phase diagrams to be

used as a roadmap for: a) optimization of growth

and thermal processing of GaN and related

nitrides and for; b) development of metallization

information to enable the design of improved

electrical contacts to GaN-based devices. For

metallizations, a combinatorial approach is

used for establishing the relationship between

electrical properties, metallization compositions,

and processing parameters.

Albert Davydov and William Boettinger

Gallium nitride-based semiconductors are used in

 blue-green and UV lasers, LEDs, photodetectors,

and high-temperature/high-power electronic devices.

The optimum growth conditions of GaN, choice of

contact metals, and thermal processing limits for the

device structures rely mostly on trial-and-error

methods and are not fully understood. We believe that

knowledge of the thermodynamics/kinetics in Metal –

Group III – N systems can provide guidance for

optimization of the device processing parameters.

In the Ga-N system, we use experimental and

computational CALPHAD procedures to evaluate the

thermodynamic and phase diagram data (Figure 1).

A thermodynamically consistent model representation

of the available data and our experimentally determined

properties have resulted in reasonable estimates of

missing critical data, such as melting/decomposition

temperature of GaN as a function of nitrogen

pressure. Results are now posted on the ONR

National Compound Semiconductor Roadmap

website (http://ncsr.csci-va.com) and can be used

in optimizing growth and processing conditions

for GaN-based devices.

In 2003, the utility of phase diagrams in analyzing

metallization choices was demonstrated using Ni as

one of the most commonly used industrial contacts.

The Ni-Ga-N phase diagram was calculated and verified

experimentally (Figure 2). The diagram was used to

interpret the interfacial reactions in the Ni/GaN thin film

structures (see Figure 3). An experimental combinatorial

study of Ni/Au metallization to GaN is now underway.

Contributors and Collaborators

L. Bendersky, U. Kattner, F. Biancaniello, D. Josell,

A.J. Shapiro (Metallurgy Division, NIST); T.J. Anderson,

O. Kryliouk (Univ. of Florida); S. Noor Mohammad

(Howard University); M. Master (TDI, Inc.)

Figure 1: Calculated Ga-N phase diagram with superimposed

isobaric lines (dashed).

Figure 2: Experimental data (points and arrows) and

calculated (lines) for the Ni-Ga-N phase diagram.

Figure 3: XRD of Ni/GaN thin film structure (overcoated

with Au) annealed at 800 °C: Ni3Ga and Ni2Ga3 are formed.

Combinatorial Methods
33

Program Overview

Data and Data Delivery

The economic importance of technical data has

grown steadily over the past three decades. NBS/NIST

took an important lead early in the effort to emphasize

the pervasive use and increase the impact of reliable

materials property data. As early as 1985, former NBS

Director E. Ambler noted that the need for property

data had become a “national priority,” while the

National Research Council repeatedly observed that

there is a persistent “critical national need” for

materials property data.

The NIST Materials Science and Engineering

Laboratory (MSEL) has been a prominent leader in

responding to this national need. By design, the scope

of the MSEL effort is evolutionary and responds to the

ever-increasing advances in technology. Currently,

MSEL has six project areas in the Data and Data

Delivery program.

■ Crystallographic and Phase Equilibria Databases

[Project Leader — V. Karen]: This project

encompasses the two most venerable efforts in

MSEL, each of which recently has had a major new

release. In collaboration with Fachinformationszentrum

Karlsruhe (FIZ, Germany), a CDROM version of

the FIZ/NIST Inorganic Crystal Structure Database

(ICSD) has been released providing the full structural

data, i.e., lattice parameters and atomic coordinates,

for approximately 60,000 compounds. The

long-standing collaboration between NIST and the

American Ceramic Society (ACerS) has continued

with the completion of a new topical volume in the

NIST/ACerS Phase Equilibria Diagrams series, the

first of two planned volumes on electronic ceramics.

■ Phase Equilibria and Properties of Dielectric

Ceramics [Project Leader — T. Vanderah]:

An integrated theoretical and experimental effort is

underway to predict and measure phase equilibria

and electronic behavior in dielectric oxide systems.

This work includes relaxor ferroelectrics, dielectrics

for cellular infrastructure and hand-held devices, and

dielectrics for low temperature co-fired ceramics for

applications in multilayer ceramic integrated circuit

technology. The impact of this work was evident in

Dr. Vanderah’s invited perspective article, “Talking

Ceramics,” which appeared in the journal Science.

The timeliness of this work was emphasized further

by its subsequent feature in the science section of

the New York Times.

■ Phase Relationships in High Temperature

Superconductors [Project Leader — W. Wong-Ng]:

MSEL’s meticulous effort to provide phase information

critical to the development of practical superconductors

is currently directed towards two important systems:

Ba2RCu3O7–x, where R is yttrium or a lanthanide,

and MgB2. For Ba2RCu3O7–x, work has focused on

the phase relations in BaF2-BaO-Y2O3-CuOx-H2O and

the interactions of Ba2RCu3O6+x with buffer layers,

both of which are important for advances in the

“BaF2 ex situ” process and the “liquid-phase-epitaxy”

process. For MgB2, the enthalpy of formation,

vapor pressure, and sources of variability have

been determined.

■ Reaction Path Analysis in Multicomponent Systems

[Project Leader — C. Campbell]: Many industrial

processes rely on multicomponent diffusion to

control the formation and dissolution of precipitate

phases. MSEL is developing a multicomponent

diffusion mobility database for Ni-base superalloys

that will be used, for example, to predict the

formation of the γ′ (ordered FCC) phase during the

solidification of superalloys. A workshop, “High

Throughput Analysis of Multicomponent Multiphase

Diffusion Data,” was held in March 2003 to focus

on the development of methods to extract diffusion

data from multicomponent diffusion couples. 

■ Evaluated Materials Property Data [Project

Leader — R. Munro]: Engineering designs utilizing

advanced materials require reliable data. Elasticity,

strength, toughness, hardness, creep, thermal

expansion, conductivity, diffusivity, and durability

are prominent among the data categories needed and

desired for materials applications and development.

This project is directed both towards the development

of evaluated databases of these properties for

structural and superconducting ceramics and towards

the establishment of the evaluation methodologies that

form the foundation of reliable materials property

data systems. A significant achievement in this

effort is “Data Evaluation Theory and Practice for

Materials Properties,” SP960-11, the eleventh NIST

Recommended Practice Guide produced by MSEL.

■ Informatics and Visualization in Materials

Data Delivery [Project Leader — C. Beauchamp]:

The internet, and the World Wide Web in particular,

has become a dominant resource medium for

technical information. MSEL has undertaken a

major commitment to make its extensive data

collections available via this medium. New efforts,

now underway, will provide web access to the MSEL

lead-free solder materials property database and

the diffusion data archive that is important for the

processing of metal alloys. Additionally, the internet

will be used increasingly as a means of disseminating

MSEL’s prodigious technical publications in the form

of electronic manuscripts.

Contact: Carlos R. Beauchamp
34

Informatics and Visualization in Materials Data Delivery

Success in implementing a reliable materials

design is dependent on access to accurate and

reliable properties data. With the shortened cycle

between product concept and commercial rollout

and the increased permutations of materials

choices, being able to deliver critically evaluated

data in a timely manner has become one of the

prime objectives of the Metallurgy Division.

Efforts are concentrated on using the World Wide

Web to deliver, in standard format such as MatML

(a standard materials mark-up language), the

data gathered across all projects.

Carlos Beauchamp and Carol Handwerker

The effectiveness of searching electronic databases

is presently hampered by the lack of materials data

that is properly formatted to enable such searches.

To address those needs, the Metallurgy Division has

embarked on two major projects to make collections

of critically evaluated data available on the Internet.

The first of these projects addresses the collection

of over 25,000 international papers, theses, and

government reports on diffusion published before 1980

and warehoused in the NIST Diffusion Data Center in

printed form. The recent NIST-sponsored workshops

on “Databases for Computational Thermodynamic and

Diffusion Modeling,” (March 2002) and on “High

Throughput Analysis of Multicomponent Multiphase

Diffusion Data,” (March 2003) highlighted the need for

access to the diffusion data stored at the Center to be

able to proceed with the development of multicomponent

diffusion databases, which are based on binary and

ternary diffusion data already contained there and

with the modeling of diffusion-controlled processes.

Work is underway to convert the bibliographical

data contained in the collection into electronically

searchable data that will be available through a

designated link in the Division homepage.

The second of these efforts addresses the need for

a better understanding of the mechanical properties

of lead-free solder alloys and their thermo-mechanical

responses (e.g., Figure 1). This knowledge is required

for the implementation of accelerated test plans, predictive

reliability models, and product reliability assessment.

The service life of solder joints is limited by the fatigue

damage accumulated in the material. The reliability analysis

used to predict the service life of solder joints under use

conditions, based on accelerated tests, depends on life

prediction models based on SnPb assemblies. Similar

models are non-existent for the lead-free solders due

to the lack of understanding of failure modes, adequate

constitutive models, and reliability databases that correlate

failure times under test with real field conditions.

The Division is committed to providing a quantitative

review of the thermo-mechanical properties of lead-free

solders, emphasizing the SnAgCu system, the choice

of alloy for reflow assemblies, and the SnAg system,

recommended for wave-soldering applications. The

results of the report are in the process of being converted

into electronically available data, along with the complete

report, through the Division’s homepage.

Additional efforts in MSEL include:

■ Developing approaches for viewing multidimensional

mechanical property and phase diagram data for

metals;

■ Continued support for the development and

implementation of MatML, a materials mark-up

language;

■ Compiling elastic moduli data for polycrystalline

oxide ceramics;

■ Completing the Inorganic Crystal Structure Database

(in cooperation with Fachinformationszentrum,

FIZ, Germany); and

■ Producing phase diagrams through NIST/American

Ceramic Society Phase Equilibria Program.

Contributors and Collaborators

W.J. Boettinger, C.E. Campbell, K. Dotterer,

R. Drew, R. Fields, H. Gates, F. Gayle, U.R. Kattner,

K.-W. Moon, S. Tobery (Metallurgy Division, NIST);

J.-C. Zhao (GE); J.P. Clech (EPSI, Inc.)

Figure 1: Sn-3.5Ag lap shear and plug & ring data.

Data and Data Delivery
35

Reaction Path Analysis in Multicomponent Systems

Many commercial processes rely on multicomponent

diffusion to control the formation and dissolution

of precipitate phases within the matrix phase or at

interfaces. This project develops diffusion mobility

databases that provide efficient methods of storing

a wealth of diffusion data and enable extrapolation

of the available data to higher-order systems.

Carelyn E. Campbell and William J. Boettinger

Multicomponent diffusion controls many industrial

 processes, especially in the processing and

application of Ni-based superalloys. An improved

understanding of diffusion-controlled microstructures

would aid optimization of heat treatments that avoid

incipient melting and would enable the prediction

of freezing temperatures and solidification paths

for systems such as Ni-based superalloys. These

processes require mobility databases to describe

the composition-dependent diffusion coefficients.

The NIST composition-dependent mobility database

has been constructed using an approach that assumes

that quaternary and higher-order interactions are

negligible. Thus, binary and ternary effects can be

combined to extrapolate to higher-order systems.

For application to nickel-based superalloys, we have

constructed a database for the γ (disordered FCC)

phase of the Ni-Al-Cr-Co-Fe-Hf-Mo-Nb-Re-Ta-Ti-W

system. The database was published in Acta Materialia

in 2002 where it is readily available to industry. General

Electric Corporate Research and Development (GE-CRD)

and Howmet Corporation provided experimental results

from multicomponent diffusion couples which were

compared with diffusion simulations. The experimental

and calculated diffusion composition profiles for the

Rene88/IN718 diffusion couple agree quite well, as

shown in Figure 1. The current database is now

being refined based on experimental work from GE-CRD.

Two applications of this work are mentioned here.

As a part of a GE-led DARPA /Advanced Insertion of

Materials project, NIST supplies composition dependent

diffusivity data for the γ matrix that team member

Questek Innovations uses in numerical modeling of

the γ′ precipitation process. NIST has also initiated

an effort to develop heat treatment optimization

techniques to address industry’s need for more efficient

heat-treating practices of cast Ni-based superalloys.

The ideal heat treatment of a cast Ni-base superalloy

consists of a heating schedule that avoids incipient

melting while minimizing either the power expenditure or

the heating time to achieve a homogeneous single-phase

structure. For the solidified Rene-N4 composition

profile calculated using a constant cooling rate of

1 K/s, Figure 2 shows the predicted incipient melting

temperature as a function of linear heating rates.

Contributors and Collaborators

U. Kattner (Metallurgy Division, NIST);

J.-C. Zhao (GE-CRD); T. Hansen (Howmet);

C. Kuehmann (Questek Innovations); Z.K. Liu

(Penn State); D. Seidman (Northwestern University)

Figure 1: Calculated (solid lines) and experimental (symbols)

composition profiles for the Rene88 / IN718 diffusion couple at

1150 oC for 1000 h. (Experimental data from GE-CRD.)

Figure 2: For Rene-N4, the predicted incipient melting

temperature (K) as function of linear heating rates.

Data and Data Delivery
36

Program Overview

Nanocharacterization

The emphasis on nanotechnology around the world

and the successful implementation of the National

Nanotechnology Initiative in the U.S. are accelerating

the development of science and technology at the

nanoscale. Nanotechnology is expected to play a key

role within the next 10 years in a wide spectrum of

industry sectors including manufacturing, information

technology, electronics, and healthcare. Novel devices

at the micro- and nanoscale will become increasingly

important in all of these industries. The ability to

measure dimensions, characterize materials, and

elucidate structures of new and novel materials at

the nanoscale will be critical to the advancement of

nanotechnology. In addition, one of the exciting

prospects of nanotechnology lies in the ability of

molecules or particles, under specific conditions, to

self-assemble to form new materials with unusual

properties. Successful development of these new

materials will require the ability to monitor such

processes at the nanoscale in real time. Metrology,

the science of measurement, is therefore the foundation

of nanotechnology. Standards and reference materials

will also provide essential infrastructural support to

this emerging technology.

The objective of the program in the NIST Materials

Science and Engineering Laboratory (MSEL) is to

develop basic measurement metrology at the nanoscale

for the determination of bulk and surface material

properties and for process monitoring. Measurement

methods are being developed for use in conjunction

with new instrumentation and calibration artifacts.

The scope of the program encompasses metals,

ceramics, and polymers in various forms — particles,

thin films, nanotubes, and self-assembled structures

— and also includes studies of nanocomposites

and liquid-state properties for microfluidics-based

fabrication and measurement techniques. Physical

properties such as mechanical strength, elastic moduli,

friction, stiction, adhesion, and fatigue strength

are measured, as well as the size of nanoparticles

and the structure and dispersion behavior of

nanoparticulate systems. Other properties such

as electrical conductivity, thermal conductivity,

magnetic properties, electronic properties, and

optical properties are also examined. While the

program focuses on developing measurement

techniques at the nanoscale, proper data interpretation

requires fundamental studies in nanomechanics,

scaling laws, and imaging techniques.

There are currently ten projects under the program:

■ Bridging Length Scales in Theory and Modeling;

■ Electrochemical Processing of Nanoscale Materials;

■ Metrology for Nanoscale Properties;

■ Nanofiller Processing;

■ Nanoindentation;

■ Nanomechanics and Standards;

■ Nanoscale Manufacturing;

■ Nanotribology and Surface Properties;

■ Particle Metrology and Standards; and

■ Physical Properties of Thin Films and Nanostructures.

In many of these individual projects, objectives

are directed toward the study of a particular class of

materials or material properties, but the underlying

theme of the program as a whole is to develop

reliable, accurate measurement techniques for a

broad range of materials and material properties at the

nanoscale. As just one example, four methods for the

determination of the elastic properties of thin films —

atomic force acoustic microscopy, surface acoustic

wave spectroscopy, Brillouin light scattering, and

nanoindentation — are being compared using common

sets of specimens. This study will lead to a better

understanding of the complementary nature of these

techniques for measuring nanostructured materials

and their combined use to determine supplementary

properties such as film thickness or density. Standard

reference materials are being developed in collaboration

with other National Measurement Institutes around the

world for use in the verification of the performance

of these instruments.

Contact: James A. Warren
37

Bridging Length Scales in Theory and Modeling:

Microstructure Evolution and Material Mechanics

The performance of many structural and

functional materials depends on the distribution of

composition, phases, grain orientations, internal

stresses, and microstructure on length scales from

nanometers to meters. Industry needs predictive

models to reduce the enormous costs and

development times involved in designing and

inserting new materials into state-of-the art products.

To address these needs, we are developing phase

field models of solidification and solid-state

transformations, with coupling to stress, grain

orientation and solute/vacancy dynamics.

James A. Warren and William J. Boettinger

I

n order to model the complex interfacial shapes that

 produce real microstructures, the phase field method

has become the technique of choice for computational

materials scientists.

Modeling of microstructures produced by processing

of materials involves solution of mathematical equations

for heat flow, deformation/fluid flow, and /or solute

diffusion. Boundary conditions on external surfaces

reflect the macroscopic processing conditions that

can be externally controlled. In classical models of

materials processing, boundary conditions on internal

interfaces corresponding to the liquid–crystal (grain),

grain–grain and/or phase–phase interfaces reflect

material thermodynamic and kinetic conditions. For

solid–solid transformations, stress effects also become

significant, and surface stresses become particularly

important in nanoscale microstructures. Phase field

models finesse the difficult numerical task of tracking

moving internal interfaces by the introduction of a new

variable, the phase field.

Research in phase field modeling conducted in the

Metallurgy Division is also supported by the NIST

Center for Theoretical and Computational Materials

Science. Recent efforts have focused on bringing

together many of the disparate efforts in phase field

modeling to create a unified picture of materials

processing with a single set of equations governing

microstructure evolution. In the past year we have:

■ Developed a model of a stressed system containing a

curved interface between two phases with different

elastic properties. This model has been applied to a

liquid (zero shear modulus)–solid system.

■ Simulated 3-D fault dynamics in directionally

solidified binary eutectics.

■ Combined phase field models of eutectic colony

growth with polycrystalline structures. This approach

readily deals with complex interface shapes and

topology changes (see Figure 1).

■ Simulated the growth of dendrites in polymers where

crystallographic rotation of the growth direction

occurs, “dizzy dendrites” (with the Polymers Division).

■ Prepared an overview of phase field modeling of

polycrystalline growth and coarsening (Acta

Materialia, in press).

Figure 1: A simulation of eutectic colony growth. The colors

indicate crystal orientation. The solid phase can be distinguished

as large regions of a single color while the liquid appears

essentially random in orientation at the smallest scales.

While this research is ambitious in its scale, the

successes so far suggest that the goals are within

reach. Work to be done includes joining the stress

models with existing models of polycrystalline growth,

the addition of vacancies to all of these models in a

thermodynamically consistent manner, the extension of

the grain boundary model to three dimensions, and the

coupling of all of these effects to fluid flow.

Contributors and Collaborators

J. Warren, W. Boettinger, D. Lewis, J. Guyer,

R.F Sekerka (Metallurgy Division, NIST); J. Douglas

(Polymers Division, NIST); J. McFadden (Mathematical

and Computational Sciences Division, NIST); J. Slutkser,

A. Roytburd (University of Maryland); R. Kobayashi

(Hokkaido University, Japan); L. Granasy (RISSPO,

Hungary)

Nanocharacterization
38

Electrochemical Processing of Nanoscale Materials

Precise temporal control of supersaturation

provided by electrochemical methods holds

promise for the synthesis and characterization of

materials and structures of very small dimensions

— nanomaterials. Variation of the electrochemical

potential leads not only to changes in the metal

deposition rate but also effects the adsorption of

surfactants and segregation phenomena which

exert a strong influence on the morphological

evolution and stability.

Thomas P. Moffat and Jon Mallett

Electrochemical synthesis has become an important

 tool in the fabrication of nanoscale devices and

structures. Modulation of the electrode potential can

be used to create films with a corresponding variation

in composition and/or structure. This allows materials,

such as multilayers and nanocontacts, to be engineered

with submonolayer precision. Likewise, knowledge of

the stability and reliability of these finite size structures

will be central to any technical application.

 In the last year, we have continued using scanning

probe microscopy to characterize the structure and

stability of immersed surfaces. This work ranges

from atomically resolved STM studies of adsorbate

dynamics to AFM measurements of roughness evolution

during electrodeposition. The focus of this activity is

strengthening our knowledge of the connection between

atomistic processes and morphological evolution

observed at larger length scales.

A new aspect of our program this year is the study

of nanocontacts formed by electrodeposition between

two electrodes. Physical property measurements of

these junctions have revealed a variety of effects such

as quantized conductance, ballastic magnetoresistance,

and adsorbate-influenced surface scattering. Many

investigations use electrodeposited contacts, yet limited

techniques are available for growing and maintaining

such junctions at a fixed or predetermined conductance.

At NIST, we have combined a bipotentiostat with

a STM-like feedback circuit in order to form

electrodeposited metal contacts of predetermined

fixed resistance.

Figure 1: A high resolution STM image of a c(2x2) chloride

adlayer on Cu(100) in 0.01 mol/L HCl. The image was collected

at –0.150 V SCE as shown on the inset voltammogram.

Figure 2: Schematic of control circuit used for forming and

maintaining contacts of fixed conductance.

Figure 3: Controlled step in nanocontact resistance.

The junction conductance measured with a

lock-in-amplifier is compared with a preset value,

and the electrochemical potential of the two working

electrodes is adjusted to either deposit or etch material

to obtain the specified conductance value. Figure 3

shows a controlled transition in contact resistance

between 778 Ω and 369 Ω. Careful choice of the

feedback control parameters resulted in transients

with only one damped oscillation. Stable contacts

have been grown between 800 Ω and 2 Ω.

In the coming year, the measurements outlined

above will be extended towards problems relevant to

micro- and molecular electronics.

 Contributors and Collaborators

W.F. Egelhoff, H. Ettedgui, E.B. Svedberg,

J.E. Bonevich, R.D. McMichael (Metallurgy Division,

NIST)

Nanocharacterization
39

Program Overview

Interface of Materials with Biology

New materials and devices are radically

changing the medical treatment of injury and disease,

yet because of the rapid pace of this segment of

the materials industry, an adequate measurement

infrastructure does not yet exist. The program

on the Interface of Materials with Biology develops

measurement methods, standards, and fundamental

scientific understanding at the interface between

materials science and biological science. Within the

health care industry, we focus on dental and medical

sectors that apply synthetic materials for replacement,

restoration, and regeneration of damaged or diseased

tissue. Three primary foci exist within this program:

biocompatibility, materials properties, and materials

science techniques applied to biological systems.

Whether the medical issue involves implanting

a hip or knee joint prosthesis, a synthetic bone graft,

or a tissue engineering scaffold into the human body,

one of the primary issues is biocompatibility. By using

our expertise in materials science, we are working

to develop suitable Reference Materials (RM) for

investigating biocompatibility and implant suitability.

Research has focused on measuring the cellular

response to powders and bulk materials to identify

suitable candidates. We are collaborating with the

American Dental Association Foundation (ADAF)

to develop metrology methods to characterize the

biocompatibility of synthetic bone grafts. Quantitative

methods being developed include assays for adhesion,

viability, proliferation, and differentiation of bone cells,

as well as optical coherence tomography and confocal

microscopy for measuring tissue ingrowth. We are

developing biochemical assays to quantify inflammatory

responses to synthetic materials. Finally, current

research is working to bridge the gap between

knowledge generation by cell biologists and product

development in industry. In collaboration with the

Chemical Science and Technology Laboratory, we are

developing measurement methodologies and reference

materials to use in assessing interactions in complex

systems of living cells with synthetic materials.

The expected outcomes of this work are reference

substrates that induce specific cellular responses and

engineered DNA vectors to act as fluorescent reporters

of cellular responses.

In addition to the issue of biocompatibility, it is

critical that the materials can withstand the mechanical

and environmental stresses placed on them. For

metallic implants, one concern is the corrosion pitting

resistance of the implant materials and the associated

potential for stress corrosion cracking (SCC). To

address this issue, metal standards are being subjected

to a simulated biological environment which will then

be used to develop tests to assess the susceptibility

for SCC.

Mechanical properties issues also arise when

considering synthetic bone grafts and tissue engineering

scaffolds. In addition to traditional bulk mechanical

property measurements, combinatorial approaches

are used to identify compositions and surface features

that affect properties such as biocompatibility and

mechanical durability. Finally, because the dental

industry is primarily composed of small manufacturers

with limited R&D capability, collaborations with

the ADAF, located in MSEL, are filling the gap

by developing improved materials and techniques,

patenting and licensing these inventions, and, most

importantly, providing a technical foundation.

Research focuses on improved understanding

of the synergistic interaction of the phases of

polymer-based composites and the mechanisms of

adhesion to dentin and enamel. This approach will

ultimately lead to materials with improved durability,

toughness, and adhesion to contiguous tooth structure.

In this era of interdisciplinary approach to

research, we provide an added dimension. By taking

a physical/mechanical approach to how cells function,

respond, and remodel in interaction with synthetic

materials, we can provide skill sets typically absent

in the biomedical community. Our concentration on

mechanical property metrology extends to biological

systems, spanning a considerable size range from

individual neurons and muscle cells to complete

pulmonary arteries. This necessitates the development

of unique mechanical testing platforms and application

of a materials science approach to understanding

integrated properties.

Fundamental to much of the work in this program

is the recognition that surfaces and interfaces play a

critical role in biological systems and, in particular,

in the interactions of synthetic or designed materials

with biological systems and function. By applying

the expertise in the NIST Materials Science and

Engineering Laboratory to characterization of surfaces

and interactions at interfaces in biomaterials, we will

accelerate the introduction of improved materials and

help provide the means to assure quality control that is

critical to this industry.

Contact: Frank S. Biancaniello
Interface of Materials with Biology

Biocompatibility of Metals Reference Powders

1) ingot processed 316L (medical grade stainless steel

for orthopaedic fixtures and screws); 2) PM processed

316L; and 3) PM processed High Nitrogen Stainless

Steel (HNSS).

The medical implant device industry needs

characterized metal particles to be used in

evaluating the effect of debris released by metallic

implants. There is also a need to determine what

surface characteristics are needed in metallic

implants to improve biocompatibility. This research

is developing expertise directed at investigating

the biocompatibility and implant suitability of

Powder Metallurgy (PM) processed 316L stainless

steel (SS), PM processed High Nitrogen SS, and

traditional ingot processed 316L SS.

Frank Biancaniello and Stephen Ridder

Roughly two billion dollars are spent each year in

 the United States on metallic medical implants.

These include the large variety of hip and knee joint

prostheses, dental implants, plates and pins for broken

bones, vascular stents, and other reconstructive

devices. Evaluation of the biomechanical performance

of these devices involves in vitro and in vivo tests

to access the suitability of a metal alloy chemistry

or component design for its intended application.

For example, artificial hip and knee joints are tested to

determine strength, rate of joint wear, biocompatibility

of wear debris, and nature of ingrowth at the implant/

bone interface. Comparisons of results from various

laboratories are hindered by the lack of suitable

reference materials to quantify biomechanical

performance.

Gas atomized metal powders are an ideal source

of particulate metallic materials for clinical testing.

In addition, consolidated metal powder provides a

means to generate reproducible reference metallic

substrates with the enhanced chemical homogeneity

and grain refinement found in PM processed materials.

In the Metallurgical Processing Laboratory, we have

the best instrumented gas atomization facility in the

U.S., specifically designed to control particle size,

solidification rate, and microstructure. In this small

scale project, we are examining the utility of using

well-controlled, gas-atomized powders produced at

NIST as reference materials through an evaluation of

metal powders and bulk metal specimens using several

standard biocompatibility test methods. Genotoxicity

will be determined using a bacterial reverse mutation

assay (Ames Test), and acute cytotoxicity will be

evaluated by the MTT cell proliferation assay using

mouse fibroblasts.

During 2003, these biocompatibility experiments

were run on three metallic powder and bulk materials:

Figure 1: Mouse macrophage proliferation on (a) ingot

processed 316L; (b) PM 316L; and (c) PM HNSS.

Preliminary results of a study of a mouse

macrophage proliferation on SS substrates are shown

in Figure 1. The spheroidized and necrotic cells on the

ingot processed 316L substrate in Figure 1a indicate

significant incompatibility; whereas the same cell line

has adhered to the surface and proliferated on PM

HNSS (Figure 1c), showing normal macrophage

morphology. An intermediate result (some cells

spherodized, others normal) was found on the PM 316L

(Figure 1b). Compatibility studies on SS alloys will

continue next year as well as including similar studies

on the other two common implant alloys, Co-Cr-Mo

and Ti-6Al-4V.

Another aspect of this project is the evaluation of

the corrosion-pitting resistance of metallic implant

materials. Previous NIST results indicate that PM

HNSS has a remarkable resistance to pitting under a

wide range of environmental conditions. While the

observed enhancement may be the result of the high

nitrogen content in these alloys, it could also be due to

the fine grain size and improved homogeneity inherent

to the rapid solidification process itself. To help

separate these effects, electrochemical behavior of ingot

processed 316L, PM 316L, and PM HNSS material is

now being evaluated in a simulated human environment

(i.e., Hank’s solution at 37 °C). The results of the

electrochemical evaluations will then be used to design

a series of slow strain rate (SSR) tensile tests that will

assess the susceptibility to stress corrosion cracking

(SCC) under the same environmental conditions.

Contributors and Collaborators

R. Jiggetts, S. Mates, M. Stoudt (Metallurgy

Division, NIST); L. Bailey, N. Washburn (Polymers

Division, NIST); F. Eichmiller, S. Gruninger (ADA);

J. Spicer, J. Lee (Johns Hopkins University); S. Ehrman,

T. Holoman (University of Maryland); A. Fischer

(University of Duisburg, Germany)

40
Program Overview

Materials for Micro- and Opto-Electronics

U.S. microelectronics and related industries

are in fierce international competition to design and

produce smaller, lighter, faster, more functional,

and more reliable electronics products more quickly and

economically than ever before. At the same time, there

has been a revolution in recent years in new materials

used in all aspects of microelectronics fabrication.

Since 1994, the NIST Materials Science and

Engineering Laboratory (MSEL) has worked closely

with the U.S. semiconductor, component, packaging,

and assembly industries. These efforts led to the

development of an interdivisional MSEL program

committed to addressing industry’s most pressing

materials measurement and standards issues central

to the development and utilization of advanced

materials and material processes. The vision that

accompanies this program — to be the key resource

within the Federal Government for materials metrology

development for commercial microelectronics

manufacturing — may be realized through the

following objectives:

■ Develop and deliver standard measurements and data;

■ Develop and apply in situ measurements on materials

and material assemblies having micrometer- and

submicrometer-scale dimensions;

■ Quantify and document the divergence of material

properties from their bulk values as dimensions

are reduced and interfaces contribute strongly

to properties;

■ Develop models of small, complex structures to

substitute for or provide guidance for experimental

measurement techniques; and

■ Develop fundamental understanding of materials

needed in future micro- and opto-electronics.

With these objectives in mind, the program

presently consists of projects led by the Metallurgy,

Polymers, Materials Reliability, and Ceramics

Divisions that examine and inform industry on key

materials-related issues. These projects are conducted

in concert with partners from industrial consortia,

individual companies, academia, and other government

agencies. The program is strongly coupled with

other microelectronics programs within government

and industry, including the National Semiconductor

Metrology Program (NSMP) at NIST. Materials

metrology needs are also identified through industry

groups and roadmaps, including the International

Technology Roadmap for Semiconductors (ITRS),

the IPC Lead-free Solder Roadmap, the National

Electronics Manufacturing Initiative (NEMI) Roadmap,

the Optoelectronics Industry Development Association

(OIDA) roadmaps, and the National [Magnetic Data]

Storage Industry Consortium (NSIC).

Although there is increasing integration

within various branches of microelectronics and

optoelectronics, the field can be considered in three

main areas. The first, microelectronics, includes

needs ranging from integrated circuit fabrication to

component packaging to final assembly. MSEL

programs address materials metrology needs in

each of these areas, including lithographic polymers

and electrodeposition of interconnects, electrical,

mechanical, and physical property measurement

of dielectrics (interlevel, packaging, and wireless

applications), and packaging and assembly processes

(lead-free solders, solder interconnect design, thermal

stress analysis, and co-fired ceramics).

The second major area is optoelectronics, which

includes work which often crosses over into electronic

and wireless applications. Projects currently address

residual stress measurement in optoelectronic films,

optical and structural characterization of wide bandgap

semiconductors, and standards development for

III–V compound semiconductors. Cross-laboratory

collaborations with EEEL figure prominently in

this work.

The third area is magnetic data storage, where

the market potential is vast and growing and the

technical challenges extreme. NSIC plans to

demonstrate a recording density of 1 terabit per

square inch — 40 times today’s level — by 2006.

To reach these goals, new materials are needed that

have smaller grain structures, can be produced as thin

films, and can be deposited uniformly and economically.

New lubricants are needed to prevent wear as spacing

between the disk and head becomes smaller than the

mean free path of air molecules. Some measurements

require calibration of magnetometers using certified

magnetic standards in several different shapes and

magnetic strengths, and with a wide range in magnetic

character. MSEL is working with the magnetic

recording industry to develop measurement tools,

modeling software, and standards to help achieve

these goals, with MSEL, the Electronics and Electrical

Engineering Laboratory, the Physics Laboratory,

the Information Technology Laboratory, and the

Manufacturing Engineering Laboratory working as

partners in this effort.

Contact: Frank W. Gayle

41
42

Superconformal Film Growth: Measurement and Modeling

These results are of fundamental importance in the

fabrication of high-aspect ratio advanced metallizations

because smooth surfaces on the metal deposits are

required for defect-free feature filling (Figure 2).

Furthermore, these results provide understanding and

direction in all electrodeposition processes providing

brightening.

Contributors and Collaborators

D. Wheeler, S. Coriell, J. Mallett, W. Schwarzacher

(Metallurgy Division, NIST); G. McFadden (Mathematical

and Computational Sciences Division, NIST)

Figure 1: The impact of catalyst concentration in the electrolyte

on the minimum wavenumber for which a perturbation is stable

(circles and squares are for different overpotentials). Substantial

improvement in the range of conditions for which the surface is

stabilized (up to two-orders of magnitude decrease of the critical

wavelength) is evident.

Figure 2: Superconformal copper electrodeposition. Trench

width is approximately 50 nm at mid-height. Note the smooth

sidewalls.

State of the art manufacturing of microelectronic

devices relies on superconformal deposition of

copper in fine trenches and vias for on-chip

wiring, or “interconnects.” The NIST-developed

Curvature Enhanced Coverage Mechanism is now

used by industry to understand this superfilling

process. More recent NIST research has

demonstrated that the same mechanism explains

the impact of catalysts on smoothing of surfaces

during all types of electrodeposition. This is the

first explanation of the surface stabilization

process, a phenomenon that is as important for

the filling of high aspect ratio features as the

bottom-up superfill process itself.

Thomas P. Moffat and Daniel Josell

This project continues to explore novel, advanced

means of meeting needs of the microelectronics

industry for improved device metallizations. Much

of the effort focuses on the Curvature Enhanced

Accelerator Coverage mechanism originally shown

by NIST researchers to explain “superconformal”

(or bottom-up) feature filling with copper. The CEAC

mechanism accounts for the impact of changing

surface area on the coverage of adsorbed additives

used in electrodeposition processes. Studies of this

mechanism continue to yield exciting new discoveries.

One particular result serves especially well to

demonstrate the breadth of the superfill studies and

the striking generality of the CEAC mechanism.

Researchers in the Metallurgy Division previously

demonstrated the ability of the CEAC mechanism to

explain key aspects of the bottom-up feature filling

process that is known in the integrated circuit industry

as “superfill.” They have also extended it to superfill

during electrodeposition of silver and chemical vapor

deposition of copper. The CEAC mechanism has

now been successfully extended to explain surface

stabilization during electrodeposition of metals in

electrolytes containing surfactant additives (Figure 1).

Such generality had been proposed in CEAC

publications on feature superfill, but until this work,

it had not been analyzed or proven. These results

quantify the effect using a linear perturbation analysis;

experimental evidence to support the model is also

presented. Significantly, these results explain why

remarkably dilute of additives known as “brighteners”

or “accelerators” are so effective at preventing the

roughening of surfaces even in the presence of

destabilizing metal ion concentration gradients in

the electrolyte.

Materials for Micro- and Opto-Electronics
43

Lead-free Surface Finishes: Tin Whisker Growth

The U.S. microelectronics industry is moving

towards Pb-free assemblies but lacks needed

measurements and data comparable to that

existing for Sn-Pb alloys. Protective layers, such

as “pretinned” coatings on Cu leadframes and

connectors, are required to maintain solderability

of components during storage prior to assembly.

A critical problem addressed by this project is that

Pb-free coatings of nearly pure tin tend to grow

“whiskers” which can cause catastrophic shorts

across component leads.

Maureen E. Williams, Christian Johnson,

and Kil-Won Moon

Development of Pb-free surface finishes is

essential for the current move toward Pb-free

microelectronics assembly, and tests which ascertain

the tendency to form “tin whiskers” are in demand.

NIST is providing leadership in two National

Electronics Manufacturing Initiative (NEMI) whisker

projects: identifying fundamental growth mechanisms

and developing an accelerated test. Our goal at NIST

is to provide an understanding of the fundamentals of

the whisker formation, which will ensure that the test

developed by the NEMI group will have widespread

and general applicability.

Filamentary Sn whiskers (typically 1 μm diameter

and several mm long) can grow from a Sn-based

surface finish and cause electrical shorts and failure.

Historically, Pb was added to Sn plate to prevent

whisker growth as well as to lower cost. The current

research program has focused on measuring effects

of alloying additions on whisker formation in Pb-free

Sn-rich deposits. The Sn-Cu system was chosen since

Sn-Ag-Cu is the Pb-free solder of choice for industrial

application. The goal is to substitute a different solute

for Pb in the Sn-rich deposit in order to retard

whisker growth.

Residual stress is generally believed to drive whisker

growth in electroplated Sn. However, the origin of this

stress has not been determined definitively. Our analysis

of pure Sn and Sn-Cu deposits, combining a cantilever

beam method for stress analysis with electron microscopy,

indicates that Cu6Sn5 intermetallic particles in the Sn grains

and along the grain boundaries of Sn-Cu deposits inhibit

stress relaxation (Figure 1). Coarse intermetallic particles

decorate grain boundaries with finer particles within the

grains. The compressive stress in the pure Sn deposit

decreased from an initial level of 14 MPa to zero after

four days. In contrast, the initial compressive stress in

the Sn-Cu deposit was 32 MPa and after twenty-three

Figure 1: (a) Polished section of pure Sn on Cu substrate;

(b) Polished section of SnCu alloy on Cu substrate; (c,d) TEM photos

of intermetallic particles on grain boundaries and in Sn grains.

Figure 2: Calculated stress levels from cantilever beam

measurements of pure Sn and Sn-Cu electrodeposits.

days was still 21 MPa (Figure 2). Whiskers were present

on the Sn-Cu sample after only four days, but after

600 days, the pure Sn sample was still whisker-free. Since

copper is a frequent impurity in electrodeposited Sn,

unintendedly high, undocumented copper concentrations

in commercial Sn deposits may have confounded

controlled variables in previous studies. These results

have been disseminated to the microelectronics community

through NEMI meetings, including the March 2003

NEMI–NIST–TMS Workshop described in the

Technical Highlights section.

Contributors and Collaborators

W.J. Boettinger, L. Bendersky, G.R. Stafford

(Metallurgy Division, NIST); G. Galyon, N. Vo (NEMI

project leaders)

Materials for Micro- and Opto-Electronics
44

Lead-Free Solders and Solderability

In 2003, we have also served as an information

resource to the microelectronics industry on issues

related to the effects of alloy composition, reflow

temperature, and furnace profiles for best melting and

solidification behavior of solders when circuit boards

are assembled, and to the effects of Pb contamination

on alloy melting and assembly reliability.

Figure 1: “NIST

Recommended Practice

Guide on Test Procedures

for Developing Solder Data.”

“The NIST group performed a significant service to

industry by being the focal point for development of a

reliable technology base to support the choice of a new

lead-free alloy. They also led the way for further work

on issues such as tin whiskers, which emerged from

the initial lead-free work. NIST provided not only a

strong technical basis but, by verifying reliability and

comparing alternatives, enabled industry to choose an

alloy based on extensive investigation. The prompt

global establishment of a preferred alloy solution

was critical for Motorola to be an early adopter of

the technology.”

Dr. Robert C. Pfahl, Jr., Director

International and Environmental R&D

Motorola, (retired)

Contributors and Collaborators

W.J. Boettinger, K.-W. Moon, L.E. Smith,

S.W. Claggett, M.E. Williams (Metallurgy Division,

NIST); T. Siewert, C. McCowan (Material Reliability

Division, NIST); J.P. Clech (EPSI, Inc.); J. Bath

(Solectron); R. Gedney (NEMI); E. Bradley (Motorola);

J.E. Sohn (NEMI, formerly Lucent); P. Snugovsky

(Celestica); E. Benedetto (HP); R. Charbonneau

(StorageTek)

Materials for Micro- and Opto-Electronics

Solders and solderability are increasingly tenuous

links in the assembly of microelectronics as a

consequence of ever-shrinking chip and package

dimensions and the international movement

toward environmentally friendly lead-free solders.

In collaboration with the NEMI Pb-Free Assembly

Project, we are providing the microelectronics

industry with measurement tools, data, and

analyses that address national needs in the

implementation of lead-free solders.

Ursula Kattner and Carol Handwerker

Since 1999, NIST has served a major role in the

 National Electronics Manufacturing Initiative

(NEMI) Pb-Free Assembly Project to identify and

move Pb-free solders into the microelectronics industry.

(NEMI is an industry-led consortium of 65 manufacturers,

suppliers, and related organizations brought together to

facilitate leadership of the North American electronics

manufacturing supply chain.) This move toward

Pb-free solders is a direct result of the European

Union ban, starting in 2006, on Pb-containing solders

in electronic products.

 The NEMI Lead-free Task Force and NIST have

worked together to respond to the identified needs by:

■ Identifying and providing the most important

lead-free solder data for the microelectronics

community, including the definitive database on

thermodynamic properties of Pb-free alloys, and

dessiminating such data on the NIST website.

(See “Informatics and Visualization in Materials

Data Delivery” in this volume.) This database allows

the calculation of phase transformations in solder

alloys containing Ag, Cu, Bi, In, Pb, Sb, and Sn, with

additional data for Ag, Cu, and Sn with Ni, which is

used in characterizing interactions between Pb-free

solders and Ni-based surface finishes.

■ Developing and widely disseminating “Recommended

Practice Guide on Test Procedures for Developing

Solder Data.” (See Figure 1.)

■ Providing a list of literature references on alloys,

processing, reliability, environmental issues, and

components for the implementation of lead-free

solders.

■ Completing the microstructure-based failure

analysis on all thermally cycled assemblies as part

of the NEMI’s project’s full-scale reliability trials.

■ Providing chapters on the materials science of

Pb-free solder alloys for three books on Pb-free

solders.
45

Magnetic Properties and Standard Reference Materials

Users of magnetic materials, including the

recording industry, the permanent magnet industry,

and the manufacturers of electric motors and

transformers of all types, need standard reference

materials (SRM’s) to calibrate instruments used to

measure the critical magnetic properties of their

starting materials. The Magnetic Materials Group

develops such standards. We also investigate

methods for improving the efficiency and accuracy

of measuring and characterizing magnetic

materials of industrial interest.

Robert D. Shull and Robert D. McMichael

I

n collaboration with scientists from universities,

 industry, and other Divisions at NIST, this project

prepares magnetic materials that are important to the

scientific and industrial communities and develops

methods for the improved measurement of their

properties. We develop models of hysteresis and

magnetic time dependence that serve as a theoretical

foundation for metrology of accommodation and

aftereffect in magnetic recording and permanent

magnetic materials. We also develop models for

determination of the most efficient methods to fully

characterize the hysteresis and magnetostriction in

magnetic materials.

We develop and produce Standard Reference

Materials for the calibration of existing and planned

instruments used in the measurement of magnetic

properties using the absolute magnetometer developed

in our laboratory (e.g., Figure 1). This year we have

issued garnet magnetic moment SRM’s useful for

calibrating the most sensitive scales in SQUID and

vibrating sample magnetometers. These SRM’s

provide, for the first time, a means for calibrating the

measurements from high sensitivity alternating gradient

magnetometers on an absolute basis. These small

(1 mm diameter) single-crystal yttrium iron garnet

spheres with a nominal mass of about 2.8 mg were

measured using the Faraday technique after calibrating

the magnetometer using the Thorpe–Sentfle method.

Current work includes certifying platinum cylinders as

paramagnetic susceptibility standards for the magnetics

community. This standard reference material will be

useful for calibrating magnetometers where an outside

source of magnetic flux is undesirable. It will also be

useful for determining the true zero field and zero

moment values in magnetometers.

In order to inform the magnetics community of the

availability of these recently prepared magnetic standard

reference materials, a NIST booth on this topic was

organized and manned at the last Magnetism and

Magnetic Materials Conference (MMM, the big annual

conference on magnetism in the U.S.). In addition,

a brochure was assembled in collaboration with the

Measurement Sciences Division of NIST, shown in

Figure 2, and mailed to over 7,000 magneticians, with

an electronic version sent by email to the participants

of the above MMM conference.

Contributors and Collaborators

L.J. Swartzendruber (Magnetronix, Inc.);

D. Twisselmann (Arete Associates, Inc.); D.Mathews,

R. Drew (Metallurgy Division, NIST); S.D. Leigh

(Statistical Engineering Division, NIST); D. Decker

(Measurement Services Division, NIST); L. Bennett,

E. Della Torre (George Washington University)

Figure 1: Pt cylinder, YIG sphere, Ni sphere, and Ni disc SRMs.

Figure 2: Magnetic SRM brochure.

Materials for Micro- and Opto-Electronics
46

Materials for Micro- and Opto-Electronics

Magnetic Properties of Nanostructured Materials

In the past 10 to 15 years, there has been a

remarkable improvement in the technology for

materials preparation, resulting in today’s

capability of controlling morphology and features

at the nanometer level. In magnetic materials,

such control allows the fabrication of nm-thick

(or separated) composite materials of dissimilar

magnetism, leading to materials with novel

magnetic character and unusual property

combinations. We provide the understanding

and metrology that allows U.S. industry to take

advantage of these new materials.

Alexander J. Shapiro and Robert D. Shull

Present day high-density data storage is possible

due to the giant magnetoresistance (GMR) spin

valve, which is now used as the read head in magnetic

disc drives. This structure is composed of two

ferromagnetic (FM) layers separated by a thin

non-magnetic layer. When an external magnetic field

reverses the magnetization of one of the FM layers, the

resistance of the composite changes. Consequently,

one FM layer must maintain a constant magnetization

during this process, usually accomplished by placing

an antiferromagnetic (AF) layer adjacent to it so as

to “exchange-bias” that FM layer. This results in a

hysteresis loop that is shifted along the field axis

as shown in Figure 1(a). Unfortunately, this

exchange-biasing is not well understood.

Neel temperature of the AF but below the Curie point

of the FM (Figure 1b). Application of the alternating

field at elevated temperatures formed a demagnetized

FM composed of striped domains with alternating

magnetization vectors, shown in Figures 1(b) and 2(a),

on top of coincident AF domains. When a field was

applied to this bilayer to saturate the FM [Figures 2(c),

(f)], there still remained a remnant image of the original

domain pattern (Figure 2a), indicating the AF wall

below the FM has not moved.

Figure 1: Hysteresis loops for a NiFe /FeMn bilayer cooled

under (a) constant and (b) alternating field conditions.

Several years ago, we found we could elucidate

some of the basics of the magnetization reversal

process in such systems [V.I. Nikitenko, et. al., PRB

57, R8111 (1998)] by using the magneto-optic indicator

film technique (MOIF) developed in our laboratory.

This domain imaging technique enabled us to show

for the first time that, contrary to popular thought, the

two sides of the hysteresis loop are not symmetrical

but are each governed by different mechanisms. This

year, we have answered another key question regarding

exchanged bias systems: do the domain walls in the AF

move when the FM reverses its magnetization? MOIF

observations were made of a NiFe (FM)/ FeMn (AF)

bilayer which had been ac-demagnetized above the

Figure 2: MOIF images of domains in the FM at the conditions

specified by the positions designated in Figure 1(b).

Some AF spins in the region of the AF/FM interface,

however, are changing during the FM reversal, as

attested to by the fact that Figures 2(e) and (g) only

show domain activity in the same areas for both field

application and removal respectively, contrary to that

for a normal ferromagnet. Similar observations have

also been made on a different AF/FM bilayer, FeMn/

Fe76Mn6C18, wherein the initial coincident domain

structure in the FM and AF was created by elevated

temperature preparation under a low applied field.

As a result of these measurements, theoretical

models may now be improved, and industry should

now be able to better tailor spin valve processing to

obtain improved reproducibility. In the past year,

over 40 % of all papers on exchange-biasing have

referenced our MOIF results.

Contributors and Collaborators

V. Nikitenko, V. Gornakov (Russian Academy

of Sciences); C.L. Chien (Johns Hopkins University);

H.-W. Zhao (Chinese Academy of Sciences)
47

Materials for Micro- and Opto-Electronics

Nanomagnetodynamics

This project provides the magnetic information

storage industry with metrology for magnetization

damping and magnetic inhomogeneity in thin film

ferromagnets. Damping is expected to become a

critical issue for magnetic information storage at

GHz data rates, and inhomogeneity on the scale

of 10 nm in recording media is important for

increased storage density in the new generation

of disk drives, which will use perpendicular

magnetic recording.

Robert D. McMichael

The central issue in interpretation of ferromagnetic

resonance line width data is the determination of

how much of the ferromagnetic resonance line width is

due to damping and how much is due to inhomogeneity.

Ferromagnetic resonance is observed as a peak in

the transverse susceptibility that occurs when the

frequency of the driving field is close to the frequency

of precession. The peak position can be used to

determine sample average properties, but the width

of the resonance peak, or “line width,” is a combined

effect of damping and inhomogeneity.

Existing simple models describe the contribution of

damping to the line width. We have provided reliable

models of inhomogeneity that are key to interpretation

of line width data. These models describe the line

width behavior as a function of frequency and applied

field orientation for different types of inhomogeneity.

 Neglecting the exchange and dipolar interactions

that are characteristic of ferromagnets, local variations

in magnetic properties would be expected to result

in a distribution of local precession frequencies and a

broadened resonance peak. However, interactions tend

to synchronize the precession in neighboring regions,

effectively “smoothing” the inhomogeneity, and

reducing its effect on the line width.

Significant accomplishments in FY03 include:

■ Development of a unified model of inhomogeneous

line broadening in thin films. This model covers

the full range of inhomogeneity and interaction

strengths but is computationally too expensive to use

for fitting. This model established that the transition

from local to collective behavior is governed by

the relative magnitudes of the inhomogeneity and

the region-to-region coupling. See R.D. McMichael,

D.J. Twisselmann, and Andrew Kunz, Phys. Rev.

Lett., 90, Art. No. 277601 (2003).

■ An approximation to the full calculation of

inhomogeneous line broadening using the “two

magnon” model in the strong coupling/weak

inhomogeneity limit and local resonances in the

weak coupling/strong inhomogeneity limit.

■ Useful analytical approximations for the “two

magnon” model for ultra thin films in the limit of

zero damping.

■ Measurement of the damping properties of Cr

in proximity to Permalloy (Figure 1). These

experiments imply that ferromagnetic resonance

measurements in CoCr based hard drive recording

media will not be hindered by excessive damping.

■ Modeling of ferromagnetic resonance line widths in

perpendicular recording media under development

in industry.

Contributors and Collaborators

D.J. Twisselmann, W.F. Egelhoff, Jr., A.P. Chen

(Metallurgy Division, NIST); Andrew Kunz (Lawrence

University); H. Nakamura, M.E. McHenry (CMU);

S. Rezende (Recife, Brazil); G.S.D. Beach,

A.E. Berkowitz (UCSD)

Figure 1: Ferromagnetic resonance linewidth for a

Cr/Permalloy/Cr trilayer as a function of applied field angle.

This plot illustrates the ability to separate the linewidth into a

damping component (pink line) and an inhomogeneous component

(blue line) corresponding to 7 % variations in the effective

magnetization.
48

Materials for Micro- and Opto-Electronics

Anomalously Large Low Temperature Intermixing in

Metallic Thin Films

The objective of this program is to provide

assistance to U.S. companies in the ultra-high

density data storage industry, which includes such

products as hard disk drives and magneto-resistive

random access memory chips. Our work provides

U.S. companies with significant competitive help

by investigating the scientific issues underlying

the manufacturing process. Often, this scientific

understanding will point the way to improved

manufacturing processes.

William F. Egelhoff, Jr.

As the scale of microelectronic devices shrinks,

 surfaces and interfaces play increasingly important

roles as they become a larger fraction of the total

device volume. Interfaces are especially important

for the metallic thin films so common in layered device

structures. Interfaces between thin films may appear

to be abrupt at macroscopic length scales but diffuse

at atomic length scales. Fortunately, when metallic thin

films are deposited on one another at room temperature,

there is generally little intermixing at the interface.

Typically, if there is any intermixing, it is limited to one

or two atomic layers. However, recent collaborative

studies by NIST and the University of Durham have

shown that such low-temperature intermixing can be

far more extensive when Al and a transition metal (TM)

are involved.

Thin film samples of the type “Al on TM” and

“TM on Al” were prepared at the NIST Magnetic

Engineering Research Facility and analyzed by

grazing-incidence x-ray reflectometry (GIXR)

at Durham. GIXR is an ideal technique for these

studies since it is extremely sensitive to intermixing

at interfaces. We find the intermixing profile

perpendicular to the interface is usually well described

by a Gaussian distribution, as expected, since diffusion

processes often follow Fick’s Law. The results are

displayed in Table 1 as the full-width-at-half-maximum

(FWHM) of the intermixed region. The FWHM results

span the range from 0.1 nm for Al on W to 16.8 nm

for Cu on Al. This Cu-on-Al result corresponds to

approximately 100 atomic layers of intermixing.

Such results are a great surprise to researchers in

the field. For example, electronic properties for a thin

film structure consisting of 2 nm Cu /1 nm Al/2 nm Cu

were recently reported and analyzed as if the interfaces

were atomically sharp. In fact, the sample must have

been essentially a random alloy!

Among other combinations showing large

intermixing were Mn on Al with 15.1 nm and V on Al

with 9.4 nm. These surprising results suggest that the

heat of alloying is driving much more extensive chemical

reactions at the interface than had heretofore been

known. These results have important implications for

many microelectronic devices incorporating Al films.

For example, problems in magnetic-tunnel-junction

devices may be directly attributed to such phenomena.

NIST is also developing solutions to such problems

based on oxide barriers to suppress the intermixing.

Table 1: The intermixing FWHM (in nanometers)

for thin films of Al on transition metals and

transition metals on Al

TM Element Al on TM TM on Al

Ti 1.7 5.0

V 2.6 9.4

Cr 0.5 3.3

Mn 10.4 15.1

Fe 0.9 2.1

Co 0.8 6.8

Ni 1.4 7.9

Cu 2.8 16.8

Zr 1.0 5.1

Nb 0.8 3.6

Mo 1.3 3.4

Ru 0.8 5.2

Rh 0.4 4.7

Pd 4.8 5.6

Ag 2.5 4.5

Hf 2.0 4.4

Ta 0.1 0.9

W 0.1 3.5

Re 2.1 8.6

Os 0.1 7.1

Ir 0.2 5.4

Pt 1.9 4.5

Au 5.2 6.3

Contributors and Collaborators

R.D. McMichael (Metallurgy Division, NIST);

M.D. Stiles (Electron and Optical Physics Division, NIST);

C.J. Powell (Surface and Microanalysis Science Division,

NIST); Readrite Corporation; Seagate Corporation;

J.D.R. Buchanan (Durham, UK); J. Moodera (MIT)
49

Program Overview

Materials Property Measurements

This program responds both to the Materials

Science and Engineering Laboratory (MSEL) customer

requests and to the Department of Commerce 2005

Strategic Goal of “providing the information and

framework to enable the economy to operate efficiently

and equitably.” For example, manufacturers and their

suppliers need to agree on how material properties

should be measured. Equally important, engineering

design depends on accurate property data for the

materials that are used.

The MSEL Materials Property Measurement

Program works toward solutions to measurement

problems on scales ranging from the macro to

the nano, in four of the Laboratory’s Divisions

(Ceramics, Materials Reliability, Metallurgy, and

Polymers). The scope of its activities ranges from

the development and innovative use of state-of-the-art

measurement systems, to leadership in the development

of standardized test procedures and traceability

protocols, to the development and certification of

Standard Reference Materials (SRMs). A wide range

of materials is being studied, including polymers,

ceramics, metals, and thin films (whose physical

and mechanical properties differ widely from the

handbook values for their bulk properties).

Projects are directed toward innovative new

measurement techniques. These include:

■ Measurement of the elastic, electric, magnetic, and

thermal properties of thin films and nanostructures

(Materials Reliability Division);

■ Alternative strength test methods for ceramics,

including cylindrical flexure strength and diametral

compression (Ceramics Division); and

The MSEL Materials Property Measurement

Program is also contributing to the development of

test method standards through committee leadership

roles in standards development organizations such as

the American Society for Testing of Materials (ASTM)

and the International Standards Organization (ISO).

In many cases, industry also depends on measurements

that can be traced to NIST Standard Reference Materials

(SRMs). This program generates the following SRMs

for several quite different types of measurements:

■ Charpy impact machine verification (Materials

Reliability Division);

■ Hardness standardization of metallic materials

(Metallurgy Division); and

■ Hardness standardization and fracture toughness

of ceramic materials (Ceramics Division).

Supporting the Materials Property Measurements

Program is a modeling and simulation effort to connect

microstructure with properties. The Object-Oriented

Finite-Element (OOF) software developed at NIST is

being used widely in diverse communities for material

microstructural design and property analysis at the

microstructural level.

In addition to the activities above, all four

divisions provide assistance to various government

agencies on homeland security and infrastructure

issues. Projects include assessing the performance

of structural steels as part of the NIST World

Trade Center Investigation, advising the Bureau of

Reclamation on metallurgical issues involving pipelines

and dams, advising the Department of the Interior

on the structural integrity of the U.S.S. Arizona

Memorial, advising the U.S. Customs Service on

materials specifications for ceramics, and advising

the Architect of the Capitol on repair procedures for

cracks in the outer skin of the Capitol Dome.

Contact: Sam R. Low
50

Analysis of Structural Steel in the World Trade Center

In 2002, NIST became the lead agency in a

planned investigation of the World Trade Center

collapse. The investigation addresses many

aspects of the catastrophe, from occupant egress

to factors affecting how long the Twin Towers

stood after being hit by the airplanes, with a goal

of gaining valuable information for the future.

A critical aspect of the investigation is the

metallurgical and mechanical analysis of

structural steels from the Twin Towers.

The analysis includes characterization of

properties, failure modes, and temperature

excursions seen by the steel.

Steve W. Banovic, William E. Luecke,

Tim Foecke, Richard J. Fields, and Frank W. Gayle

NIST has prepared a technical plan to address these

issues (see http://wtc.nist.gov/). A primary objective

of the investigation is to determine why and how the

towers collapsed after the initial impact of the aircraft.

As part of this investigation, the Metallurgy and

Materials Reliability Divisions in MSEL are studying

recovered structural steel pieces from the WTC site.

Progress in this study is outlined here.

Task 1 — Collect and catalog physical evidence.

More than 200 pieces of the World Trade Center

towers have been collected and brought to NIST. The

locations of 41 exterior column panels within the WTC

towers have been positively identified, of which 15

were located in or near the impact zones of the aircraft.

Specified strengths of structural components have been

identified through engineering drawings for the buildings.

Task 2 — Categorize failure mechanisms based on

visual evidence. Recovered steel is being examined and

documented as to failure mechanisms (Figure 1).

Task 3 — Determine steel properties to support

structure performance and airplane impact modeling

studies. Fourteen grades of steel were specified in the

WTC towers. All grades have been characterized for

room temperature mechanical properties, and initial

high-temperature test results are complete. High strain

rate testing is underway to determine the effects of strain

rate on the strength of key structural elements. Chemical

composition and metallographic examinations have

been completed on the majority of the steels. Creep,

or time-temperature-dependent behavior, will be studied

after the high-temperature properties are developed.

Task 4 — Correlate determined steel properties with

specified properties. As data are generated during the

testing phase of the investigation, measured values of

strength are compared to those specified in the

engineering drawings.

Task 5 — Analyze steel to estimate temperature

extremes. Microscopic, macroscopic and metallographic

analyses are under way to determine the maximum

temperature excursions seen by the steel.

An interim report, containing data generated to date,

will be released to aid in the modeling of the aircraft

impact and building response to subsequent fires.

A final report will be complete at the end of FY04.

Contributors and Collaborators

D. McColskey, T. Siewert, R. Santoyo, L. Rodine

(Materials Reliability Division, NIST)

Figure 1: Failure mechanisms observed in recovered WTC

steel will be used to gain insight into the building collapse.

Materials Property Measurements

The collapse of the twin World Trade Center

(WTC) Towers on September 11, 2001, was the

worst building disaster in human history. Engineers,

emergency responders, and the nation were largely

unprepared for such a catastrophe. These events

highlight the following national needs:

■ To establish the probable technical causes of the

collapses and derive the lessons to be learned;

■ To develop and disseminate immediate guidance and

tools to assess and reduce future vulnerabilities; and

■ To produce the technical basis upon which

cost-effective changes to national practices and

standards can be developed.
51

Hardness Standardization: Rockwell, Vickers, Knoop

Hardness is the primary test measurement used to

determine and specify the mechanical properties

of metal products. The Metallurgy Division is

engaged in all levels of standards activities to

assist U.S. industry in making hardness measurements

compatible with other countries around the world.

These activities include the standardization of the

national hardness scales, development of primary

reference transfer standards, leadership in national

and international standards writing organizations,

and interactions and comparisons with various U.S.

laboratories and the National Metrology Institutes

of other countries.

Sam R. Low and Christian E. Johnson

At the international level, we are leading the Working

 Group on Hardness (WGH) under the International

Committee for Weights and Measures (CIPM). The

primary goal is to standardize hardness measurements

worldwide. As secretary of the WGH, we have lead

an effort this year to better define the Rockwell

hardness test procedure used by National Metrology

Institutes (NMIs). Also, NIST’s capabilities for

hardness calibrations have recently been accepted into

the CIPM Mutual Recognition Arrangement (MRA),

an international document providing a means for

comparing the measurements and calibrations of the

world’s NMIs. Other activities include heading the

U.S. delegation to the ISO committee on hardness

testing of metals, which oversees the development

of the ISO hardness test method standards and is the

Secretariat for the International Organization of Legal

Metrology (OIML) committee on hardness, and we

have proposed a revision of international requirements

for regulating Rockwell hardness machines.

Our primary task at the national level is to standardize

the U.S. national hardness scales and to provide a means

of transferring these scale values to industry. Currently,

we are producing test block Standard Reference

Materials® (SRMs) for the Rockwell, Vickers and Knoop

hardness scales, as well as developing new reference

standards. Twelve microhardness SRMs for Vickers and

Knoop hardness are now available, including two new

nickel Vickers SRMs. Using electrodeposition technology,

the standards are produced with uniform properties

and microstructure. One hundred thirty-five SRMs

were produced and certified to fill out-of-stock inventory.

Work on a prototype high hardness Vickers microhardness

SRM (≈ 800) was redirected from an electrodeposited

amorphous material to an evaluation of uniformity in

microhardness values for Rockwell 63 HRC SRM test

blocks at a load of 4.9 N (500 gf).

We also completed the calibration of two new SRMs

for the Rockwell B scale (HRB) to complement the

three SRM Rockwell C scale blocks currently available.

The HRB scale is used for testing softer metals, such

as aluminum, copper and brass. Work is also being

planned to produce a new Rockwell diamond indenter

SRM, which has become feasible due to the successful

completion of a Small Business Innovative Research

(SBIR) Phase-2 project with Gilmore Diamond Tools

to develop an improved method for manufacturing

geometrically correct Rockwell diamond indenters.

Contributors and Collaborators

J. Fink, D. Kelley, L. Ma, H. Gates (Metallurgy

Division, NIST); J. Song, C. Evans, R. Clary (Fabrication

Technology Division, NIST); W. Liggett, Jr., N. Zhang

(Statistical Engineering Division, NIST); S. Doty, B. Belzer,

D. Faison (Standards Services Division, NIST);

B. MacDonald (Measurement Services Division, NIST);

W. Stiefel (Weights and Measures Division, NIST);

M. Mihalec (Gilmore Diamond Tools, Providence, RI)

Figure 1: Model of stresses and material deformation

occurring during Rockwell hardness ball indentation.

Other activities at the national level included:

the assessment of commercial secondary hardness

calibration laboratories for the NIST National

Voluntary Laboratory Accreditation Program (NVLAP)

providing direct linkage to the use of the NIST SRMs;

development of a new method for estimating hardness

uncertainty that has been accepted for inclusion into

the ASTM-International Rockwell hardness test method

standard E18; and development of indentation software

models (Figure 1) that have been used to estimate

the effect of varying test parameters on the resulting

hardness value.

Materials Property Measurements
52

Marine Forensics and Preservation of Historic Shipwrecks

Historic shipwrecks are valuable cultural

resources continuously under attack by their

environment. Preservation techniques aimed at

slowing corrosion processes and mechanically

stabilizing shipwreck structures are being modeled

and designed in coordination with the National

Park Service, NOAA, and the U.S. Navy. These

techniques are being applied to such wreck sites

as the USS Arizona, the Ellis Island Ferry, RMS

Titanic, CSS Hunley, and USS Monitor.

Tim Foecke

Since sinking at Pearl Harbor on December 7, 1941,

 the wreck of the USS Arizona has been slowly

corroding and collapsing (Figure 1). The monument

that straddles the wreck sees over 700,000 visitors per

year, and there is immense interest in preserving the

wreck for as long as possible. Aside from the historical

interest, there are environmental risks associated with

any large-scale collapse of the wreck as there is still an

estimated 2,000 m3 (500,000 gal) of fuel oil trapped

below water.

wreck and how these stresses will build toward a

critical state as the wreck continues to corrode. Using

this model, various preservation techniques such as

cathodic protection and physical reinforcements will be

tried in the computer before anything is implemented on

the wreck.

Figure 1: Current state of the USS Arizona in Pearl Harbor

(from NPS Submerged Cultural Resources Unit).

Figure 2: Ellis Island Ferry.

The Submerged Cultural Resources Unit (SCRU)

of the National Park Service has responsibility for

maintaining and preserving the wreck and approached

the Metallurgy Division for assistance, knowing their

past experience in marine forensics. Assistance is being

provided in several areas. Advice is being given on

methods to be employed to measure the remaining

thickness of the hull through the bioencrustation, and

characterization of the steel and the encrustation layer

is being performed.

This information is being input, along with the

physical survey of the wreck, into a finite element

model that will be used to predict the stresses in the

In a preliminary project, a smaller simulation has

been completed of the Ellis Island Ferry (Figure 2),

which carried immigrants to Manhattan from 1901 to

1953, and sank at her moorings in 1968 at Ellis Island.

The SCRU wanted information about the stability of the

wreck under several salvage scenarios. They used this

information to recommend to the National Park Service

not to raise the wreck. This project allowed NIST to work

out the details of water and mud loadings on submerged

hulls, which will be used in the model of the Arizona.

The tools developed in this project will be

transferred to companies and organizations that

are responsible for monitoring submerged wrecks

containing hazardous materials, allowing them to

better simulate critical conditions.

In addition to these two ships, we are providing

assistance and technical expertise to NPS, NOAA, and

the Navy regarding preservation of the CSS Hunley

(on shore in Charleston, SC), the USS Monitor

(partially salvaged), and NOAA’s monitoring and

scientific surveys of the wreck of the RMS

Titanic, building on past work on this ship.

Contributors and Collaborators

L. Ma (Metallurgy Division, NIST); L. Murphy,

M. Russell, D. Conlin (Submerged Cultural Resources

Unit, National Park Service); Lt. J. Weirich (NOAA);

Cdr. J. Morganthou (CINCPAC, U.S. Navy)

Materials Property Measurements
53

Materials Structure Characterization

Fundamental to the field of materials science and

engineering is the study of the relationships between

processing, structure, properties, and performance

of materials. Therefore, tools and techniques for

the characterization of materials structure is a

cornerstone of the field. The NIST Materials Science

and Engineering Laboratory (MSEL) has a long tradition

of supporting and developing measurement methods

and facilities for materials structure characterization.

Facilities within MSEL include optical and electron

microscopy, optical and electron scattering and

diffraction, a state-of-the-art x-ray diffractometer, the

NIST Center for Neutron Research, and experimental

stations at the National Synchrotron Light Source

(NSLS) at Brookhaven Laboratory and at the Advanced

Photon Source (APS) at Argonne National Laboratory.

At the NSLS, NIST operates a soft x-ray station in

partnership with Dow and Brookhaven National

Laboratory. At the APS, NIST is a partner with the

University of Illinois at Urbana/Champaign, Oak Ridge

National Laboratory, and UOP in a collaboration called

UNICAT. At both facilities, NIST scientists and

researchers from industry, universities, and government

laboratories perform state-of-the-art measurements on

a wide range of advanced materials. NIST scientists

have consistently advanced the limits of these facilities

in order to improve spatial resolution and sensitivity

needed, for example, to interrogate the microstructure

of both highly anisotropic and/or gradient materials

such as advanced thermal coatings and fuel cell

systems. Studies currently underway at these facilities

include: in-situ measurements of nanoparticle

production; structure and dispersion of carbon

nanotubes; three-dimensional imaging of natural and

artificial tissues; surface and subsurface damage in

UV lithography optics; strain-induced ferroelectric

transitions in thin films; and determination of molecular

orientation and bond concentration on chemically

heterogeneous surfaces.

The materials characterization program has

a strong emphasis on electron microscopy. The MSEL

Electron Microscopy Facility provides structure and

compositional characterization of a wide range of

materials. The facility consists of two transmission

electron microscopes (TEMs), three scanning electron

microscopes (SEMs), a specimen preparation laboratory,

and an image analysis/computational laboratory.

The JEM3010 TEM resolves the atomic structure and

employs an energy selecting imaging filter and x-ray

detector (EDS) for analytical characterization of thin

foil specimens. The JSM6400 SEM employs electron

backscattered diffraction /phase identification and EDS

systems to characterize the texture and composition

of materials. Highlights from the facility for FY2003

include: the computer domain is now active, providing

streamlined user access and network file storage;

a research collaboration with the NIST Semiconductor

Electronics Division is underway to characterize

quantum effects in confined Si devices; the size and

shape of III–V quantum dots are characterized with

the NIST Optoelectronics Division; and composition

maps of electrodeposited nanowires with tunable

magnetic properties are generated in collaboration

with Johns Hopkins University.

This MSEL program also incorporates standards

activities. A state-of-the-art x-ray diffractometer has

been developed to study the metrology of powder

diffraction in order to develop the next generation of

diffraction standard reference materials. A variety of

standard reference materials (SRMs) needed by the

U.S. polymers industry, research laboratories, and

other federal agencies have recently been developed:

polyethylene of narrow mass distribution; nonlinear

fluids for rheological measurements; melt flow

standards; and the first reference biomaterial, an

orthopedic grade ultra-high molecular weight

polyethylene.

Recent program activities utilize matrix-assisted laser

desorption/ionization time-of-flight mass spectrometry

(MS) to address the need for improved characterization

of the molecular structure of polyolefins, a dominant

commercial polymer. This work has extended the

upper mass limit detectable by MS to 15,000 g/mol

and, by observing individual oligomeric species by

mass, has revealed details of the molecular structure.

A major cross-cutting activity within this program

is the multi-scale, multi-modal imaging and visualization

project. The goal of this project is to combine disparate

sets of 3-D imaging data that contain complementary

information on overlapping length scales to produce

an interactive visualization scheme for multivariate

data sets. This year focused on further improvements

and additions to the suite of imaging tools for tissue

engineering metrology. Osteoblasts cultured in a

poly (ε-caprolactone) scaffold have been imaged,

demonstrating the advantages of optical coherence

and confocal fluorescence microscopies over

conventional laser scanning confocal microscopy.

This instrument was upgraded by completely rebuilding

the image acquisition software, hardware, and optical

train. These improvements enabled an increase in

image acquisition speed (2X) and accuracy

(from 5 μm to 360 nm).

Contact: John E. Bonevich

Program Overview
54

Materials Structure Characterization

Nanoscale Characterization by Electron Microscopy

Electron microscopy is used to characterize the

structure and composition of materials at the

nanometer scale to better understand and improve

their properties. New measurement techniques

in electron microscopy are being developed

and applied to materials science research.

The MSEL Electron Microscopy Facility serves

the Metallurgy, Ceramics, and Polymers Divisions

as well as other NIST staff and outside

collaborative research efforts.

John E. Bonevich

Atomic-scale structure and compositional

characterization of materials can lend crucial insights

to the control of their properties. For instance, direct

observation of local structures by transmission electron

microscopy (TEM) provides an important information

feedback to the optimization of crystal growth and

processing techniques. Various characteristics may be

observed such as crystal structure and orientation, grain

size and morphology, defects, stacking faults, twins

and grain boundaries, second phase particles — their

structure, composition and internal defect structure,

compositional variations as well as the atomic structure

of surfaces, and interfaces.

The MSEL Electron Microscopy Facility consists

of two transmission electron microscopes, three

scanning electron microscopes, a specimen preparation

laboratory, and an image analysis/computational

laboratory. The JEM3010 TEM resolves the atomic

structure and employs an energy selecting imaging

filter (IF) and x-ray detector (EDS) for analytical

characterization of thin foil specimens. The JSM6400

SEM employs electron backscattered diffraction/phase

identification (EBSD) and EDS systems to characterize

the texture and composition of materials.

Highlights from the EM Facility for FY2003 include:

■ Facilities computer resources have been upgraded,

providing streamlined user access and network file

storage.

■ Collaboration with the Semiconductor Electronics

and Electricity Divisions (EEEL) to characterize

quantum effects in confined Si devices.

■ Characterization of the size and shape of III-V

quantum dots, with the Optoelectronics Division

(EEEL).

■ Compositional mapping of electrodeposited

nanowires with tunable magnetic properties,

fabricated at Johns Hopkins University (Figure 1).

Contributors and Collaborators

D. Josell, T. Moffat, R.D. McMichael

(Metallurgy Division, NIST); A. Roshko, S.Y. Lehman

(Optoelectronics Division, NIST); E. Vogel,

N. Zimmerman (Semiconductor Electronics Division,

NIST); P. Searson (Johns Hopkins University)

Figure 1: Composition maps of Ni/Cu electrodeposited multilayer

nanowires. Modulation of the composition wavelength provides

a means to tune the magnetic properties as desired. The Ni layer

thickness varies from 5 nm (top) to 1 nm (bottom).
55

Materials Structure Characterization

USAXS Imaging: Microscope Development and Validation

Modeling the behavior of complex materials

requires detailed knowledge of the underlying

three-dimensional microstructure. Ultra-smallangle X-ray scattering (USAXS) imaging is a new

class of synchrotron X-ray imaging techniques

that uses USAXS as the contrast mechanism.

The technique provides imaging and statistical

data that cannot be obtained using any other

experimental methods.

Lyle E. Levine, David J. Pitchure, and

Gabrielle G. Long

USAXS imaging was developed by NIST

 researchers and was first demonstrated in

May 2000. The primary advantages over existing X-ray

imaging techniques are its inherently higher contrast

and its USAXS-derived ability to provide quantitative

data on object shapes and size distributions. USAXS

imaging has broad applicability to a wide range of

material systems including metals, ceramics, polymers,

and biological materials. Over the past year, work

has concentrated on two main areas. First, major

improvements in the instrumentation have greatly improved

the imaging capabilities, and second, a wide range

of material systems have been explored to determine

where USAXS imaging can have the greatest impact.

The USAXS imaging experiments are conducted

on the UNICAT sector 33 insertion-device beamline

at Argonne National Laboratory’s Advanced Photon

Source. A high-intensity, parallel, monochromatic

X-ray beam passes through entrance slits that define

the size, shape and position of the beam. Imperfections

in the X-ray beam are removed using multiple Bragg

reflections within a <111> channel-cut Si crystal

referred to as the collimator. Within the sample,

local density variations from the microstructure

produce X-ray scattering at small angles. The X-rays

leaving the sample are then angle-filtered using another

pair of <111> Si crystals referred to as the analyzer.

The only X-rays from the sample that can pass through

the analyzer are those scattered by the microstructure

at a specific angle. This angle can be selected by

rotating the analyzer. Images are then formed

by either exposing nuclear emulsion plates or using

an X-ray camera system.

During the past year, several major improvements

have been made in the instrumentation. These

include new analyzer crystals whose surfaces were

chemically polished to minimize image aberrations,

a multiple-sample motorized rotation stage for doing

stereo imaging and a motorized rotating goniometer

stage for aligning the samples and then rotating them

over 180° in situ. The most important improvement

in instrumentation was the design, construction, and

testing of a new high-resolution X-ray camera. In this

device, the X-rays hit a single-crystal scintillator that

converts them to visible light. The resulting image is

then magnified using an optical microscope system

using a cooled CCD chip, infinity-focus objective

lenses, an auxiliary lens system to produce a real image

on the CCD plane, and a mirror to shift the optical axis

away from the X-ray beam. The spatial resolution of

the camera is approximately 1 μm. Remote computer

control is available for all operations of the USAXS

imaging equipment, and sequences of images (such as

during sample rotations) can be acquired automatically

using macro programs.

Figure 1: USAXS image of density variations within the

Allende meteorite.

As examples of the technique’s versatility,

USAXS imaging has been successful at imaging creep

cavities and cracks in copper, fatigue-generated voids

in lead-free solder balls in microelectronic devices, silica

beads embedded in polycarbonate and polypropylene,

the Allende meteorite (see Figure 1), indentation crack

surfaces in ceramics, artificial polymer tissue scaffolds,

and fiber structures within bovine and human cartilage.

Contributors and Collaborators

J. Ilavsky (Ceramics Division, NIST); J. Dunkers

(Polymers Division, NIST); P. Jemian (UNICAT);

C. Muehleman (Rush Medical College); Denton Ebel

(American Museum of Natural History)
56
57

Metallurgy Division FY03 Annual Report Publication List

Metallurgy Division FY03 Annual Report Publication List

Microstructural Origins of Surface

Roughening and Strain Localization

Banovic, S.W., and T. Foecke. “Evolution of

strain-induced microstructure and texture in

commercial aluminum sheet under balanced biaxial

stretching.” Metallurgial and Materials Transactions

A, 34A (3), 657–671, 2003.

Banovic, S.W., M.D. Vaudin, T.H. Gnaeupel–Herold,

K.P. Rodbell, and D. Saylor. “Studies of deformation

induced texture development in sheet materials using

diffraction techniques.” Materials Science and

Engineering A, (in press), 2003.

Shim, Y., M.R. Stoudt, L.E. Levine, S.W. Banovic,

and R.J. Fields. “Material model for strain-induced

surface roughening of sheet metal.” Numisheet 2002:

5th International Conference and Workshop on

Numerical Simulation of 3D Sheet Forming Processes.

Ed. D.Y. Yang, et al. Seoul, Korea, pp. 155–160, 2002.

Stoudt, M.R., S.W. Banovic, and T. Quarrick.

“Evolution of deformation induced surface

morphologies developed on Fe-base sheet metals.”

Automotive Sheet Steels. Ed. B.J. Allen.

Warrendale, PA: TMS, 2003.

Stoudt, M.R., and R.E. Ricker. “The influence of

grain size on the roughening behavior of Al–Mg alloys.”

Innovations in Processing and Manufacturing of

Sheet Materials. Ed. M. Demeri. Warrendale, PA:

TMS, pp. 237–244, 2001.

Stoudt, M.R., R.C. Cammarata, and R.E. Ricker.

“Influence of nanometer-scale multilayered thin films

on fatigue crack initiation.” Thin Films — Stresses

and Mechanical Properties VIII. Ed. R. Vinci, et. al.

North Holland, NY: MRS, pp. 15–17, 1999.

Stoudt, M.R. “The influence of surface roughness

on the deforming friction behavior of Al–Mg alloys.”

Aluminum 2002. Ed. M.H. Skillingberg and S.K. Das.

Warrendale, PA: TMS, pp. 27–34, 2002.

Stoudt, M.R., and R.E. Ricker. “The relationship

between grain size and the surface roughening behavior

of Al–Mg alloys.” Metallurgical and Materials

Transactions A, 33A (9), 2883–2889, 2002.

Plasticity, Fabrication Processes,

and Performance

deWit, R. “Determination of the single crystal

elastic constants by diffraction from a cubic

polycrystal.” NISTIR 6944, 2003.

Ma, L., T.F. Zahrah, and R.J. Fields. “Numerical

3D simulation of cold compaction and springback for

particulate reinforced composites.” Powder Metallurgy

Journal, (in press), 2003.

Underlying Processes of Plastic

Deformation in Metal Alloys

Delos–Reyes, M.A., M.E. Kassner, and L.E. Levine.

“X-ray diffraction and the existence of long range

internal stresses.” Proceeding of Plasticity 2003,

(in press), 2003.

Kramer, D.E., M.F. Savage, and L.E. Levine.

“AFM observations of slip band development in Al

single crystals.” Acta Materialia, (submitted), 2003.

Levine, L.E., and R.M. Thomson. “A statistical

connection between dislocations and mechanical

properties.” Dislocations, Plasticity and Metal Forming.

Ed. A. Khan. Fulton: Neat Press, (in press), 2003.

Slutsker, J., and A. Roytburd. “Control of intrinsic

instability of superelastic deformation.” International

Journal of Plasticity, 18, No. 11, 1561–1581, 2002.

Atomization Processing —

Recommended Practices

Biancaniello, F.S., R.D. Jiggetts, M.R. Stoudt,

R.E. Ricker, and S.D. Ridder. “Suitability of powder

processed high nitrogen stainless steel alloys for high

performance applications.” 2002 Advanced in Powder

Metallurgy and Particulate Materials, Part 3 —

Particulate Production, MPIF, 2002.

Mates, S.P., F.S. Biancaniello, and S.D Ridder.

“An alternative view of close-coupled gas atomization

of liquid metals.” 2002 Advances in Powder Metallurgy

and Particulate Materials, Part 3 — Particulate

Production, MPIF, 2002.

Mates, S.P., and G.S. Settles. “A study of liquid

metal atomization using close-coupled nozzles, part 1:

gas dynamics.” Atomization and Sprays, (in press),

2003.

Mates, S.P., and G.S. Settles. “A study of liquid

metal atomization using close-coupled nozzles, part 2:

atomization behavior.” Atomization and Sprays,

(in press), 2003.

Ridder, S.D. “Measurement and control of metal

flow-rate in a gas-metal atomizer.” 2002 Advances in

Powder Metallurgy and Particulate Materials, Part 3 —

Particulate Production, MPIF, 2002.
58

Metallurgy Division FY03 Annual Report Publication List

High Speed Machining

Basak, D., H.W. Yoon, R. Rhorer, T.J. Burns, and

T. Matsumoto. “Temperature control of pulse heated

specimens in a Kolsky bar apparatus using microsecond

time-resolved pyrometry.” International Journal of

Thermophysics, (in press), 2003.

Basak, D., H.W. Yoon, R. Rhorer, and T.J. Burns.

“Microsecond time-resolved pyrometry during rapid

resistive heating of samples in a Kolsky bar apparatus.”

American Institute of Physics, (in press), 2003.

Rhorer, R., L. Levine, T. Burns, R. Fields, H. Yoon,

M. Davies, D. Basak, E. Whitenton, G. Blessing,

B. Dutterer, and M. Kennedy. “Constitutive model data

for machining simulation using the NIST pulse-heated

Kolsky bar.” Dislocations, Plasticity and Metal Forming.

Ed. A.S. Khan. Fulton: Neat Press, pp. 103–105, 2003.

Rhorer, R., D. Basak, G. Blessing, T. Burns,

M. Davies, B. Dutterer, R. Fields, M. Kennedy, L. Levine,

E. Whitenton, and H. Yoon. “Kolsky bar with electrical

pulse heating of the sample.” Proceedings for Society

of Experimental Mechanics Annual Conference,

Session No. 4, Paper No. 119, Society of Experimental

Mechanics, 2003.

Yoon, H.W., D. Basak, R. Rhorer, E. Whitenton,

T. Burns, R. Fields, and L. Levine. “Thermal imaging of

metals in a Kolsky-bar apparatus.” Thermosense XXV.

Eds. E. Cramer and X.P. Maldague. Proceedings of

SPIE, 5073, 284–294, 2003.

Phase Field Modeling of the

Electrochemical Interface

Guyer, J.E., W.J. Boettinger, J.A. Warren,

and G.B. McFadden. “Phase Field Modeling of

Electrochemistry Equilibrium.” Physical Review E,

(submitted), 2003.

Guyer, J.E., W.J. Boettinger, J.A. Warren,

and G.B. McFadden. “Phase Field Modeling of

Electrochemistry: Kinetics.” Physical Review E,

(submitted), 2003.

Combinatorial Methods for Thin Films

Lu, C.J., L.A. Bendersky, K. Chang, and I. Takeuchi.

“HRTEM study on the extended defect structure of

epitaxial Ba0.3Sr0.7TiO3 thin films grown on (001)

LaAl03.” Proceedings of MRS Symposium, (in press),

2003.

Lu, C.J., L.A. Bendersky, K. Chang, and I. Takeuchi.

“High resolution electron microscopy study on the

defect structure and strain relaxation of epitaxial

Ba0.3Sr0.7TiO3 thin films grown on (001) LaA10.”

MRS Proceedings, Vol. 751, Z3.3, 2003.

Lu, C.J., L.A. Bendersky, K. Chang, and I. Takeuchi.

“Dissociation and evolution of threading dislocations

in epitaxial Ba0.3Sr0.7TiO3 thin films grown on (001)

LaAlO3.” Journal of Applied Physics, 93 (1), 1, 2003.

Lu, C.J., L.A. Bendersky, K. Chang, and I. Takeuchi.

“High-resolution identifications of 1⁄2 <110> stacking

faults in epitaxial Ba0.3Sr0.7TiO3 thin films.” Philosophical

Magazine, 83, 1565, 2003.

Phase Diagrams for III–V Thin Films

and Metal Interconnects

Bendersky, L.A., D. Tsvetkov, and Y. Melnik.

“Transmission electron microscopy study of a defected

zone in GaN on a SiC substrate grown by hydride

vapor phase epitaxy.” Journal of Applied Physics, 94,

Issue 3, 1676–1685, 2003.

Davydov, A.V., and U.R. Kattner. “Revised

Thermodynamic description of the Co-Mo system.”

Journal of Phase Equilibria, 24, 209, 2003.

Davydov, A.V., L.A. Bendersky, W.J. Boettinger,

D. Josell, M.D. Vaudin, C.S. Chang, and I. Takeuchi.

“Combinatorial investigation of structural quality of

Au/Ni contacts on GaN.” Applied Surface Science

Journal, (in press), 2003.

Lu, C.J., A. Davydov, D. Josell, and L.A. Bendersky.

“Interfacial reactions of Ti/n-GaN contacts at elevated

temperature.” Journal of Applied Physic, 94, No. 1,

245–253, (in press), 2003.

Lu, C.J., and L.A. Bendersky. “Suppression of

threading dislocations in InN thin films grown on

(0001) sapphire with a GaN buffer layer.” Applied

Physics Letters, (in press), 2003.

Motayed, A., A.V. Davydov, L.A. Bendersky,

M.C. Wood, M.A. Derenge, D.F. Wang, K.A. Jones,

and S.N. Mohammad. “Novel high-transparency Ni/Au

bilayer contacts to n-type GaN. Journal of Applied

Physics, 92, 5218–5227, 2002.

Sanford, N.A., L.H. Robins, A.V. Davydov,

A. Shapiro, A.V. Tsvetkov, A.V. Dmitriev, S. Keller,

U.K. Mishra, and S.P. DenBars. “Measurements of the

refractive indices of MOCVD and HVPE grown AlGaN

films using prism-coupling techniques correlated

with spectroscopic reflection/transmission analysis.”

Materials Research Society Symposium Proceedings,

743, L11.21.1–6, 2003.

Schenck, P., D.L. Kaiser, and A.V. Davydov.

“High-throughput characterization of the optical

properties of compositionally graded combinatorial

films.” Applied Surface Science Journal, (in press),

2003.
59

Metallurgy Division FY03 Annual Report Publication List

Unland, J., B. Onderka, A. Davydov, and

R. Schmid–Fetzer. “Thermodynamics and phase

stability in the Ga-N system.” Journal of Crystal

Growth, 256, 33, 2003.

Informatics and Visualization in

Materials Data Delivery

Davydov, A.V., and U.R. Kattner. “Revised

thermodynamic description of the Co-Mo system.”

Journal of Phase Equilibria, 24, 209, 2003.

Kattner, U.R., J.E. Morral, and W.J. Boettinger.

“Databases for computational thermodynamics and

diffusion modeling.” Journal of Phase Equilibria,

(in press), 2003.

Kattner, U.R., W.J. Boettinger, and J.E. Morral.

“Database for computational thermodynamics and

diffusion modeling.” Workshop Report, NISTIR 6927,

2003.

Reaction Path Analysis in

Multicomponent Systems

Campbell, C.E., W.J. Boettinger, T. Hansen,

P. Merewether, and B.A. Mueller. “Examination of

multicomponent diffusion between two Ni-base

superalloys.” Properties of Complex Inorganic Solids 3.

Ed. P. Turchi, et al. New York: Kluwer Academic

Publishers, (in press), 2003.

Campbell, C.E., and U.R. Kattner. “Assessment of

the Cr-B system and extrapolation to the Ni-Al-Cr-B

system.” CALPHAD, 26, No. 3, 477–490, 2003.

Bridging Length Scales in Theory and Modeling:

Microstructure Evolution and Material Mechanics

Alikakos, N.D., P.W. Bates, J.W. Cahn, P.C. Fife,

G. Fusco, and G.B. Tangoglu. “Extreme Anisotropy of

Diffusion Interfaces in Crystals.” SIAM Journal of

Applied Mathematics, (in press), 2003.

Boettinger, W.J. “Phase field models for eutectic

solidification.” Journal of Metals, (submitted), 2003.

Boettinger, W.J., J.A. Warren, C. Beckermann, and

A. Karma. “Simulation of solidification.” Annual

Review Materials Research, 32, 163–194, 2002.

Cahn, J.W., and J. Taylor. “A unified approach

to motion of grain boundaries, relative tangential

translation along grain boundaries, and grain rotation.”

Acta Materialia, (in press), 2003.

Foecke, T.J., and D.E. Kramer. “In situ TEM

observations of fracture in nanolaminated metallic thin

films.” International Journal of Fracture, (in press), 2003.

Granasy, L., T. Pusztai, J.A. Warren, J.F. Douglas,

T. Börzönyi, and V. Ferreiro. “Growth of ‘dizzy

dendrites’ in a random field of foreign particles.”

Nature Materials, 2, 92–96, 2003.

Lewis, D.J., W.J. Boettinger, and J.A. Warren.

“Three dimensional phase field modeling of

binary eutectics.” Modeling of Casting, Welding

and Advanced Solidification Processes, X.

Ed. D.M. Stefanescu, J.A. Warren, M.R. Jolly, and

J.M. Drane. Warrendale, PA: TMS, pp. 5–12, 2003.

Lewis, A.C., D. Josell, and T.P. Weihs. “Stability in

thin film multilayers and microlaminates: the role of

free energy, structure, and orientation at interfaces

and grain boundaries.” Scripta Materials, 48 (8),

1079–1085, 1 April 2003.

Lewis, D.J., T. Puztai, L. Granasy, J.A. Warren,

and W.J. Boettinger. “Phase field models for eutectic

solidification.” JOM, (in press), 2003.

Sekerka, R.F., and J.W. Cahn. “Solid–liquid

equilibrium for non-hydrostatic stress.” Acta

Materialia, (submitted), 2003.

Warren, J.A., R. Kobayashi, A.E. Lobkovsky,

and W.C. Carter. “A phase field model of materials

with crystalline interfaces.” Acta Materialia, (in press),

2003.

Warren, J.A., L. Loginova, L. Granasy, T. Borzsonyi,

and T. Pusztai. “Phase field modeling of alloy polycrystals.”

Proceedings for MCWASP Conference, (in press), 2003.

Modeling Solidification, Electrodeposition,

and Microstructure Evolution

Granasy, L., T. Pusztai, T. Borzonyi, J.A. Warren,

B. Kvamme, and P.F. James. “Nucleation and

polycrystalline solidification in binary phase field

theory.” Physics and Chemistry of Glasses, (submitted),

2003.

Electrochemical Processing of

Nanostructure Materials

Ford, A.X., J.E. Bonevich, R.D. McMichael,

M.D. Vaudin, and T.P. Moffat. “Structure and magnetic

properties of electrodeposited Co on n-GaAs(001).”

Journal of Electrochemical Society, (in press), 2003.
60

Metallurgy Division FY03 Annual Report Publication List

Superconformal Film Growth:

Measurement and Modeling

Baker, B.C., M. Feeman, B. Melnick, D. Wheeler,

D. Josell, and T.P. Moffat. “Superconformal

electrodeposition of silver from a KAg(CN)2-KCNKSeCN electrolyte.” Journal of Electrochemical

Society, 150, No. 2, C61–C66, 2003.

Baker, B.C., C. Witt, D. Josell, D. Wheeler, and

T.P. Moffat. “Superconformal silver deposition using

KSeCN derivitized substrates.” Electrochemical and

Solid State Letters, 6, No. 5, C67–C69, 2003.

Josell, D., B. Baker, and C. Witt. “Via filling by

electrodeposition — superconformal silver and copper

and conformal nickel.” Journal of Electrochemical

Society, 149, No. 12, C637–C641, December 2002.

Josell, D., S. Kim, D. Wheeler, T.P. Moffat, and

S.G. Pyo. “Quantifying superconformal filling of the

submicrometer features through surfactant catalyzed

chemical vapor deposition.” Proceedings of 2003

Spring Meeting of Electrochemical Society, (in press),

2003.

Josell, D., S. Kim, D. Wheeler, T.P. Moffat, and

S.G. Pyo. “Interconnect fabrication by superconformal

iodine-catalyzed chemical vapor deposition of copper.”

Journal of Electrochemical Society, 150, No. 5,

C368–C373, 2003.

Josell, D., T.P. Moffat, and D. Wheeler. “An exact,

algebraic solution for the incubation period of superfill.”

Electrochemical Society, (in press), 2003.

Josell, D., D. Wheeler, C. Witt, and T.P. Moffat.

“Seedless superfill: copper electrodeposition in

trenches with ruthenium barriers.” Electrochemical

and Solid State Letters, 6, No. 10, C143–C145, 2003.

McFadden, G.B, S.R. Coriell, T.P. Moffat,

D. Josell, D. Wheeler, W. Schwarzacher, and J. Mallett.

“A mechanism for brightening: linear stability analysis

of the curvature enhanced accelerator coverage model.”

Journal of the Electrochemical Society, 150, No. 9,

C591–C599, 2003.

Moffat, T.P., B.C. Baker, D. Wheeler, and

D. Josell. “Accelerator aging effects during copper

electrodeposition.” Electrochemical and Solid State

Letters, 6, No. 4, C59–C62, 2003.

Moffat, T.P., and D. Josell. “Electrodeposition of

copper in the SPS-PEG-C1 additive system: I. Kinetic

measurements: influence of SPS.” Journal of

Electrochemical Society, (in press), 2003.

Moffat, T.P., D. Wheeler, C. Witt, and D. Josell.

“Superconformal electrodeposition using derivitized

substrates.” Electrochemical Solid State, 5, No. 12,

C110–C112, December, 2002.

Pyo, S.G., S. Kim, D. Wheeler, T.P. Moffat, and

D. Josell. “Seam-free fabrication of submicrometer

copper interconnects by iodine-catalyzed chemical

vapor deposition.” Journal of Applied Physics, 93,

No. 2, 1257–1261, January 15, 2003.

Wheeler, D., D. Josell, and T.P. Moffat. “Modeling

superconformal electrodeposition using the level set

method.” Journal of the Electrochemical Society,

150, No. 5, C302–C310, 2003.

Pb-free Surface Finishes: Sn Whisker Growth

Bogustavsky, I., P. Bush, E. Kam–Lum, M. Kwoka,

J. McCullen, K. Spalding, K. Vo, and M.E. Williams.

“NEMI tin whisker test method standards.” SMTAI

Proceedings, (submitted), 2003.

Moon, K., C.E. Johnson, M.E. Williams, O. Kongstein,

G.R. Stafford, C.A. Handwerker, and W.J. Boettinger.

“Observed correlation of Sn oxide film to Sn whisker

growth in Sn-Cu electrodeposit for Pb-free Solders.”

Journal of Electronic Materials, (in press), 2003.

Pb-free Solders and Solderability

Bertocci, U. “An EQMB examination of Cu

surface oxides in borate buffer.” Electrochemica Acta,

(submitted), 2003.

Boettinger, W.J., M.D. Vaudin, M.E. Williams,

L.A. Bendersky, and W.R. Wagner. “EBSD and EDS

study of the phase NiSn4.” Journal of Electronic

Materials, 32, 511–515, 2003.

Bradley, E., C.A. Handwerker, and J. Sohn.

“Lead-free solder alloys: NEMI recommendation.”

Circuits Assembly, (in press), 2003.

Kattner, U.R. “Phase diagrams for solder alloys.”

Journal of Materials, 54 (12), 45–51, 2002.

Schaefer, R.J., and D.J. Lewis. “Directional

solidification in a AgCuSn eutectic alloy.” Journal of

Electronic Materials, (in press), 2003.

Solder and Solderability Measurements

for Microelectronics

Handwerker, C.A., J. Bath, E. Benedetto, E. Bradley,

R. Gedney, T.A. Siewert, P. Snugovsky, and J. Sohn.

“NEMI Lead-Free Assembly Project: comparison between

PbSn and SnAgCu reliability and microstructures.”

SMTAI Proceedings, (in press), 2003.
61

Metallurgy Division FY03 Annual Report Publication List

Magnetic Properties and

Standard Reference Materials

Rao S., L.H. Bennett, E. Della Torre, A.P. Chen, and

R.A. Fry. “Fluctuating field calculation for a bimodal

medium.” Journal of Applied Physics, 93, No. 10,

7798–7800, 2003.

Magnetic Properties of Nanostructured

Materials

Kabanov, Y.P., V.S. Gornakov, V.I. Nikitenko,

A.J. Shapiro, and R.D. Shull. “Nucleation and evolution

of hybrid spin spiral in soft/hard ferromagnetic bilayer.”

Journal of Applied Physics, 93, 8244, 2003.

King, T.T., B.A. Rowlett, R.A. Ramirez, P.J. Sirron,

E.R. Canavan, M.J. DiPirro, J.S. Panek, J.G. Tuttle,

R.D. Shull, and R.A. Fry. “Rare-earth garnets and

perovskites for space-based ADR cooling at high T

and low H.” AIP Conference Proceedings, 613,

1191, 2002.

Nikitenko, V.I., V.S. Gornakov, Y.P. Kabanov,

A.J. Shaper, R.D. Shull, C.L. Chien, J.S. Jiang, and

S.D. Bader. “Magneto-optic indicator film study of

the hybrid exchange spring formation and evolution

processes.” Journal of Magnetism and Magnetic

Materials, 19, 258–259, 2003.

Provenzano, V., J. Li, T.T. King, E.R. Canavan,

P. Shirron, M.J. DiPorrp, and R.D. Shull. “Enhanced

magnetocaloric effects in R3(Ga1–xFex)5O12 (R = Gd,

Dy, Ho); (O<x<1) nanocomposites.” Journal of

Magnetism and Magnetic Materials, (in press), 2003.

Shir, F., L. Yanik, L.H. Bennett, E. Della Torre, and

R.D. Shull. “Room temperature active regenerative

magnetic refrigeration: magnetic nanocomposites.”

Journal of Applied Physics, 93, 8295, 2003.

Shull, R.D., A.J. Shapiro, V.S. Gornakov,

V.I. Nikitenko, and H.W. Zhao. “Stationary

antiferromagnetic domains during magnetization

reversal in an exchange-biased FeMn/Fe76 Mn6C18

bilayer.” Journal of Applied Physics, 93, 8603, 2003.

Taketomi, S. and R.D. Shull. “Experimental

verification of interactions between randomly

distributed fine magnetic particles.” Journal of

Magnetism and Magnetic Materials, (in press), 2003.

Taketomi, S., A.J. Shaper, and R.D. Shull.

“Structural effects on the magnetic character of

yttrium–iron–garnet nanoparticles dispersed in glass

composites.” Journal of Applied Physics, 93, 7199,

2003.

Zheng, L.A., E.V. Barrera, and R.D. Shull.

“Magnetic properties of the Co-C(d60) and Fe-C(d60)

nanocrystalline magnetic thin films.” Journal of

Applied Physics, (submitted), 2003.

Nanomagnetodynamics

Della Torre, E., and L.H. Bennett. “Thermal

longevity of nano-multilayer magnetic media.”

Proceedings of the 2002 2nd IEEE Conference on

Nanotechnology, Piscataway, New Jersey, pp. 71–74,

2003.

Kunz, A., and R.D. McMichael. “Normal mode

mixing and ferromagnetic resonance linewidth.”

IEEE Transactions of Magnetics, 38, No. 5,

2400–2402, (in press), 2002.

McMichael, R.D. “A classical model of extrinsic

ferromagnetic resonance linewidth in ultra-thin films.”

IEEE Transactions on Magnetics, (submitted), 2003.

McMichael, R.D., A. Kunz, and D.J. Twisselmann.

“Localized ferromagnetic resonance in inhomogeneous

thin films.” Physical Review Letters, Vol. 90,

Art. No. 227601, 2003.

New Materials for High Density Data Storage

Bae, S., J.H. Judy, P.J. Chen, and W.F. Egelhoff, Jr.

“Dependence of physical properties and giant

magnetoresistance ratio on substrate position during

rf sputtering of NiO and alpha-Fe2O3 for bottom spin

valves.” Applied Physics Letters, 81, 2208, 2002.

Bae, S., J.H. Judy, P.J. Chen, L. Gan,

W.F. Egelhoff, Jr., J. Hautala, and D.B. Fenner.

“Effects of Ar gas cluster ion beam (GCIB) processing

on surface roughness, crystalline orientation texture,

magnetic, and giant magnetoresistance (GMR)

properties of reactively RF sputtered, alpha-Fe2O3

bottom GMR spin valves.” IEEE Transactions of

Magnetics, (in press), 2003.

Bae, S., P.J. Chen, W.F. Egelhoff, Jr., and J.H. Judy.

“Effects of sputtering angle on surface roughness,

chemical composition, and GMR behavior of NiO and

alpha-Fe2O3 bottom spin-valves.” IEEE Transactions

of Magnetics, (in press), 2003.

Buchanan, J.D.R., T.P.A. Hase, B.K. Tanner,

P.J. Chen, L. Gan, C.J. Powell, and W.F. Egelhoff, Jr.

“Anomalously large intermixing in aluminum-transition

metal bilayers.” Physical Review B, Vol. 66,

Art. No. 104427, 2002.
62

Metallurgy Division FY03 Annual Report Publication List

Buchanan, J.D.R., T.P.A. Hase, B.K. Tanner,

P.J. Chen, L. Gan, C.J. Powell, and W.F. Egelhoff, Jr.

“Intermixing of aluminum-magnetic transition metal

bilayers.” Journal of Applied Physics, 93, 8044, 2003.

Carrey, J., A.E. Berkowitz, W.F. Egelhoff, Jr., and

D. Smith. “Influence of interface alloying on the

magnetic properties of Co/Pd multilayers.” Applied

Physics Letters, (submitted), 2003.

Chopra, H.D., D.X. Yang, P.J. Chen, and

W.F. Egelhoff, Jr. “Domain structure and

magnetoelastic properties of Fe/Pd ferromagnetic

thin films and multilayers.” Journal of Applied

Physics, (in press), 2003.

Gan, L., R.D. Gomez, A. Castillo, P.J. Chen,

C.J. Powell, and W.F. Egelhoff, Jr. “Ultra-thin

aluminum oxide as a thermal oxidation barrier on

metal films.” Thin Solid Films, 415, 219, 2002.

Gan, L., R.D. Gomez, C.J. Powell, R.D. McMichael,

P.J. Chen, and W.F. Egelhoff, Jr. “Thin Al, Au, Cu,

Ni, Ta, and Fe films as oxidation barriers for the

Co surface in air.” Journal of Applied Physics,

93, 8731, 2003.

Gan, L., R.D. McMichael, P.J. Chen, W.F. Egelhoff,

Jr., and G.C. Lee. “Ultra-thin aluminum oxide as a

thermal oxidation barrier on metal films.” Thin Solid

Films, 414, 219, 2002.

Chung, S.H., N. Garcia, W.F. Egelhoff, Jr.,

and R.D. Gomez. “Universal behavior of ballistic

magnetoresistance versus scaled conductance in

atomic nanocontacts.” Physical Review Letters,

Vol. 89, Art. No. 287203, 2002.

Chung, S.H., N. Garcia, W.F. Egelhoff, Jr., and

R.D. Gomez. “Universal scaling of magnetoconductance

in magnetic nanocontacts.” Journal of Applied Physics,

93, 7939, 2003.

Gornakov, V.S., V.I. Nikitenko, W.F. Egelhoff, Jr.,

R.D. McMichael, A.J. Shapiro, and R.D. Shull.

“Ru spacer thickness dependences of the domain

nucleation and growth in Co/Ru/Co synthetic

antiferromagnet.” Journal of Magnetism and

Magnetic Materials, 258, 345 (2003).

Huang, H., K. Seu, W.F. Egelhoff, Jr., and A. Reilly.

“Ultrafast pump-probe laser spectroscopy of the

half-metal CrO2.” Journal of Applied Physics,

(in press), 2003.

Lee, C.G., J.-G. Jung, V.S. Gornakov, R.D. McMichael,

A. Chen, and W.F. Egelhoff, Jr. “Effects of annealing

on the GMR and domain structure stabilization in a

Py/Cu/Py/MnIr spin valve.” Journal of Magnetism

and Magnetic Materials, (in press), 2003.

Mallett, J.J., E.B. Svedberg, H. Ettedgui,

T.P. Moffat, and W.F. Egelhoff, Jr. “A search for

ballistic magnetoresistance (BMR) in electrodeposited

Ni nanocontacts: feedback control used to select

the contact resistance.” Applied Physical Letters,

(in press), 2003.

Osofsky, M.S., R.J. Soulen, Jr., G. Woods, and

W.F. Egelhoff, Jr. “Enhanced Tc near the metal/insulator

transition: new insight into novel superconducting

Materials.” Physical Review Letters, (in press), 2003.

Rezende, S.M, A. Azevedo, F.M. de Aguiar,

J.R. Fermin, W.F. Egelhoff, Jr., and S.S.P. Parkin.

“Three-layer model for exchange anisotropy.”

Physical Review B, Vol. 66, Art. No. 064109, 2002.

Sanz, M., A. Papageorgopoulos, W.F. Egelhoff, Jr.,

M. Nieto-Vesperinas, and N. Garcia. “Wedge-shaped

absorbing samples look left handed: the problem of

interpreting negative refraction, and its solution,”

Physical Review B, (in press), 2003.

Seu, K., H. Huang, J.L. Showman, H. Showman,

W.F. Egelhoff, Jr., and A. Reilly. “Co layer thickness

dependence of exchange biasing of IrMn/Co and

FeMn/Co.” Journal of Applied Physics, 93, 6611, 2003.

Siu, I.L., W.F. Egelhoff, Jr., H.D. Chopra, and

D.X. Wang. “Magnetization reversal in epitaxial CrO2

films.” Journal of Applied Physics, 92, 5409, 2002.

Svedberg, E.B., J.J. Mallett, H. Ettedgui,

L. Gan, P.J. Chen, A.J. Shapiro, T.P. Moffat, and

W.F. Egelhoff, Jr. “Possible ballistic magnetoresistancelike artifacts in electrodeposited nanocontacts.”

Journal of Applied Physics, (in press), 2003.

Torok, E.J., S. Zurn, S. Bae, P.J. Chen,

W.F. Egelhoff, Jr., L.E. Sheppard, R. Spitzer, and

J.H. Judy. “Transpinnor: a new giant magnetoresistive

spin-valve device.” Applied Physics, 91, 8414, 2002.

Vaz, C.F.A., E. Blackburn, M. Klaui, J.A.C. Bland,

W.F. Egelhoff, Jr., E. Cambril, G. Faini, and

W. Wernsdorfer. “Magnetoresistance magnetometry

of (Ni80Fe20)1–xIrx wires with varying anisotropic

magnetoresistance ratio.” Journal of Applied Physics,

93, 8104, 2003.

Woods, G.T., R.J. Soulen, Jr., I.I. Mazin,

B. Nadgorny, M.S. Osofsky, J. Sanders, H. Srikanth,

W.F. Egelhoff, Jr., and R. Datla. “Analysis of

point-contact Andreev reflection spectra in spin

polarization measurements.” Physical Review B,

(in press), 2003.
63

Metallurgy Division FY03 Annual Report Publication List

Yang, D.X., E.J. Repetski, H.D. Chopra, B.J. Spencer,

D.C. Parks, P.J. Chen, and W.F. Egelhoff, Jr. “A pinhole

coupling strength in giant magnetoresistance spin valves:

a statistical approach.” Physical Review B, (in press),

2003.

Yang, D.X., E.J. Repetski, H.D. Chopra, P.J. Chen,

and W.F. Egelhoff, Jr. “Highly deleterious role of small

amounts of carbon in the giant magnetoresistance

effect.” Journal of Applied Physics, 93, 8415, 2003.

Hardness Standardization —

Rockwell, Vickers, Knoop

Barbato, G., A. Germak, K. Herrmann, and S.R. Low.

“Evolutions in hardness scales definition.” Proceedings

of XVII IMEKO World Congress, Dubrovnik, Croatia,

June 22–27, pp. 978–981, 2003.

Barbato, G., A. Germak, and S.R. Low. “Proposal

for a practical procedure for the expression of

uncertainty in hardness measurement.” Proceedings of

XVII IMEKO World Congress, Dubrovnik, Croatia,

June 22–27, pp. 986–991, 2003.

Jiang, J.S., S.D. Bader, H. Kaper, G.K. Leaf,

R.D. Shull, A.J. Shapiro, V.S. Gornakov, V.I. Nikitenko,

C.L. Platt, A.E. Berkowitz, S. David, and E.E. Fullerton.

“Rotational hysteresis of exchange-spring magnets.”

Journal of Physics, D35, 2339, 2002.

Low, S.R., and J. Fink. “Effects of bending in

brass Rockwell B scale test blocks.” Proceedings of

XVII IMEKO World Congress, Dubrovnik, Croatia,

June 22–27, pp. 1030–1033, 2003.

Ma, L., S.R. Low, and J. Song. “Determining

mechanical properties of O1 tool steel from reverse

computation of indentation measurement.” Proceedings

of XVII IMEKO World Congress, Dubrovnik, Croatia,

June 22–27, pp. 1005–1008, 2003.

Ma, L., S.R. Low, and J. Song. “FEA modeling

and experimental comparisons of deformable ball

indenters; effect on Rockwell B Hardness (HRB) tests.”

Journal of Testing and Evaluation, Vol. 31 (6),

(in press), November 2003.

Ma, L., J. Zhou, A. Lau, S. Low, and R. deWit.

“Self-similarity simplification approaches for the

modeling and analysis of Rockwell Hardness indentation.”

Journal of Research of the National Institute of

Standards and Technology, 107 (5), 401–412,

September–October 2002.

Ma, L., S. Low, J. Zhou, J., J. Song, and R. deWit.

“Simulation and prediction of hardness performance

of Rockwell diamond indenters using finite element

analysis.” Journal of Testing and Evaluation, 30 (4),

265–273, July 2002.

Nanoscale Characterization by

Electron Microscopy

Chen, M., L. Sun, J.E. Bonevich, D.H. Reich,

C.L. Chien, and P.C. Searson. “Tuning the magnetic

properties of multilayer nanowires.” Applied Physics

Letters, 82, 3310, 2003.

Chong, Y., P.D. Dresselhaus, S.P. Benz, and

J.E. Bonevich. “Effects of interlayer electrode

thickness in Nb/(MoSi2/Nb)N stacked Josephson

junctions.” Applied Physics Letters, 82, 2467, 2003.

Kramer, D.E., M.F. Savage, A. Lin, and T.J. Foecke.

“Novel method for TEM characterization of

deformation under nanoindents in nanolayered

materials.” Scripta Materialia, (submitted), 2003.

Lehman, S.Y., A. Roshko, R.P. Mirin, and

J.E. Bonevich. “Investigation of the shape of

InGaAs/GaAs quantum dots.” Proceedings of

Materials Research Society, Vol. 737, (in press), 2003.

Shin, K., H. Wang, S.K. Satija, C.C. Han, D. Josell,

and J.E. Bonevich. “Rapid deformation of thin

gold layers in polymer matrices studied by X-ray

reflectivity.” Journal of Applied Physics, 94 (3),

2115–2122, August 1, 2003.

Other

Basak, D., R.A. Overfelt, and D. Wang.

“Measurement of specific heat capacity and electrical

resistivity of industrial alloys using pulse heating

techniques.” International Journal of Thermophysics,

(in press), 2003.

Bobordis, K., A. Seifter, A.W. Obst, and D. Basak.

“Radiance temperatures and normal spectral emittances

(in the wavelength range of 1500 nm to 5000 nm) of

tin, zinc, aluminum, and silver at their melting points by

a pulse-heating technique.” International Journal of

Thermophysics, (in press), 2003.

Bobordis, K., A. Seifter, A.W. Obst, and D. Basak.

“Validation of a new high-speed fiber-coupled

four-wavelength infrared pyrometer in the range of

505 k to 1234 k by a pulse-heating technique, using

the melting points of tin, zinc, aluminum, and silver

as reference points.” International Journal of

Thermophysics, (in press), 2003.

Boettinger, W.J., C.E. Campbell, T. Hansen,

P. Merewether, and B.A. Mueller. “Properties of complex

inorganic solids.” Ed. P.E.A. Turchi, A. Gonis, A. Meike,

and K. Ragan. New York: Kluwer Academics/Plenum

Publishers, (in press), 2003.
64

Metallurgy Division FY03 Annual Report Publication List

Gayle, F.W. “FY2002 programs and accomplishments:

MSEL materials for micro- and optoelectronics.”

NISTIR 6971, 2003.

Hooper, J.J., T.J. Foecke, L. Graham, and T.P. Weihs.

“Metallurgical analysis of wrought iron from the RMS

titanic.” Marine Technology, (in press), 2003.

Kass, M., C.R. Brooks, D. Falcon, and D. Basak.

“The formation of defects in Fe-Al alloys: electrical

resistivity and specific heat measurements.”

Intermetallics, 10, 951–966, 2002.

Kramer, D.E., and T. Foecke. “Observations of

deformation and fracture in metallic nanolaminates.”

Philosophical Magazine A, 82, No. 17–18, 3375–3381,

2002.

Park, J.-K., D.-Y. Kim, H.-Y. Lee, J.E. Blendell,

and C.A. Handwerker. “Crystallographic orientation

dependent dissolution behavior of sapphire in anorthite

liquid containing Cr2O3.” Journal of the American

Ceramic Society, 86 (6), 1014–1018, 2003.

Ricker, R.E. “Modeling the influence of crack

path deviations on the propagation of stress corrosion

cracks.” Hydrogen Effects on Materials Behavior and

Corrosion Deformation Interactions. Ed. N.R. Moody,

A.W. Thompson, R.E. Ricker, G.S. Was, and R.H. Jones.

Warrendale, PA: TMS, (in press), 2003.

Ricker, R.E., and A.K. Vasudevan. “The influence

of grain boundary precipitation on the stress corrosion

cracking of Al-Li and Al-Li-Cu alloys.” Hydrogen

Effects on Materials Behavior and Corrosion

Deformation Interactions. Ed. N.R. Moody,

A.W. Thompson, R.E. Ricker, G.S. Was, and R.H. Jones.

Warrendale, PA: TMS, (in press), 2003.

Stafford, G.R., T. Tsuda, and C.L. Hussey.

“Order/disorder in electrodeposited aluminum–titanium

alloys.” Journal of Mining and Metallurgy, 39,

Issue 1–2B, 23–42, 2003.

Song, J., L. Ma, E. Whitenton, and T. Vorburger.

“Bullet signature measurement at NIST.” Proceedings

of Measurement Science Conference, Anaheim,

California, January 2003.

Song, J., T. Voburger, R. Clary, E. Whitenton, L. Ma,

and S. Ballou. “Standards for bullets and casings.”

Materials Today, pp. 26–31, November 2002.

Stoudt, M.R., and R.E. Ricker. “Evaluating corrosion

fatigue behavior through innovative electrochemical

analyses.” Metallurgical and Materials Transactions A,

(in press), 2003.

Tsuda, T., C.L. Hussey, G.R. Stafford, and

J.E. Bonevich. “Electrochemistry of titanium and

the electrodeposition of Al-Ti alloys in the Lewis acid

aluminum chloride-1 ethyl-3-methylimidazolium chloride

melt.” Journal of Electrochemical Society, 150, C234,

2003.

William, M.E., W.J. Boettinger, and U.R. Kattner.

“Contribution to the Zn-rich part of the Zn-Zr phase

diagram.” Journal of Phase Equilibria, (submitted),

2003.
65

Metallurgy Division

Metallurgy Division

Chief

Carol A. Handwerker

Phone: 301–975–6158

E-mail: carol.handwerker@nist.gov

Deputy Chief

Frank W. Gayle

Phone: 301–975–6161

E-mail: frank.gayle@nist.gov

NIST Fellows

William J. Boettinger

Phone: 301–975–6160

E-mail: william.boettinger@nist.gov

John W. Cahn

Phone: 301–975–5664

E-mail: john.cahn@nist.gov

Group Leaders

Electrochemical Processing Group

Gery R. Stafford

Phone: 301–975–6412

E-mail: gery.stafford@nist.gov

Magnetic Materials Group

Robert D. Shull

Phone: 301–975–6035

E-mail: robert.shull@nist.gov

Materials Performance Group

Stephen D. Ridder

Phone: 301–975–6175

E-mail: stephen.ridder@nist.gov

Materials Structure and Characterization Group

Frank W. Gayle

Phone: 301–975–6161

E-mail: frank.gayle@nist.gov

Metallurgical Processing Group

Stephen D. Ridder

Phone: 301–975–6175

E-mail: stephen.ridder@nist.gov
66

Research Staff

Research Staff

Claggett, Sandra W.

sandra.claggett@nist.gov

Specimen preparation for electron microscopy

Digital imaging

Specimen preparation for scanning electron

microscopy

Image analysis

Metallography of materials

Specimen preparation for transmission of

electron microscopy

Drew, Rosetta V.

rosetta.drew@nist.gov

Magnetometry

Database maintenance

Egelhoff Jr., William F.

william.egelhoff@nist.gov

Giant magnetoresistance

Molecular beam epitaxy

Surface physics

Ultrahigh density data storage

Fields, Richard J.

richard.fields@nist.gov

Mechanical properties

Mechanical testing

Powder consolidation

Metal forming

Fink, James L.

james.fink@nist.gov

Hardness standards

Hardness testing

Mechanical properties measurement

Metal powder consolidation

Environmental corrosion

Metallography

Foecke, Timothy J.

timothy.foecke@nist.gov

Metal forming standards

Nanostructured materials

Experimental fracture physics

SEM, TEM, SPM

Micro- and nano-mechanics of materials

Dislocation-based deformation mechanisms

Historical metallurgy and failure analysis

Gates, Hilary G.

hilary.gates@nist.gov

Standard reference materials

Banovic, Stephen W.

stephen.banovic@nost.gov

Metal forming

Mechanical properties

Texture analysis

Beauchamp, Carlos R.

carlos.beauchamp@nist.gov

Compositionally modulated alloys

Standard reference materials

Baker, Brett C.

brett.baker@nist.gov

Deposition of metals/alloys

Bendersky, Leonid A.

leonid.bendersky@nist.gov

Functional ceramics

Analytical and high-resolution TEM

High-temperature intermetallics

Combinatorial methods

Biancaniello, Frank S.

frank.biancaniello@nist.gov

Spray deposition measurements and diagnostics

Inert gas atomization: metal powder

measurements and consolidation

Nitrogenated steels, standard reference materials

Special alloys, bulk metallic glasses

Biomaterials

Boettinger, William J.

william.boettinger@nist.gov

Relation of alloy microstructures to processing

conditions; solidification

Thermal analysis

Solder

Bonevich, John E.

john.bonevich@nist.gov

Electron holography

Interfacial structure and chemistry

High resolution/analytical electron microscopy

Magnetic materials

Campbell, Carelyn E.

carelyn.campbell@nist.gov

Transient liquid phase bonding

Multicomponent diffusions simulations

Alloy design methodology
67

Research Staff

Gayle, Frank W.

frank.gayle@nist.gov

Structure/property relationships

Transmission electron microscopy

Aluminum metallurgy

Solder science

Guyer, Jonathan E.

jonathan.guyer@nist.gov

III–V semiconductors

Molecular beam epitaxy

Alloy film deposition

Stress-induced mass transport

Handwerker, Carol A.

carol.handwerker@nist.gov

Interface thermodynamics and kinetics

Solder science

Microstructure evolution

Jiggetts, Rodney D.

rodney.jiggetts@nist.gov

Substrate analysis

Grit blasting

Roughness measurements

Metallography of coatings

Image analysis

Micro analysis/characterization

Hot isostatic processing

Johnson, Christian E.

christian.johnson@nist.gov

Ultra-black coatings

Electroless deposition processes

Metallic glass alloy deposition

Microhardness SRM research

Chromium deposition

Pulse alloy deposition

Lead-free solder

Josell, Daniel

daniel.josell@nist.gov

Mechanical and thermal properties of

multi-layer materials

Measurement and modeling of solder joint

geometries

Filling of sub-0.1 mm features by

electrodeposition

Kattner, Ursula R.

ursula.kattner@nist.gov

Computational thermodynamics

Alloy phase equilibria evaluations

Solder alloy systems

Superalloy systems

Kelley, David R.

david.kelley@nist.gov

Microhardness SRM development

Dye penetration SRM development

Precious metal electrodeposition

Plating on aluminum

Electroplating

Levine, Lyle E.

lyle.levine@nist.gov

Diffraction theory

Dislocation-based deformation

Synchrotron x-ray techniques

Percolation theory

TEM, SEM, SPM

Lewis, Daniel J.

daniel.lewis@nist.gov

Modeling of eutectic solidification

Electric packaging

Low, II, Samuel R.

samuel.low@nist.gov

Hardness standards

Hardness testing

Mechanical properties of materials

Mechanical testing of materials

Luecke, William E.

william.luecke@nist.gov

High temperature mechanical testing

Creep of ceramics

Silicon nitride

Mates, Steven P.

steven.mates@nist.gov

Compressible fluid flow

Metal sprays

Fluid flow visualization

McMichael, Robert D.

robert.mcmichael@nist.gov

Giant magnetoresistance

Micromagnetic modeling

Ferromagnetic resonance

Nanocomposites

Moffat, Thomas P.

thomas.moffat@nist.gov

Electrochemistry

Scanning probe microscopy

Nanostructures

Pierce, Jr., Thomas A.

tpierce@nist.gov

Hardness measurements

Metallography
68

Research Staff

Pitchure, David J.

david.pitchure@nist.gov

Mechanical testing

Computer-aided design

Mechanical engineering

Ricker, Richard E.

richard.ricker@nist.gov

Corrosion

Deformation mechanisms

Fracture mechanisms (SCC, CF HE)

TEM, SEM

Ridder, Stephen D.

stephen.ridder@nist.gov

Spray dynamics and deposition

Thermal spray processes

Process modeling and control

Shapiro, Alexander J.

alexander.shapiro@nist.gov

MOIF method microscopy

Mossbauer effect

Scanning electron microscopy (SEM) and

x-ray microanalysis

Image analysis

Shepherd, Dominique A.

dominique.shepherd@nist.gov

Titanium allloys

Mechanical testing

Mechanical properties

SEM, TEM

Shull, Robert D.

robert.shull@nist.gov

Nanocomposites

Magnetic susceptibility

Mossbauer effect

X-ray and neutron diffraction

Magneto-caloric and magneto-optical effects

Magnetic domain imaging

Stafford, Gery R.

gery.stafford@nist.gov

Electrochemical transients

Electrodeposition

Molten salt electrochemistry

Stoudt, Mark R.

mark.stoudt@nist.gov

Deformation-induced surface roughness

Mechanical properties

Metal fatigue

Thin films

Environmentally assisted cracking

Twisselmann, Douglas J.

douglas.twisselmann@nist.gov

Ferromagnetic resonance

Magnetometry

Warren, James A.

james.warren@nist.gov

Computer simulations of solidification

Dendrite pattern formation

Modeling of solder/substrate wetting processes

Modeling grain boundaries

Williams, Maureen E.

maureen.williams@nist.gov

Differential thermal analysis

Powder x-ray diffraction

Solder Wettability

SEM
69

Organizational Charts

Organizational Charts

Materials Science and Engineering Laboratory

Polymers

E.J. Amis, Chief

C.R. Snyder, Deputy

Metallurgy

C.A. Handwerker, Chief

F.W. Gayle, Deputy

Ceramics

D.L. Kaiser, Chief

D.R. Black, Deputy

Materials Reliability

A.F. Clark, Chief

T.A. Siewert, Deputy

NIST Center for

Neutron Research

J.M. Rowe, Director

Director

Deputy Director

National Institute of Standards and Technology

Director

Boulder Laboratories

Baldrige National Quality

Program

Director for

Administration

& Chief Financial

Officer

Technology

Services

Advanced

Technology

Program

Manufacturing

Extension

Partnership

Manufacturing

Engineering

Laboratory

Chemical Science

and Technology

Laboratory

Materials Science

and Engineering

Laboratory

Electronics and

Electrical Engineering

Laboratory

Information

Technology

Laboratory

Physics

Laboratory

Building and

Fire Research

Laboratory

L.E. Smith, Director

S.W. Freiman, Deputy Director