NATIONAL INSTITUTE OF STANDARDS &

TECHNOLOGY

Research Information Center

Gaithersburg, MD 2089# /

IMSE

NBS

PUBUCATIONS

Institute for Materials Science and Engineering

A111D2 715305

METALLURGY

NAS-NRC

Assessment Panel

January 21-22, 1988

NBSIR 87-3615

U.S. Department of Commerce

National Bureau of Standards

Technical Activities

1987

Institute for Materials Science and Engineering

ME1ALLURGY

E.N. Pugh, Chief

J.H. Smith, Deputy

NAS-NRC

Assessment Panel

January 21-22, 1988

Research Information Center

National Bureau of Standards

Gaithersburg, Maryland 20899

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NBSIR 87-3615

U.S. Department of Commerce

National Bureau of Standards

Technical Activities

1987
METALLURGY DIVISION

CHIEF

E. Neville Pugh

Phone: (301) 975-5960

DEPUTY CHIEF

John H. Smith

Phone: (301) 975-5961

GROUP LEADERS

Metallurgical Processing

John R. Manning

Phone: (301) 975-6157

Corrosion and Wear

Arthur W. Ruff

Phone: (301) 975-6010

Metallurgical Structure

John B. Clark

Phone: (301) 975-6040

Electrodeposition

David So Lashmore

Phone: (301) 975-6405

Nondestructive Characterization

Haydn No G. Wadley

Phone: (301) 975-6140

Magnetic Materials

Lawrence H. Bennett

Phone: (301) 975-5966

ii
ABSTRACT

This report summarizes the FY 1987 activities of the Metallurgy

Division of the National Bureau of Standards. The research centers

upon the structure-processing-properties relations of metals and

alloys and on the methods of their measurement. The activities also

include the generation and evaluation of critical materials data.

Efforts comprise studies of metallurgical processing, corrosion and

wear, chemical metallurgy, electrodeposition, nondestructive

characterization and magnetic materials.

The work described also includes four cooperative programs with

American professional societies and industry: the ASM INTERNATIONAL

(ASM) - NBS Alloy Phase Diagram Program, the National Association of

Corrosion Engineers (NACE) - NBS Corrosion Data Program, the

American Iron and Steel Institute (AISI) - NBS Steel Sensor Program,

and the Aluminum Association - NBS Temperature Sensor Program.

Work in support of other government agencies includes a major

program to assist the Nuclear Regulatory Commission in addressing

the critical national problem of disposing of high level nuclear

waste in geologic repositories.

The scientific publications, committee participation, and other

professional interactions of the 72 full-time and part-time

permanent members of the Metallurgy Division and its 40 guest

researchers are identified.

iii

TABLE OF CONTENTS

PAGE

OVERVIEW . . . . . . . . . o . ... . . . . . . . . . « . o . . 1

METALLURGY DIVISION

ORGANIZATION CHART ....................... 5

RESEARCH STAFF ......................... 6

TECHNICAL ACTIVITIES

Metallurgical Processing ................. 13

Corrosion and Wear .................... 25

Metallurgical Structure .................. 39

Electrodeposition ..................... 43

Nondestructive Characterization .............. 57

Magnetic Materials .................... 75

OUTPUTS / INTERACTIONS

Recent Publications .................... 79

Industrial and Academic Interactions ........... 91

Technical/Professional Committee

Leadership Activities ................... 97

External Recognition and Awards .............. 102

APPENDIX

Organizational Chart

National Bureau of Standards ............... A1

Organizational Chart

Institute for Materials Science and Engineering ...... A2

v

OVERVIEW

METALLURGY DIVISION (420)

E. Neville Pugh, Chief

John H. Smith, Deputy Chief

June Toms, Secretary

In keeping with the Bureau's traditional role, the Metallurgy Division

continues to generate measurement methods, critical materials data and

standards to support U.S. industry, government and universities . In the area

of measurement science, work on process sensors is leading to more direct

interaction with industry and to a growing activity in intelligent materials

processing. The Division's research programs support our measurement

activities and, in addition, are moving increasingly to address the science

base underlying both traditional and new materials technologies, a trend

which is also leading to more direct interaction with industry. Our

involvement with other government agencies also continues to grow and, in

particular, the Division is providing technical assistance in several

critical areas, each closely related to our specific research expertise.

These diverse activities are summarized here and described in more detail in

the narratives of the Division's six groups.

The work on process sensors was highlighted by the successful testing of a prototype eddy current device for determining the internal temperature of

aluminum during extrusion. This activity, carried out in the Nondestructive

Characterization Group in collaboration with the Aluminum Association, led to

tests in an industrial processing plant. A modified version of this sensor

has been used to measure density in situ during hot-isostatic pressing

(HIPing) of several materials including titanium-aluminide intermetallic

alloys and high Tc superconductors. In the same Group, the use of ultrasonic

time of flight tomography is being extended to the determination of the

position of the liquid-solid interface in partially solidified material, a program being carried out with the American Iron and Steel Institute. In the

Metallurgical Processing Group, a consortium has been established with

several companies to develop sensors to measure powder size and distribution

in real time during the production of powders in our high pressure inert gas

atomizer. This program also involves modeling of the atomization process and

is aimed ultimately at automated control of the process.

Metal matrix composites represent an important emerging technology in which

we have mounted a significant effort. The performance of such composites is

critically dependent on the mechanical properties of the interface between

the matrix and the reinforcing phase, and our studies have focussed on this

factor, particularly in composites consisting of SiC fibers in an A1 alloy

matrix. Several Groups have interacted in this effort. In the

Nondestructive Characterization Group, a technique has been perfected to

prepare a sample consisting of an A1 monocrystal containing a single SiC

1
fiber. This sample has permitted fundamental studies of the mechanical

properties of the interface using acoustic emission techniques and has been

used for ultrasonic studies of "leaky" waves in the interface region to

investigate the perfection of the interface. Thermodynamic modeling of

stresses generated by interdiffusion at the interfaces are being conducted by

the Metallurgical Processing Group. Another unusual approach being pursed is

to electrodeposit the A1 alloy onto the fiber, and thus the Electrodeposition

Group is playing a lead role. In addition to investigating the properties of

electrodeposited A1 alloys, their activities include modeling of the alloy

deposition process on moving fibers, and studies of the feasibility of

producing compositionally graded alloys to minimize interfacial stresses.

Data programs continued to be an important component of the Division's

activities in FY87. In the Alloy phase Diagram Data Program, set up

cooperatively with the ASM International to provide critically evaluated

phase diagrams, the year was highlighted by the publication of a two volume

compendium of evaluated binary diagrams which updates Hansen's classical

compilation. In addition, a relational database of the critical data for

nearly 1600 diagrams is ready for on-line search and is being transferred to

ASM INTERNATIONAL. The NACE-NBS Corrosion Data Center continues as a focal

point of corrosion data to characterize corrosion performance of engineering

materials over a wide variety of environments and exposure conditions.

Programming of NACE survey data on nonmetals has been completed and resulting

software is being marketed by NACE as CORSUR Corrosion Data Software. With

assistance from the Center for Applied Mathematics, PC software has been

developed utilizing the stability diagram programs (Pourbaix diagrams)

originally created at the University of Florida to study corrosion

thermodynamics. A Tribology Data Program has been established with joint

sponsorship of the Department of Energy, the American Society of Mechanical

Engineers, and the American Society of Lubrication Engineers. Abrasive wear

coefficients have been evaluated for a group of frequently used metals under

standard wear test conditions and assembled into a data base for use in the

PC based Tribology and Information System (ACTIS).

A broad range of activities involving other government agencies was conducted

in FY87, some in support of our basic research programs and others which

provide technical support to the agencies in areas of our expertise. The

former is exemplified by studies in the Metallurgical Processing Group of

interfaces for application to metal matrix composites and studies of stress

effects on alloy coarsening funded at NBS by the Office of Naval Research. A new program on high temperature alloys and intermetallics is being supported

by the Defense Advanced Research Projects Agency. Work on powder processing

of rapidly solidified alloys was funded during the past year by the Naval Air

Development Center. An example of technical support of another agency is the

effort in the Corrosion Group to assist the Nuclear Regulatory Commission in

the critical national problem of developing geologic repositories for high

level nuclear waste. Pitting and stress corrosion cracking are major

processes which threaten the integrity of the metallic waste containers, and

these phenomena have been central to the research interests of the Corrosion

Group for some years. Another example of our research expertise providing

2
direct assistance has been in the application of advanced electrodeposition

techniques to the development of wear-resistant chromium coatings for the

Bureau of Engraving and Printing to be used in currency printing plates.

Our staff and their areas of expertise are given in the following pages.

There were 72 full-time and part-time permanent people. In addition, there were 40 guest researchers and research associates in residence during the

past year who collaborated with Division scientists.

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RESEARCH STAFF

Metallurgical Processing

Biancaniello, Francis

Boettinger, William J

Coriell, Sam R.

Handwerker, Carol A.

Hardy, Stephen C.

Manning, John R.

Ridder, Stephen D.

Schaefer, Robert J.

Voorhees, Peter W.

Group

S. o Inert gas atomization and metal powder

processing

o Special alloy and quasicrystal

preparation

o Melt-spinning rapid solidification

o High temperature alloys/ intermetallics

o Rapid solidification

o Relation of alloy microstructures to

processing conditions

o Modeling of solidification processes

o Interface stability

o Convection and alloy segregation

during solidification

o Interface studies

o Diffusion- induced grain boundary

migration

o Metal matrix composites

o Alloy coarsening

o Surface tension measurements

o Interface segregation

o Metallurgical processing

o Diffusion kinetics

o Interface migration

o Inert gas atomization

o Microparticle rapid solidification

o Solidification dynamics

o Solidification processes

o Quasicrystals/ intermetallics

o Electron beam rapid solidification

o Coarsening phenomena

o Elastic effects during phase

transformations

o Anisotropic interface effects

6
Corrosion and Wear Group

Anderson, David B. o Industrial corrosion testing

o Corrosion data evaluation

o Corrosion database development

o Expert systems for corrosion control

Bertocci, Ugo o Electrochemical measurements

o Computer modeling

o Passivity and pitting

Blau, Peter J. o Friction and wear transitions

o Wear microstructure relations

o Microindentation and scratch hardness

Escalante, Edward o Underground corrosion

o Corrosion in concrete

o Corrosion rate measurements

Fraker, Anna Co o Titanium alloys

o Corrosion processes

o Transmission electron microscopy

o Surgical implant metals

Hall, Dale E. o Electrochemistry

o Corrosion of advanced materials

Harris, Jonice S„ o Scanning electron microscopy

o Corrosion measurements

o Wear and friction properties

Harrison, Steven A. o Computer systems programming

o Software engineering

o Laboratory automation

Interrante, Charles G. o Hydrogen embrittlement

o Nuclear waste disposal

o Environmental testing

o Welding metallurgy

Ives, Lewis K. o Wear of materials

o Transmission electron microscopy

o Mechanical properties

Peterson, Marshall B. o Wear of materials

o Solid film lubricants

o Mechanical behavior

Polvani, Robert S. o Mechanical behavior

o High temperature strengthening

mechanisms

o Microindentation measurements

o Dimensional instability behavior

7
Ricker, Richard E. o Environmental induced fracture

o Scanning and transmission electron

microscopy

o Corrosion and electrochemistry

Ruff, Arthur W* o Wear and friction

o Microstructure effects

o Mechanical behavior

o Microscopy

Smith, John H. o Mechanical properties of materials

o Fracture of materials

o Structural integrity analysis

Stoudt, Mark R. o Physical metallurgy

o Corrosion engineering

o Environmentally induced fracture

Ugiansky, Gilbert M. o Management of computer database for

corrosion data

o Corrosion data evaluation and

dissemination

o Localized corrosion

o Slow strain rate stress corrosion

testing

Van Orden, Ann Co o Marine corrosion

o Localized corrosion

o Dealloying

Metallurgical Structure Group

Burton, Benjamin P. o Thermodynamic modeling of alloy phase

diagrams

o Order-disorder and phase separation in

alloy systems

o Associate editor, BAPD

o Computer database development

o Ab-initio calculation of phase

diagrams

Clark, J. Beverly o Precipitation processes in alloys

o Evaluation of magnesium-base binary

phase diagrams

o Editor, Bulletin of Alloy Phase

Diagrams

McAlister, Archie J. o Differential thermal analysis

o Equilibrium phase diagrams

o Enthalpy and kinetics of metastable

phase transformations

o Evaluation of binary and higher order

phase diagram data

8
Shapiro, Alexander J. o Analytical electron microscopy

o X-ray microanalysis

o Image analysis

o Transmission electron microscopy

Electrodeposition Group

Beauchamp, Carlos R. o Computer simulation of

electrodeposition processes on moving

fibers

o Electrochemical measurements of

kinetic parameters

Brown, Henrietta J. o Coating thickness SRM development

o Simultaneous thickness

electropotential (STEP) SRM

development

Claggett, Sandra W. o Scanning electron microscopy

o Metallographic specimen preparation

o General electroplating

Johnson, Christian E. o Ultra-black coatings

o Electroless deposition processes

o Metallic glass alloy deposition

o Microhardness SRM research

o Chromium deposition

o Pulsed alloy deposition

Kelley, David R. o Microhardness SRM development

o Dye penetrant SRM development

o Precious metal electrodeposition

o Plating on aluminum

Lashmore, David R» o Electrochemical mechanisms of coating

processes

o Pulsed alloy deposition

o Composition modulated alloy deposition

o Properties and structure of

electrodeposited coatings

o Amorphous alloys

o Transmission electron microscopes

o Metal matrix composites

Mullen, Jasper L. o Development of automated hardness

testing

o Electrochemical measurements for

determining metal corrosion

o Analytical spectroscopy

9
Stafford, Gery R. o Electrocatalysis

o Electrochemical transients

o Electrodeposition

o Molten salt electrochemistry

Nondestructive Characterization Group

Clough, Roger B. o Acoustic emission

o Mechanical properties

o Surface modification

Kahn, Arnold H. o Eddy current modeling

o Electromagnetic theory

o Solid state physics

Johnson, Ward L. o Ultrasonics

o Solid state physics

o Point defects in metals &

semiconductors

Linzer, Melvin o Ultrasonic imaging

o Acoustic emission

o Ultrasonic scattering

Mauer, Floyd A. o Ultrasonic tomography

o X-ray diffraction

o Ultrasound-microstructure relations

Norton, Stephen J. o Ultrasonic and NMR imaging

o Inverse modeling

o Mossbauer imaging

Pitchure, David J. o Digital electronics

o Ultrasonic instruments

o High temperature measurements

Simmons , John A. o Dislocation theory

o Acoustic emission

o Inverse modeling

Wadley

,

Haydn N.G. o Dislocations and fracture

o Acoustic emission

o Ultrasonics

10
Magnetic Materials Group

Bennett, Lawrence, H.

Shull, Robert D

Swart zendruber

,

Lydon J.

o Magnetic measurements

o Alloy phase stability

o Hyperfine fields

o Magnetic susceptibility

o Mossbauer effect

o X-ray and neutron diffraction

o Differential thermal analysis

o Scanning electron microscopy

o Magnetic susceptibility

o Magnetic methods, NDE

o Gamma-ray resonance spectroscopy

o Iron binary phase diagrams

11
.

'
METALLURGICAL PROCESSING John R. Manning

The properties of alloys depend on their processing history. Proper control

of processing conditions allows tailoring of alloys to produce

microstructures, compositions, and properties needed for particular

applications. The NBS work on metallurgical processing has as its objective

the development of measurements, measurement methods, and predictive models

to allow improved control of metallurgical processes. The resulting

guidelines, models, and control techniques then can be used to produce cost

savings, increased reliability, and higher performance in final products,

An important aspect of this effort is the establishment of strong

interactions with industry, universities, and other Government agencies.

During the past year a new NBS -industry consortium was formed to fund and

perform research on automated processing of rapidly solidified metal powders

produced by high pressure inert gas atomization. The objective of this

consortium work is to develop particle size measurement techniques that can provide immediate feedback to the atomization system, thus providing control

of powder size distributions while the powder is being produced. Initial

industrial participants in this consortium are Crucible Materials, General

Electric, and Hoeganaes.

In other interactions, collaboration continues with the steel industry on problems concerning continuous casting. In cases where NBS has special

processing facilities, these are made available to non-NBS scientists. For

example, visiting scientists from industry and universities come to NBS to

participate in the preparation of special rapidly solidified alloys.

Interface studies for application to metal matrix composites and studies of

stress effects on alloy coarsening are funded at NBS by the Office of Naval

Research. A new program on high temperature alloys and interme tallies is

being supported by the Defense Advanced Research Projects Agency. Work on powder processing of rapidly solidified alloys was funded during the past

year by the Naval Air Development Center. Measurements and modeling of

convection during directional solidification and of coarsening in liquidsolid mixtures are being sponsored by the National Aeronautics and Space

Administration.

The emphasis of the work is on (1) new science and technology, such as the

recently started work on interface processes in metal matrix composites and

on non-equilibrium processing paths for intermetallics ; (2) recently

discovered phenomena, such as quasicrystals and unexpected stress effects at

solid interfaces, both of which were discovered as a result of special

metallurgical processing work at NBS; and (3) measurements and predictive

models, such as in work on automated processing for atomization and in

controlled solidification studies.

FY 87 Significant Accomplishments

o Conditions were discovered which greatly increase the stability against

precipitate coarsening of precipitation- strengthened aluminum- iron-base

powder alloys. This stability depends on formation of phase sequences

involving an amorphous phase, similar to sequences previously

encountered in NBS quasicrystal studies. This result provides the

13
prospect that bulk parts can be made from these powder alloys without

loss of the useful properties imparted by their original rapid

solidification.

o Experiments were performed in which alternating deposition and

dissolution reactions were produced by diffusion-generated stresses and

other driving forces present at originally planar Mo(solid) -Ni( liquid)

interfaces. This result demonstrated the strong effect that stresses

produced by diffusion across interfaces, such as occur in metal matrix

composites, can have in destabilizing these interfaces.

o Effects of atomization conditions on average powder particle size in Sn

alloys were measured during test runs in the recently-commissioned NBS

high pressure inert gas atomization system. Typically, ten-pound powder

batches with average particle diameters as small as 20 micrometers were produced under known, controlled conditions. In addition, successful

powder production runs were made with Al-base and Cu-base alloys in this

system.

o Coarsening of solid particles in a Pb-Sn solid- liquid mixture was quantitatively measured at high volume fraction solid and shown to

follow the trend predicted by coarsening theories recently developed at

NBS. This work provided the first systematic experimental test of

precipitate coarsening theories for the high volume fraction regime.

o Growth patterns for Al-Li-Cu quasicrystals were analyzed and found to

have fastest growth along the five -fold icosahedral axes. This

contrasts with previous results on Al-Mn where the fastest growth was along the three -fold icosahedral axes.

o The conditions for the formation of various ordered phases by rapid

solidification in the NiAl-NiTi high temperature intermetallic system were determined. The B2 phase was found to form at some compositions

where the L2 X phase was stable, permitting the formation of special twophase microstructures important for high temperature creep properties.

This investigation required the use of the thermodynamics of second

order phase transformations.

Physical Metallurgy and Processing of Advanced Alloys

W. J. Boettinger, R. J. Schaefer, S. D. Ridder, S. R. Coriell,

F. S. Biancaniello , J. W. Cahn, L. A. Bendersky*, and D. Shechtman**

* Guest Scientist - Johns Hopkins University

** Guest Scientist - Johns Hopkins University and Technion, Haifa, Israel

The development of new alloys with improved strength, lower density, and/or

higher operating temperatures often proceeds by incremental modifications of

existing alloys. The research reported here, however, follows a somewhat

different approach, being more concerned with new processing methods and

classes of alloys not normally employed in conventional metallurgical

practice. These alloys and processing methods in many cases produce large

14
improvements over properties of conventional materials. Scientific

information developed in this work provides guidelines which can be used in

applying these new alloys and processes to specific product applications.

Rapid solidification followed by controlled thermomechanical processing is

being used to produce microstructures unobtainable by conventional casting

and forging. Focus on specific alloy systems, while necessary for

experimental research, is aimed at obtaining general strategies for alloy

processing and directing theoretical efforts to issues of technological

importance. New work has been initiated into the processing of alloys based

on intermetallic compounds. Also, ideas generated in the NBS studies of

quasicrystals have been applied to understand the phases formed in

precipitation-strengthened aluminum alloys.

Intermetallic High Temperature Alloys - Because of their high melting

temperatures and low densities, many intermetallic compounds show promise for

a generation of advanced alloys which may span the gap between ductile

metallic alloys and brittle ceramic materials. Recently the application of

rapid solidification and other new processing techniques to intermetallic

alloys has stimulated a renewed effort in the development of high temperature

intermetallics to replace Ni-base superalloys.

Research on intermetallic compounds is directed toward the examination of

processing paths involving metastable phases to produce new and unusual twophase structures. For example, the formation of ductile second phase

particles in intermetallics has the potential of increasing the toughness of

these materials. Since equilibrium phase diagrams suggest only limited

opportunities for precipitation from supersaturated intermetallic phases by

conventional heat treatment, the possibility of extending the range of

solubility of intermetallics by rapid solidification is being examined. The

possibility of quenching the related disordered form of intermetallic phases

is also of interest.

Research has been directed toward four alloy systems, Nb-Al, Nb-Si, Ti-Al,

and NiAl-NiTi. The intermetallic compound NbAl3 has a very limited

equilibrium range of composition (<1%) . Alloys which are ±3 atomic percent

from the stoichiometric compound were melt spun, but no increase in the range

of solubility was found. These preliminary results are being examined from a thermodynamic and kinetic viewpoint and future experiments are being planned

using laser surface melting. Research on the other three systems has been

published or accepted for publication. "Micros tructural Characterization of

Rapidly Solidified Nb-Si Alloys" presents interesting microstructures

containing fine grain (15-100 nm) mixtures of the intermetallic Nb 5 Si 3 and

BCC-Nb. The observed microstructures are shown to be consistent with a metastable phase diagram and T0 curves for the Nb-Si system. "Pathways for

Microstructural Development in TiAl," written jointly with J. Graves and

J. Perepezko of the University of Wisconsin at Madison, examines the

formation of a disordered HCP phase at the TiAl composition by rapid

solidification and subsequent ordering to the Ti3 Al structure during solid

state cooling as shown in figure 1. Further decomposition of this structure

during post solidification heat treatment into alternating plates of Ti 3 Al

and TiAl demonstrates the different microstructural paths possible with new processing methods. Finally in "Rapid Solidification and Ordering of B2 and

L2j_ Phases in the NiAl-NiTi System" evidence is presented for direct

15
solidification of the B2 phase at compositions where the L2 X phase is stable

at the liquidus. This extension of the range of homogeneity of the B2 phase

results in the formation of L2 1 precipitates in the B2 matrix after heat

treatment, with volume fractions not possible by conventional means. Interestingly, in this system the continuous ordering between the B2 and L2 X phase alters the precipitation process in a way which requires an examination

of the kinetics of second order phase transformations.

Theory of Microstructure Development - A major advantage of rapid

solidification is the increased alloy homogeneity that can be provided by

avoiding interdendritic segregation. In order to better understand what

conditions lead to the reduction of microsegregation during rapid

solidification, a complete theory of dendritic growth was formulated. This

theory predicts the dendrite growth velocity, tip radius, and composition as

a function of the undercooling below the equilibrium liquidus, which usually

occurs in rapid solidification processes. The theory includes corrections to

older theories necessary to treat high thermal and solute Peclet numbers

common for high growth rate and non-equilibrium interface conditions (solute

trapping) . The theory predicts a sharp change in dendrite composition and

radius as a function of undercooling as shown for a Ag-15wt% Cu alloy in

figure 2. This transition is related to the unique microstructures obtained

during rapid solidification.

Aluminum-base Alloys Involving Quasicrvstals and Related Phases - Aluminum

alloys containing large additions (-10%) of elements with limited equilibrium

solubility (<2%) form one of the new classes of alloys made possible by rapid

solidification. Instead of freezing with large brittle intermetallic phases,

these alloys can be processed to contain a fine dispersion (50 nm) of

intermetallic phase with resultant improvements in high temperature (340 °C)

performance due to the slow microstructural coarsening rate. Research has

focused on Al-Fe-Si alloys where the microstructural path from liquid to

powders to consolidated bulk material has been studied. While over 20 stable

and metastable ferrosilicide phases have been reported in the literature in

this system, rapidly solidified alloys contain only two phases in combination

with the primary aluminum phase: the first is a BCC phase designated a- (Al,Fe,Si) which is very resistant to coarsening in the aluminum matrix; the

second is an amorphous phase with extended short-range order. The

relationship between the structures of these two phases has been studied by

electron microscopy. The phases can be thought of as different packings of

Mackay icosahedra, which are the icosahedral units often used in models of

quasicrystal phases. During heat treatment and consolidation of powders the

relationship appears to control the nucleation of the BCC phase and thus is

directly related to the changes of the microstructure during consolidation.

Other activities involving structural studies of icosahedral quasicrystals

have involved Al-Mn and Al-Cu-Li alloys. Structural similarities between AlMn quasicrystals and a variety of stable and metastable Al-Mn intermetallic

crystalline phases determined using electron diffraction suggest that many of

these phases have a structural skeleton of icosahedral units arranged in

different stackings. Figure 3 shows a selected area diffraction pattern of

the hexagonal (crystalline) /i phase showing pseudo - icosahedral (5-fold)

symmetry which results from the oriented icosahedral units within the

hexagonal crystal. Dendritic crystals of the icosahedral Al 6 Li 3 Cu phase over

1 cm in length have been produced by directional solidification. It has been

16
found that these dendrites have a growth form which differs from that of

icosahedral Al-Mn as a result of preferred growth along the 5-fold instead of

the 3 -fold symmetry axis.

Powder Processing - Inert gas atomization is an important method for the

production of rapidly solidified alloy powders. A full scale high-pressure

inert gas atomization system has been constructed for the purpose of

providing powders of experimental alloys and of investigating and controlling

the atomization process to produce desired powder size distributions and

microstructures. A consortium of industrial companies, including Crucible

Materials, General Electric, and Hoeganaes, has joined in this research

effort. To date approximately 20 atomization runs have been performed on alloys with melting points up to 780 °C. In these runs, ten-pound batches of

Sn-base, Al-base, or Cu-base alloys have been atomized to produce rapidly

solidified powder with average particle diameters as small as 20 micrometers.

Modification of the atomizer to permit the installation of a variety of sensors has been completed. These modifications will permit photography of

the breakup of the molten metal stream by the high pressure atomizing gas and

on-line powder size measurement in the collection system by laser scattering

A schematic of the system is shown in figure 5. The powder size measurements

will eventually be used in a feedback control system. Preliminary studies of

particle size as a function of gas jet velocity and metal flow rate have

suggested that these parameters must be controlled independently.

Studies on the consolidation of powder by hot isostatic pressing (HIPing) are concerned with the microstructural coarsening of the Al-Fe-Si alloys

described previously and the development of sensors for real-time monitoring

of the density change during consolidation. This latter effort is being

performed in collaboration with the Nondestructive Characterization Group of

the Metallurgy Division and is described in detail in their section of this

annual report.

Controlled Solidification

S. R. Coriell, R. J. Schaefer, and J. R. Manning

In this research, the fluid flow, solute segregation, and interface

morphologies which occur during solidification are being studied and

techniques for monitoring solidification velocities are being developed. In

collaboration with G. B. McFadden and R. F. Boisvert of the NBS Center for

Applied Mathematics, R. F. Sekerka of Carnegie -Mellon University,

A. A. Wheeler of the University of Bristol, and D. T. J. Hurle of the Royal

Signals and Radar Establishment, convection and interface stability during

alloy solidification have been analyzed and modelled. The resulting

predictive models can be used to guide alloy designers in choosing processing

conditions that will provide optimum properties of the solidified materials,

for example, in providing homogeneous material needed for electronic

applications and in predicting the type of alloy segregation expected during

the continuous casting of steel.

Convection and Interface Morphology during Directional Solidification - During solidification of alloys from the melt, the crystal-melt interface is

subject to morphological instability. For directional solidification at

constant velocity, a planar crystal-melt interface is stable for sufficiently

17
low solute concentrations or for sufficiently high temperature gradients.

For typical temperature gradients and binary alloy compositions, the

interface is stable for low and high solidification velocities, but unstable

at intermediate velocities. The morphological stability theory has been

extended in current work to the directional solidification of multicomponent

alloys [J. Crystal Growth, 82

.

(1987), 295-302], It was found that

additional solutes enhance instability, but with different weighing factors

for each of the solutes. For example, in the Fe-C-S system, sulfur with its

low distribution coefficient is more effective in causing instability than

carbon with a relatively high distribution coefficient.

Three-dimensional steady-state solutions for nonplanar interface morphologies

have been computed numerically by using finite differences. A linear

temperature field was assumed, corresponding to the case of equal thermal

properties in the crystal and melt, with negligible latent heat release. The

solute field in the melt and the unknown crystal-melt interface position were obtained self -consistently . For an aluminum- chromium alloy with a distribution coefficient greater than one, steady state solutions

corresponding to two-dimensional bands and three-dimensional hexagonal nodes were obtained, as well as solutions with rectangular interface planforms.

For a small range of concentrations, there are two stable steady-state

solutions, the node solution and a rectangular solution. For the parameter

range of our calculations, two-dimensional and cell- like (rather than nodelike) solutions are not stable. These numerical calculations are consistent

with the results of weakly nonlinear theory. The weakly nonlinear theory is

being extended to allow for nonlinear temperature fields and the effects of

anisotropic surface tension. Additional numerical calculations are underway

for iron alloys, in particular, the iron- silicon system.

A possible technique for increased control of the directional freezing of

binary alloys is the passage of an electrical current through the system

comprising crystal and melt phases, and hence across the crystal-melt

interface. The passage of an electrical current results in electromigration

of the solute, and hence solute redistribution. Joule heating and

thermoelectric phenomena, such as the Peltier, Thompson, and Seebeck effects,

also occur. In addition, pulsed electrical currents are often used to

delineate the morphology of the crystal -melt interface in metals and

semiconductors. In order to provide a predictive basis for these techniques,

a theoretical study of the effect of electric currents on the solidification

process has been begun. A fully time -dependent linear stability analysis for

directional solidification of a binary alloy at constant velocity in the

presence of an electric field has been carried out. A modified

constitutional supercooling criterion for interface stability has been

obtained which is valid for a large range of conditions. Under certain

conditions, the onset of instability may be oscillatory in time.

Ultrasonic Measurements of Solidification and Crystal Growth in Metals and

Semiconductors - The velocity of sound and the density have values that are sufficiently different for liquid as compared to solid phases of metals,

alloys, and semiconductors to permit the use of pulse-echo ultrasonic

techniques to locate the solid- liquid interface during solidification,

crystal growth, and melting. This real-time ultrasonic metallography

technique was, in previous NBS work, clearly demonstrated for iron and

stainless steel samples. This method will be important to any materials

18
processing industry in which opaque materials are solidified, since real-time

measurements which allow feedback and control can provide both quality

control and productivity improvement.

Ultrasonic measurements have now been made on a number of specimens of

single-crystal alloy. Specimens were cut, machined, and polished to present

different crystallographic orientations to the ultrasonic waves. Both

velocity and attenuation measurements have been made. An x-y scanning test

bed has been constructed to permit quantitative measurement of echo strength

as a function of position on the test specimens.

These scanning tests showed very pronounced directionality effects in echo

strength at 5 MHz, at room temperature. For specimens with axial orientation

about 15° off the [001] axis, the attenuations in a 10 cm round-trip varied

by factors of more than 100 to 1, depending on position in these off-axis

specimens. In contrast, some very low attenuation values were obtained for

specimens along [001] and [010] as well as [110] axes. Further understanding

of these effects and their implications for solid- liquid interface monitoring

will require further testing of specimens at different orientations and at

elevated temperatures.

Solid State Processes and Alloy Interfaces

J. R. Manning, C. A. Handwerker, S. C. Hardy, P. W. Voorhees, J. W. Cahn,

J. D. Lee*, and W. H. Rhee**

* Guest Scientist - Chonnan National University, Kwangju, Korea

** Guest Scientist - Korea Advanced Institute of Science and Technology,

Seoul, Korea

Solid state reactions, especially those at interfaces, are critical in

determining the properties of a number of materials. Metal matrix

composites, surface modified alloys, and alloys undergoing coarsening are examples of materials where significant interface effects occur. Topics

that are important in current NBS work in this area include surface energy

effects and the effect of stresses generated near interfaces by diffusion

processes in solids. It has been found that these stresses and energies can produce surprisingly large deviations from equilibrium concentrations at

interfaces, enhance the stability of precipitation- strengthened alloys, and cause unexpected interface roughening.

Thermodynamics and Kinetics of Reactions at Non- Equilibrium Interfaces - At

non-equilibrium interfaces new phases can nucleate, diffusion can take place across and along the interface, stresses can be generated by lattice

mismatch, and complex dislocation reactions can occur. These processes can produce interface broadening, create interface roughness and dramatically

change the properties of the two-phase interface. Because of the practical

consequences of these interface reactions, principles governing these

processes need to be understood and their importance in controlling interface

properties evaluated. Metal matrix composites are prime examples of complex

engineering systems where materials are not in thermodynamic equilibrium

during initial fabrication, during production of components, or in use.

19
Resistance of these composites to fracture and crack propagation depends

strongly on the degree of bonding, the amount of fiber pull-out, and the

structure of the matrix- fiber interface.

Two major features of our current work on non -equilibrium interfaces are:

(1) the effect of surface energy variations on heterogeneous nucleation

textures, and (2) the effect of stresses produced by interdiffusion across an interface. A thermodynamic theory has been developed which demonstrates that

the orientations of crystals nucleating on a planar substrate should depend

on the equilibrium shape of the crystal and that minimizing the energy

barrier for nucleation leads to the predictions of strong orientation

textures that can change abruptly with small changes in the nucleation

conditions. For example, modifying the surface energies by small amounts,

such as by introducing alloying elements or by small changes in temperature,

could have strong effects on interface textures or roughness.

Diffusion at an interface generates large coherency stresses and strains when

the lattice parameter is a function of composition. At a solid-solid

interface the change in lattice parameter produces a compressive stress on

one side of the interface and a tensile stress on the other side, thus

creating a stress discontinuity at the interface. Current work shows that

the inclusion of this stress discontinuity into the thermodynamic and kinetic

equations for diffusion leads to a prediction that the interface compositions

and the diffusion profiles are shifted significantly from the unstressed

values. Experimental studies of this coherency stress effect are being

conducted on interdiffusion in Si-Ge multilayers using x-ray diffraction,

TEM. and atom-probe mass spectrometry techniques.

The effects of stresses generated by diffusion at liquid-solid interfaces

have also been demonstrated in experiments on Mo single crystals surrounded

by molten Ni. During diffusion of Ni into Mo, stresses due to atomic size

mismatch between Mo and Ni are generated in the diffusion zone. As a result

of these stresses, the originally planar interface between the solid Mo and

liquid Ni becomes unstable, forming a sinusoidal interface shape with a wavelength of approximately 5 x 10' 5 m, as shown in figure 4. As the

amplitude of the perturbation grows, precipitation of the equilibrium Mo-Ni

solid solution occurs at the peaks of the interface and dissolution in the

valleys. This dissolution-precipitation process produces significant

roughening of the interface. Similar interface roughening can occur during

fabrication of metal matrix composite materials which are often produced by

liquid metal infiltration into a fiber preform.

This interfacial instability is a newly identified phenomenon having broad

implications for micros tructural stability during processing and use of all

classes of materials containing a liquid phase. In particular, it is

important to understand how to suppress the instability when, for example,

planar composite interfaces are required for mechanical properties. In

conjunction with Professor Duk N. Yoon of the Korea Advanced Institute of

Science and Technology, NBS Metallurgy Division scientists are developing and

experimentally testing general predictive models for the interface morphology

changes in solid- liquid systems at elevated temperatures.

Diffusion- Induced Grain Boundary Migration - Grain boundaries in

polycrystals, when exposed to a solute source, have been found to migrate,

20
often away from their centers of curvature, and to form solid solutions in

the regions swept by the moving boundaries. Solute diffusion from the free

surface into the bulk has also been found to produce new grains of solid

solution alloy which nucleate in the original matrix grains in regions which

were essentially single crystals before exposure to the solute source. The

most important question which has been asked about these two processes is why

they occur at all; that is, what is the driving force which couples the

nucleation of new grains and the motion of the boundary to diffusion of the

solute. A mechanism map describing these phenomena has been derived which

contains various diffusion and migration regimes where different driving

forces dominate. The features of this map, which are qualitatively

consistent with results in Cu-Zn, are being examined in detail in several

materials systems.

Alloy Coarsening - Experiments have measured the coarsening kinetics of a two-phase mixture consisting of solid Pb-rich or Sn-rich particles in a eutectic liquid. These experiments are the first such coarsening experiments

using a system in which all the materials parameters necessary for a comparison between theory and experiment are known. The experimental scaled

particle radius distribution agrees quite well with the theoretically

predicted distribution. However, the mixtures are coarsening faster than

theory predicts. The cause of the apparent discrepancy in the predicted and

measured coarsening rates is currently being investigated.

In conjunction with B. Caroli, C. Caroli, and B. Roulet of the Groupe de

Physique des Solides of the University of Paris VII, the morphological

stability of a growing spherical particle from a melt including the effects

of compositionally generated elastic stresses was investigated. This is the

first study of the morphological stability of a solid- liquid interface to

employ the thermodynamics of stressed solids to determine the interfacial

equilibrium conditions. It was found that elastic stresses can either

destabilize or stabilize the growing particle. In some cases, the

compositionally generated stresses can destabilize the growing particle to

the extent that the critical radius for instability is decreased from 7 to 6 times the critical radius for nucleation.

21
Solid

Concentration

wt%

Cu

Figure 1. TEM dark field image of the hexagonal phase in melt spun

Ti-52 at % A1 using a superlattice reflection. The fine

antiphase domains prove that the ordering occurred in the solid

state and that metastable disordered hexagonal phase formed

originally from the melt.

Figure 2. Results of dendritic growth theory for Ag-15 wt% Cu which show

(a) the solid composition of the dendrite tip. and (b) the

dendrite tip radius for various undercoolings below the liquidus

22
Figure 3. Selected area electron diffraction pattern of the crystalline

hexagonal p-phase in Al-Mn showing pseudo-icosahedral 5-fold

symmetry.

Figure 4. Interfacial instability in Mo-Ni. Pure Mo single crystals and Ni were heated to 1450 °C for 10 min. The shades of grey indicate

a change in Ni concentration. Precipitation of the Ni saturated

solid solution occurs at the peaks of the instability and

dissolution occurs in the valleys.

23
24

Figure

5.

Schematic

of

high

pressure

inert

gas

atomization

system

showing

the

location

of

sensors
CORROSION AND WEAR Arthur W. Ruff

CORROSION

Corrosion is one of the major causes of the shortening of service life

of metallic structures. Corrosion is also a contributing factor in many

catastrophic failures with the consequent loss of life and property.

The cost of corrosion to the U.S. economy is estimated in excess of

$100 B/year. A significant fraction of this cost could be avoided by

better utilization of present knowledge and by new research findings.

The impact of corrosion is felt over a very wide range, from consumer

items such as automobiles to chemical plants and naval ships and planes.

In FY87 work was carried out in four main areas; 1) basic research on the mechanisms of corrosion, 2) development of corrosion measurement

techniques 3) dissemination of evaluated literature data on corrosion

and 4) studies of corrosion problems arising from the proposed disposal

of high level nuclear waste.

Stress corrosion cracking (SCC) has been the focus of the mechanisms

research during FY87. The cause of SCC is still poorly understood.

Critical experiments have been done this year to examine the several

different proposed mechanisms. Theoretical work has been conducted to

advance our understanding of electrochemical effects in SCC.

Extensive experience in the Group with corrosion measurement techniques

has been applied in the area of localized corrosion. Electrochemical noise

measurement techniques have been used to study corrosion pit initiation,

and statistical analysis methods have been developed. Studies are underway to determine the corrosion characteristics of a metallic glass

in both pitting and nonpitting environments.

The joint NACE-NBS Corrosion Data Center has seen considerable development

in this past year. The Center is serving as a central source of reliable,

evaluated corrosion data. Increasing cooperation with industry, other

organizations, and other countries has been seen this year. Two Industrial

Research Associates are now working with us at NBS in this effort.

Our assistance to the Nuclear Regulatory Commission on corrosion problems

associated with the disposal of high level nuclear waste has grown

considerably. This activity concerns a critical national problem with

specific timetables set by law. Metallic containers of highly radioactive

materials are proposed for burial at a geologic site to be selected and

are expected to withstand corrosion for at least 1000 years, well in excess of present industrial experience. Our work involves both information and data analysis, as well as critical laboratory measurements.

FY 87 Significant Accomplishments

o In the effort to model the electrochemical processes occurring inside

cracks which influence stress corrosion cracking (SCC), calculations

have been carried out to determine the range of values of the minimum

in electrode potential at the crack tip in the case of Cu-Au alloys in

25
in chloride solutions. The results have proved unequivocally that

hydrogen embrittlement cannot be the mechanism responsible for SCC in

these alloys.

o The NBS-NRC Data and Information Center has established a library for

corrosion, leaching, and high level waste package information as well

as a data base for storage and retrieval of NBS critical reviews and

pertinent information. The information contained there largely

involves review and evaluation of the DOE reports related to waste

packages being proposed for permanent storage of high-level

radioactive waste.

o The NACE-NBS Corrosion Data Center completed programming for software

products based on NACE corrosion data surveys for metals and

nonmetals in a wide variety of industrial environments. Joint

efforts with NACE and ASTM task groups have established guidelines

for standardization of corrosion data formats to facilitate

development of a complex evaluated database to serve as the basis for

additional distributed software addressing specific industry needs.

o Combined acoustic emission and stress corrosion cracking experiments

were performed on stainless steels (alloys 304, 310, 316 and 316

ELC) . Cracks were shown to advance with periodic bursts of acoustic

energy indicative of discontinuous propagation; the crack velocity

during advance was estimated as greater than 1 m/s.

o Electrochemical measurements combined with scanning electron

microscopy and energy dispersive x-ray analysis were used to

determine effects of saline solutions on the durability of heart

pacemaker leads consisting of a Co-Ni-Cr-Mo alloy in a polyurethane

sheath

.

o The role of grain boundary precipitate size distribution in the

intergranular stress corrosion cracking of Al-Li and Al-Li-Cu alloys was evaluated by conducting slow strain rate tests on samples with

reverted or resolutionized matrix precipitates. These experiments

show that it is the grain boundary precipitate size distribution, not

the matrix slip character, that is responsible for the beneficial

effect of heat treatment on the stress corrosion resistance of these

alloys

.

Mechanisms of Stress Corrosion Cracking

E.N. Pugh, U. Bertocci, R. Ricker, R. Rothea*, M. Stoudt, and J. Fink

* Guest Scientist, Rhone Poulenc, Inc . /University of Lyon, France

Mathematical modeling of the electrochemical and transport processes

inside a crack has been extended to the case of Au-Cu alloys, which

undergo transgranular stress corrosion cracking (TSCC) which is

morphologically identical to cracking in brass. The calculations have

shown that during cracking in Fe Cl 3 solutions the anodic reactions at the

crack tip (fig. 1) are likely to be the reduction of Fe+++ and of Cu++

, both mainly present as chloride complexes. In order to estimate the range

of potentials to be expected at the crack tip at the instant of crack

26
advance, reliable kinetic data for the redox reactions Fe+++ /Fe++ and

Cu++ /Cu+ on gold surfaces were necessary.

Potentiodynamic scans and a.c. impedance spectra carried out in solutions

similar to those present in the crack have provided the necessary values

for completing the mathematical modeling. The results show that hydrogen

cannot possibly be discharged inside the crack, and therefore hydrogen

embrittlement cannot be the cause of brittle fracture in these alloys.

Stress corrosion cracking (SCC) experiments were performed on single

crystals of pure copper in sodium acetate and sodium nitrate solutions.

The objective of these experiments was to evaluate the hypothesis that

surface oxide films can induce cleavage crack propagation and are responsible for transgranular SCC. Slow- strain-rate tests were conducted

in solutions of varying pH at constant electrode potentials. These

experiments were coupled with cyclic voltammetry and ellipsometry

experiments in the same solutions to evaluate the surface oxides present

and their stability at each potential. For both types of solutions,

susceptibility to transgranular cracking was found in potential ranges

where an oxide is stable and no cracking was found if an oxide film was not present (fig. 2). While an oxide film may be required for transgranular SCC (TSCC) , the presence of a film alone may not be sufficient to

induce TSCC. However, it is evident from both cyclic voltammetry and the

ellipsometry that the oxides behave differently in the two solutions and

that the characteristics of the film other than just its rate of growth

are important in determining the susceptibility to TSCC. Clearly, further

work is needed to establish the nature of the oxides and to evaluate the

role of the oxide properties in inducing stress corrosion cracking.

Combined acoustic emission and stress corrosion cracking experiments were performed on stainless steels (alloys 304, 310, 316 and 316 ELC) to

examine the discontinuous nature of TSCC, to evaluate the potential of

acoustic emission as a technique for detecting and monitoring stress

corrosion cracking propagation and to estimate the maximum velocity of

crack propagation during the discontinuous advance. Stress corrosion

cracks were shown to advance with periodic bursts of acoustic energy

indicative of discontinuous propagation. The observed signals were unique

to SCC propagation making it possible to monitor or detect SCC propagation. The crack velocity during advance was estimated as greater than

1 m/s. These results confirm the hypothesis that stress corrosion cracks

propagate in a discontinuous fashion consistent with the film induced

cleavage mechanism of stress corrosion cracking.

The role of grain boundary precipitate size distribution in the

intergranular stress corrosion cracking of Al-Li and Al-Li-Cu alloys was evaluated by conducting slow-strain_ rate tests on samples with reverted

or resolutionized matrix precipitates. This heat treatment allowed the

precipitate size distribution at the grain boundary to be varied while

maintaining the matrix precipitate size distribution and mechanical

properties essentially constant. These experiments show that, it is the

grain boundary precipitate size distribution and not the matrix slip

character that is responsible for the beneficial effect of heat treatment

on the stress corrosion resistance of these alloys.

27
Corrosion Measurement Methods

U. Bertocci, D. E. Hall, G. S. Stafford

The work on the statistics of corrosion pitting has continued with the

development of the statistical analysis of the current fluctuations

preceding pit initiation. In the part of the program pursued in

cooperation with the University of Manchester in the United Kingdom,

data concerning pit distribution on carbon steel plates are being

collected. Methods to analyze the results, based on extreme -value

statistics, are being developed.

Corrosion of Al-Mn metallic glass coatings has been studied in both

pitting (chloride) and nonpitting (sulfate) environments. The alloys,

with manganese contents ranging from about 10 to 30 percent by weight, were electrodeposited from a molten salt bath by the NBS Electrodeposition

Group. Limited corrosion data in the literature suggested that the alloys

might be superior to pure Al in some environments. Our research to date

has determined the corrosion characteristics in both pitting and non- pitting environments. The most noteworthy result is the difference in

pitting behavior between the alloys and either pure aluminum or electro

deposited aluminum. The onset of pitting for the alloys is roughly 400 mV more positive than that for aluminum. Furthermore, the pits which form in

the alloy coating are shallower than those in aluminum. These results

suggest that Al-Mn coatings may offer a high degree of corrosion protection to underlying base metals.

Corrosion Data Center

D. B. Anderson, C. D. Flanigan, T. Flax, P. Karras*, G. M. Ugiansky, and

E. D. Verink**

* Research Associate, NACE

** IPA, University of Florida

The NACE-NBS Corrosion Data Center continues as a focal point for computerization of corrosion data to characterize corrosion performance of

engineering materials over a wide variety of environments and exposure

conditions. Activities during 1987 centered on (1) programming software

based on NACE surveys for both metals and nonmetals and the NACE

Recommended Practice for assessing economic aspects of materials selection

for corrosion environments, (2) acquisition of existing industrial

corrosion data, (3) developing a database structure to facilitate capture

of multi-source corrosion data in formats compatible with defined user

needs and (4) with assistance from the Center for Applied Mathematics,

developing PC software utilizing the stability diagram programs originally

created at the University of Florida to study corrosion thermodynamics.

Programming of the NACE survey data has been completed and resulting PC

software is being marketed by NACE as CORSUR Corrosion Data Software. The

programs permit material compatibility searching for user defined

environmental conditions (fig. 3) which greatly enhances the usefulness

of the base data. Programming has also been completed for the companion

economics software for NACE distribution during FY88, The complex

28
stability diagram programming is continuing.

Working in conjunction with task groups within NACE and ASTM, basic

guidelines have been established for standards development in the

important area of corrosion data formatting. This will facilitate data

recording and capture in standard formats compatible with database

management needs and other material property database developments. These

formats are serving as the basis for a database structure used to compile

numeric data from existing industrial sources and facilitate distributed

outputs targeted towards specific environments and applications.

Recognizing the complexities of corrosion data interpretation for

materials selection in key chemical environments, the Materials Technology

Institute of the Chemical and Process Industries (MTI) has initiated a contract with NACE which has resulted in the establishment of a new three

year Research Associate program in the Data Center to exploit growing

interest in expert system technology.

Nuclear Waste Packaging Materials

C. G. Interrante , D. Anderson, U. Bertocci, P. Boyer, I. Coyle,

E. Escalante, A. Fraker, D. Hall, J. Harris, S„ Harrison, W. Liggett,

M. Linzer, H. Ondik, E. Plante, E. N. Pugh, R. Ricker, A. W. Ruff,

J. Ruspi, A. Sembira*, R. D. Shull, M. Stoudt

* Guest Scientist, Atomic Energy Commission, Israel

In a program titled "Evaluation and Compilation of DOE Waste Package Test

Data," initiated in FY85, the NBS supports the High Level Waste (HLW)

Management Program of Nuclear Regulatory Commission (NRC) . The NBS

assists the NRC by evaluating the Department of Energy's activities on high level waste disposal. These waste packages are being designed for use in a permanent repository for the disposal of radioactive waste from

nuclear power plants and other sources. Potential problems threatening

the integrity of a waste package include pitting, stress corrosion

cracking, and hydrogen embrittlement. These problem areas are the main

thrust of the Metallurgy Division's effort in addition to program

management. Another area of concern is leaching of borosilicate glass,

and this effort is carried out in part by members of the Ceramics

Division. The program is also supported by statistical and modeling

specialists from the Center for Applied Mathematics, as well as by six

consultants from outside NBS. During this year, an HLW Data Center was established at NBS. The collection includes over 500 papers and technical

reports. A computerized data base was created and implemented to provide

access to these materials. The data base includes the full text of all

technical reviews completed and in-progress.

Various forms of technical assistance are rendered to the NRC. The work

involves conducting formal reviews -- over 40 were completed in FY87 for

publication -- of the research and development efforts of the DOE Waste

Package Program, technical review of other related documents (NRC, DOE

and their contractors ) interaction with the international technical

community and general review of all relevant present and planned

activities of the DOE. These include expected modes of degradation,

evaluation of various other failure modes, test methods, design of

29
experiments, theoretical and modeling efforts, and laboratory testing.

An important objective is to identify additional data and types of tests

needed to demonstrate that the DOE waste package designs will meet NRC's

performance objectives. At the NBS , laboratory testing is conducted to

confirm the accuracy of DOE data and the validity of the conclusions

deduced from it. This year laboratory studies were initiated in the

Division in four areas, as follows: (1) Evaluation of Methods for

Detection of Stress Corrosion Crack Propagation in Fracture Mechanics

Samples, (2) Effect of Resistivity and Transport on Corrosion of Waste

Package Materials, (3) Pitting Corrosion of Steel Used for Nuclear Waste

Storage, and (4) Corrosion Behavior of Zircaloy Nuclear Fuel Cladding.

Surgical Implant Metals

A. C. Fraker and J. S. Harris

Metals and alloys that were studied this year included those used as heart pacemaker leads and used for orthopedic devices . The laboratory

investigations involved corrosion, microstructures, alloy composition

and mechanical properties. Other efforts in this task included numerous

interactions with surgical implant manufacturers and participation in

the American Society for Testing and Materials F-4 Committee on Medical

and Surgical Materials and Devices.

Heart Pacemaker Leads - This was a cooperative study with the Food and

Drug Administration (FDA) . A Co-Ni-Cr-Mo wire lead in a polyurethane

sheath or tube was exposed to simulated body fluids for 14 months.

Failures have been observed due to the degradation and leakage of the

polyurethane insulating material. Mechanisms of the polyurethane

degradation and reactions of the Co-Ni-Cr-Mo wire use have not been

established. Our tests were conducted to determine if the polyurethane

did actually leak and what the effects were on the wire and the

polyurethane. After exposure of the shielded lead in simulated body fluid

at voltages varying from 5 volts to 20 volts, it was evident that leakage

had occurred in a number of sites in the polyurethane. Scanning electron

microscopy and energy dispersive x-ray analysis (fig. 4) showed that the

metal had corroded at these sites and metal corrosion products were on the

inner surface of the polyurethane. Small angle x-ray scattering

measurements indicated that metal ions diffuse preferentially through the

soft segment of the polyurethane.

Alloys for Orthopedic Devices - Materials studied include 316L stainless

steel, Co-Cr-Mo, Ti-6Al-4V and Co-Ni-Cr-Mo. Other materials proposed for

surgical implant use such as nitrogen- strengthened stainless steel, beta

titanium alloys and the Ti-5Al-2.5Fe are studied for comparison.

Corrosion, repassivation kinetics, pitting and corrosion- fatigue behavior

of these materials in simulated body fluids are studied. Previous data

from this project showed comparisons of fatigue strength of the various

orthopedic materials and effects of processing and surface treatment on corrosion- fatigue . Current emphasis is on the Ti-5Al-2.5Fe alloy, beta

titanium alloys, and nitrogen- strengthened stainless steel. Work involves

relating microstructures and mechanical properties of Ti-6Al-4V to

variations in composition (especially oxygen) and heat treatment. This is

a cooperative study with the Zimmer implant manufacturing company.

30
WEAR

Measurements of wear and friction properties are carried out to

(1) improve understanding of fundamental physical and chemical mechanisms,

(2) to develop better quantitative measurement methods, and (3) to develop

standards and reference materials. Experimental methods used include wear

testing, optical and electron microscopy, microindentation measurements,

metallography, surface microanalysis, and wear particle analysis.

Analytical modeling is done of break-in effects in friction and wear.

Costs associated with wear failure and inadequate tribological performance

have a significant economic effect in the U.S. and the world. Estimated

costs of wear are about $50 B/year in the U.S. Greater use of more wear-resistant materials (and data on existing materials) can improve

industrial productivity and our competitive position world-wide. This

task is developing test methods and evaluating new materials having

improved wear properties. Data obtained on such materials may be used

then by design engineers in new applications. One area of emphasis in this

task is that of wear data for commercially important alloys and coatings,

both existing and new.

The program is supported in part by other Federal agencies in recognition

of the importance of adequate wear behavior of machinery and mechanical

systems. The Department of Energy (DOE) supports our work in galling wear

of materials where new measurement methods for quantitatively assessing

galling performance have been developed. New industrial valve materials

and coatings have been examined in this work. The Office of Naval

Research supports a research project on the mechanisms of wear in

engineered metallic coatings having unique microstructure.

Several activities in the Group have direct involvement with private

industry. We are conducting joint measurements with Deere and Company,

Moline, IL, on galling wear properties of materials. A Research Associate

from the company is investigating problems connected with the measurement

of galling damage and the development of tests to determine the galling

behavior of metals. In another project, a Research Associate is

conducting wear measurements at our laboratory involving a hybrid liquidsolid lubricant that can be used with sliding metal surfaces at elevated

temperatures. In addition, our wear data evaluation and compilation

efforts are done in conjunction with several private companies and

universities

.

FY 87 Significant Accomplishments

o Abrasive wear coefficients have been evaluated for a group of

frequently used metals under standard wear test conditions, and

assembled into a data base for use in a new, PC-based, tribology

data and information system (ACTIS) being developed under the

sponsorship of several federal agencies and professional societies.

o A new type of hybrid, liquid- solid , lubricating material has been

produced and studied under elevated temperature sliding wear

31
conditions; it was found to offer significant protection to steel

surfaces. The concept involved should be extendable to a broad range

of other materials and wear conditions. This work was conducted

jointly with a Research Associate.

o Wear and friction behavior of electrodeposited, composition-modulated

nickel-copper coatings on steel have been measured under both

lubricated and unlubricated sliding conditions and found to offer

significant improvement over the pure metals. The basis is believed

to lie in the unique microstructure of the coatings which are produced

at NBS in the Electrodeposition Group.

o The galling behavior of nitrated steels was investigated and showed

that surface nitrating significantly increased galling resistance.

Galling severity measurements used an NBS developed method based on surface topographic parameters. This work was conducted jointly with

a Research Associate.

o Studies have verified that undesirable time-dependent sustained slow

cracking occurs in seamless aluminum cylinders made of alloy 6351 and

used for gas storage and air-breathing applications. Modifications to

the processes for producing these cylinders have been made to reduce

the significance of this cracking.

Mechanisms of Galling Wear

L. K. Ives, M. B. Peterson, E. Whitenton and P. Swanson*

* Research Associate, Deere and Co.

A project on the galling wear of metals is partially sponsored by the

Department of Energy. Galling is a form of wear which occurs on sliding

surfaces leaving them severely damaged due to plastic deformation,

fracture, and metal transfer. It usually occurs in poorly lubricated or heavily loaded components such as valves, threaded connections, structural

joints, or bushings. Our approach has been to study the influence of

various metallurgical parameters on galling severity, where galling

severity is a measured quantity based on surface topography such as displaced volume or average maximum peak to valley roughness.

Recent work has been concerned with the development of models for the

galling process. An extensive literature search was undertaken to

supplement experimental data on galling obtained in the program. It was concluded that galling is basically a shear fracture process with

fracture beginning at the rear of a local contact area. The severity

of the galling damage is determined by the deformation process which

precedes fracture. Some important factors influencing galling severity

are crystal structure, stacking fault energy, and the available slip

systems. Surface roughness can also have a significant effect on galling severity. Adhesion is important in that it influences the

contact stresses. With high adhesion large prows may form increasing

the extent of the damage which occurs.

Galling damage in a variety of commercial alloys has been studied. As

shown in figure 5, hardness does not correlate with damage severity among the

32
metals tested. Also, stainless steels, as a group, do not behave more poorly than other metals as has sometimes been stated. It may be noted

that Nitronic 60, which is an austenitic stainless steel, shows little

damage. Our studies have indicated that this behavior is a result of the

low stacking fault energy of this alloy. The damage to leaded brass is

also low. This is attributed to the presence of a thin film of lead that

is smeared over the surface during sliding which acts as a lubricant.

Wear Properties of Metal Coatings

A. W. Ruff, E. Whitenton, J. Robbins, and N. K. Myshkin*

* Guest Scientist, U.S.S.R

A study has been completed of the lubricated wear behavior of electrodeposited composition-modulated nickel-copper alloys having two different

layer spacings, 10 nm and 100 run, under lubricated sliding conditions

against type 52100 bearing steel. The alloys were prepared as coatings

about 20 thick on steel cylinders. A standard crossed-cylinder wear

test geometry was used. Three liquids were used: pure paraffin oil both

with and without the addition of oleic acid, and a solution of 0.6

glycerine and 0.4 ethanol. Electrical measurements of the contact

resistance were made to assist in interpretation of the nature of the

boundary lubrication film present during sliding. Wear data and friction

coefficient values were obtained. The lubricated wear behavior of the two

composition-modulated Ni-Cu coatings differed considerably from that of

the two pure deposit coatings of Ni and Cu. The two Ni-Cu coatings

generally showed less wear, and the coating with the smaller laminar

spacing, 10 nm, showed the least wear. Among the three lubricants

examined, the Ni-Cu coatings showed the least wear with the 0.6 glycerin0.4 ethanol mixture. Somewhat greater wear occurred in paraffin oil, and

greater still when oleic acid was added. The pure deposits of Ni and Cu

showed greater wear than the alloys and responded differently in the three

fluid media. Friction coefficients were nearly the same in all the media.

Contact film voltage measurements showed that the Ni-Cu coatings had very

low values relative to steel, and to the copper and the nickel coatings.

This was interpreted to show a thinner film in the contact for the Ni-Cu

coatings, but a more durable one. The Ni-Cu coatings may be suitable

for use in current collection in view of their low wear and low contact

resistance

Mechanisms of Solid Lubrication

M. Peterson, L. K. Ives, A. W. Ruff, L. Fehrenbacker** , and J. Macia*'*

** Research Associates, TA&T, Inc.

Recent experiments in our laboratory have shown that it is possible to

develop a hybrid solid- liquid lubricant with improved performance for

possible use in high- temperature friction and wear environments. Using

our high- temperature sliding wear test system, studies were conducted on various combinations of synthetic lubricants with liquid and dry powder

additives. The formulations consisted of nickel and chromium intercalated

graphites at concentrations of about one-weight percent in the liquid

33
carriers. Tests were performed up to 250° C under highly loaded boundary

lubrication conditions. Further studies also indicated that solid

composites of metal or ceramics with these intercalated graphites may have

desirable wear and friction characteristics for such applications as ring- - liner combinations in high- temperature engines.

Friction and Wear Break-in

P. J. Blau and E. Whitenton

Studies of the mechanisms of break-in and other tribological transitions

in metals and alloys have resulted in the development of a framework

for a semi-empirical friction model of these processes. Provision for

incorporating parameters of the test geometry (including surface roughness), materials and microstructural properties, state of lubrication,

chemical and thermal environment, and mechanical test conditions has been

made, although terms for all these effects have not been completely

developed. Preliminary application of the model to unlubricated sliding

break-in tests (on Cu-15 wt%Ag) and polishing abrasive sliding tests

(52100 steel, 2014-T4 aluminum, was successful in portraying the cycle

number- dependence of the friction coefficient. The model was favorably

received at the 1986 ASME/ASLE fall meeting (Pittsburgh, PA), and has been

published. Work on the analytical model to incorporate existing wear

damage theories for known mechanisms of wear, and to develop terms for

transition incubation times under various thermal and applied load

conditions will be continued.

Wear Data and Standards

A. W. Ruff, M. B. Peterson, J. Harris, and J. Robbins

As part of the first coordinated attempt in the United States to gather

and evaluate important data about friction, lubrication, and wear between

materials, the initial phase of a project on abrasive wear has been

completed. With support from the Department of Energy, the principal

sponsor on the project, the American Society of Mechanical Engineers and

the American Society of Lubrication Engineers, data have been gathered and

evaluated about how materials hold up under different conditions of

abrasive wear (fig. 6). The data are entered into a personal computer

system for easy access and updating. Discussions have been held with

interested industrial organizations on the best way to share the database,

which is limited at this stage to selected materials. One possibility is an expansion of NBS- industry collaborations through the Research Associate

Program. In many industrial operations, the wear of machine components

and materials is one of the key factors in determining the service life

and down-time of equipment. Data on how materials wear while in operation

helps equipment and process designers as well as plant operators make the

most of their capital equipment investments and increase productivity.

Staff members continue to participate in the wear standardization work of

the ASTM G-2 Committee on Wear and Erosion. Chairmanship is held of the

Operations subcommittee, the Task Group on solid particle jet erosion

testing, and the Task Group on pin-on-disk testing. In the latter Group,

a draft standard has been written that will be the first such U.S.

34
standard. It is partly based on an international measurement effort that was formed under VAMAS . Major contributions are also made in the task

groups on galling wear, on crossed cylinder wear testing, and on friction

measurements. Several future symposia and workshops are being planned.

There are about 80 members of the Committee from private industry, so there is ample opportunity for the NBS staff to interact in an effective

manner

.

Mechanical Properties of Pressure Vessels

J. H. Smith and P. A. Boyer

Research is carried out under sponsorship of the Department of

Transportation Office of Hazardous Materials to establish a sound,

technical basis for safety standards governing the safe design,

manufacture, and use of seamless pressure vessels (cylinders) for the

storage and transportation of compressed gases. This research includes

the technical evaluation of proposed changes to the existing safety

regulations, development of new or improved test methods for selecting

materials, development of improved methods for the testing and inspection

and failure analysis to determine the cause of failures in cylinders.

Research has continued to develop design criteria for the construction of

high strength seamless steel cylinders. The objective of this work is to

develop suitable criteria to prevent failure of high strength cylinders by

fracture or by stress corrosion. Cooperative tests programs with Union

Carbide Corp . , T.I. Chesterfield Ltd., and N.I. Industries are being

conducted to establish a fracture criteria for steel cylinders. Extensive

full scale testing of preflawed cylinders and fracture toughness testing

has been conducted. A minimum fracture toughness, in terms of JIc, has

been established for the production of a limited size range of cylinders.

Research is continuing to extend the size range of cylinders to which this

fracture criteria can be applied. In addition tests are being conducted

to establish a fracture criteria that more accurately predicts the

fracture behavior of thin walled, ductile steel cylinders. An improved

test procedure based on the use of pneumatic burst testing of preflawed

cylinders for use as a quality control test during production is currently

being developed. Analysis of existing data on the stress corrosion

susceptibility of high strength steels is being performed to establish a maximum limit of the strength of high strength steel cylinders to preclude

failure by stress corrosion cracking.

A unique form of intergranular cracking has been found in the neck and

thread area of type 3A1 aluminum and fiberglass wrapped aluminum

cylinders. An ongoing investigation to determine the extent and cause of

this cracking is being conducted in cooperation with Luxfer USA Inc. and

Alcan Ltd. An example of the cracking that has been found is shown in

figure 7. In a few cases, cracking has propagated through the neck and

caused leaking. Investigations at NBS in the past year have confirmed

that this cracking occurs in all sizes and classes of aluminum cylinders

made from type 6351 alloy. This has resulted in a recall from service of

certain groups of these cylinders. Modifications of the alloy composition

and manufacturing process have been made to reduce the tendency for this

35
form of cracking. Results of tests on cylinders made from the modified

alloys and manufacturing processes are currently being investigated.

Research is being conducted on developing a method of using a combination

of acoustic emission and ultrasonic testing for the periodic reinspection

of large seamless steel cylinders used for transporting compressed gases.

Extensive testing of full sized cylinders using this method has been

conducted by the Linde Division of Union Carbide Corp. and by Fiba Inc.

Recent testing has demonstrated that this test method can reliably detect

most of the types of defects that occur in compressed gas cylinders during

normal service. A preliminary standard test procedure has been developed

for the use of this test method.

Micromechanical Properties Measurements

R. S. Polvani, A. W. Ruff, and J. C. Robbins

The NBS Dynamic Microindentation system has been used to make measurements

on an energetic material, crystals of RDX, to determine the effect of load

and loading time on their mechanical response. A spherical indenter tip was used. The results have been compared to those obtained earlier using

pyramidal Vickers indenters. At the shortest loading periods with a spherical indenter, a higher than expected plastic response was found;

this may indicate that local heating resulted from the indentation

process. The pyramidal indenter generally produced a different response,

probably due to its stress concentration effects (fig. 8). As a result of

this work two important mechanical characteristics of RDX have been

recognized. The first involves the importance of indenter geometry. At

high loading rates, the plastic behavior of RDX depends on the stress

concentration effect of the indenter geometry. It appears that RDX is not

inherently brittle as has been reported. Irrespective of the loading rate,

RDX was found to deform plastically for loadings up to 2 N using a ball

indenter. The second characteristic was that RDX became more ductile under

conditions of rapid indentation, in time intervals of 1 ms. This may have

resulted from local heating of critical regions in the RDX crystals, thus

affecting dislocation motion and interaction. A model of dynamic

mechanical behavior of energetic materials has been developed in this work

in collaboration with the University of Maryland.

36
minmV

NHE

LOG X 0 CCu/Cu~5. A/cm2

Figure 1. Calculated minimum electrode potential reached at the crack

tip during TSCC of Cu-Au alloy for

various exchange current densities.

Figure 2. Results from slow

strain rate tests of pure

copper monocrystals in 0 .

1

sodium acetate (pH = 5.5).

Zircon ium

F

500

- 400

300

20@

100

0

I <0.05 B <0.5 © 0. 5=1 . 3 1 >1.3 mm/y

2000 r

Energy (keV)

Figure 3. Computer- generated display

corrosion rates of zirconium as a function of concentration and temperature in aerated phosphoric acid.

Figure 4. EDX analysis of

corrodes heart pacemaker wire,

alloy Co-Ni-Cr-Mo, showing

increased amounts of Cr and Mo.

37
sevEnrrr.

m

(m)

Figure 5. Effect of material

hardness on galling severity.

Figure 7. Extent of cracking

in aluminum cylinder neck.

Dry Sond Rubber Wheel Wear Coef—AVERAGE

MATERIALS AVG OSH WHgMed AVG

Figure 6 . Average values for

abrasive wear coefficient using

ASTM standard method, as contained

in Tribology Data Base.

Log Vlch«n Otogonol Length (mm)

Figure 8. Pyramidal indentation

of RDX crystal shows transition

from plasticity to fracture at

0.3 N load.

38
METALLURGICAL STRUCTURE J. Beverley Clark

The principal activity of this group is the collaborative effort with the

American Society for Metals (ASM) in the joint ASM-NBS Alloy Phase Diagram Data

Center. This program continues to provide critically evaluated phase diagrams

and other constitutional data as well as related bibliographic material. ASM

provides overall program guidance, bibliographic support, and dissemination of

program outputs. NBS provides overall technical guidance to insure the data

reliability and accuracy of the evaluated phase diagrams, development of a model evaluation procedure and style guide by the two binary category editors

(magnesium, aluminum) located within the group for use by the other binary

category editors, and the development of a prototype database for on-line

retrieval of the phase diagram related data. The program has a strong

international content through the alloy category editors who are responsible

for the selection and evaluation of the data. Currently, there are thirty

binary and twenty ternary category editors participating in this program.

During the past year, the three NBS category editors completed evaluations of

fifteen magnesium, four aluminum, and one iron system. The magnesium binary

alloy systems have now been completed and are being compiled for publication as an ASM Monograph.

A new two volume compendium "Binary Alloy Phase Diagrams" has been published by

ASM. The compendium updating the compilations of Hansen, Elliot and Shunk

contains 1578 phase diagrams that were selected and digitized by the program at

NBS. The interactive relational phase diagram database has been loaded with

binary graphics, the numerical and crystal data of nearly 1600 binary phase

diagrams

.

The evaluation program has been extended to ternary diagrams with the initial

evaluation of Al-Cu-X ternary diagrams. New optimization programs have been

implemented for the calculation of ternary diagrams from thermodynamics and the

boundary binary phase diagrams.

In phase stability studies of amorphous Al-Mn alloys (16 to 40 wt% Mn) produced

by electrochemical deposition, return to the equilibrium structure occurs without the complex series of intermediate transformations seen in splat

quenched Al-Mn alloys.

The analytical capabilities of the JSM-840 Scanning Electron Microscope has

been greatly increased with the addition of a wavelength dispersive

spectrometer and ancillary X-ray and image analysis.

FY87 SIGNIFICANT ACCOMPLISHMENTS

o A relational database of the critical phase diagram data of nearly 1600

binary phase diagrams is ready for on-line search. The graphical and

numerical data of these phase diagrams and the crystal data of the

approximately 9000 phases in these phase diagrams are accessed readily by an easy data search program.

o Evaluations of ternary Al-Cu-X systems were initiated. The Al-Cu-Pb, and

Al-Cu-Bi systems are completed.

39
o A compilation of 1578 updated binary phase diagrams with corresponding

crystal structure data of the phases of each diagram was completed. A

two volume compendium of these binary phase diagrams and the ancillary

crystal structure data was published by ASM INTERNATIONAL.

Alloy Phase Diagram Data Center Activities

B. P. Burton, J. B. Clark, R. V. Drew, R. M. Hayes, L. F. Lilly*, A. J.

McAlister, C. E. S irofchuck* , and U. R. Kattner**

* American Society for Metals Research Associate

**Guest Scientist

All activities revolve about a collaborative data evaluation program for alloy

phase diagrams with the American Society for Metals (ASM INTERNATIONAL)

.

During the last year, the Alloy Phase Diagram Data Center has continued to be

the focal point for the entire ASM/NBS Phase Diagram Program.

Phase diagram evaluation projects are being carried out by three category

editors at NBS , J. B. Clark for magnesium alloys, A. J. McAlister for binary

aluminum alloys, and L. J. Swartzendruber for iron alloys. Coverage of the

systems includes crystal structure, metastable and constrained equilibria, and

high temperature thermodynamic properties as well as the stable equilibrium

diagrams. Calculations of the phase diagram from thermodynamic data are carried out using a number of computer programs available at NBS. The data

center staff are responsible for selection of reviewers for evaluations

submitted to the Bulletin of Alloy Phase Diagrams, technical editing of

evaluations and graphics digitization of submitted evaluated phase diagrams.

The Bulletin of Alloy Phase Diagrams continues to be published at the rate of

six issues per year. Technical editing is done by the editor, J. B. Clark.

Over 250 evaluations were technically edited for the Bulletin, and the Gold and

Beryllium Monographs. C. E. Sirofchuck supervises the computer entry of the

graphical and crystal data. Approximately, 700 binary phase diagrams were prepared for the above publications.

The relational binary phase diagram database contains all the graphical data of

a given binary system either as published in the Bulletin of Alloy Phase

Diagrams or in the ASM compendium "Binary Alloy Phase Diagrams". The critical

points of the diagram, the invariant reactions, the crystal data of all solid

phases of a system are filed in the database. All the graphical and numerical

data can be assessed by an easy search program.

Throughout the year, the database was loaded continually. It now contains the

data of approximately 1600 binary phase diagrams (9000 phases, 7300 invariant

reactions). The database is essentially complete and is ready to be

transferred to ASM INTERNATIONAL. It is planned initially to offer the

database off-line. Later the numerical data part of the database may be made

available in a form suitable for search by IBM personal computers. An

additional sub-database for the entry of ternary phase diagram data was added

to the Phase Diagram Database. The ternary database contains three relations:

Ternary - analogous to the binary relations of the binary database, Phases - data on phases in the ternary phase diagram, Invars - data on ternary invariant

(four phase) reactions. An additional relation, Quasi-Binary, may need to be

40
added to handle these unique ternary phase relations. To date, the data for

two ternary systems have been entered in this database.

Efforts have been made to improve and update computer programs for

thermodynamic calculation of phase diagrams. In line with this, the THERMOCALC

Database program was brought on board and utilized in evaluation of ternary

systems. A minimal theoretical model for phase relations between B2 , L2 X

, and

liquid phases for application in the NiAl-NiTi pseudo binary systems was formulated. This model permits evaluation of the roles of higher-order phase

transitions and T0 curves in rapid solidification processing of these alloys.

For the program BINARY (calculation and optimization program for binary phase

diagrams), an IBM-PC version was developed. A quick graphic display module

also was developed and added to BINARY.

The evaluation of Al-Cu-X ternary phase diagrams was initiated. The Al-Cu-Pb

and Al-Cu-Bi systems are completed. In these two Al-Cu-X ternaries, the phases

of the Al-Cu binary penetrate only slightly into the ternary diagram and the

published model for the Al-Cu system is adequate. However, for ternary

diagrams in which the phases of the Al-Cu binary penetrate deeply into the

ternary, the published Al-Cu model is oversimplified and is not suitable for

extrapolation of the binary Al-Cu phases into the ternary. For such systems, new modelling of the Al-Cu binary is being developed.

Experimental Studies of Alloy Stability

A. J. McAlister

The major theme of the past years effort on phase stability was the study of

the crystallization of metastable amorphous and icosahedral phase fractions in

Al-based alloys. Amorphous alloys of Mn in Al have been produced at NBS by

electrochemical deposition, in the composition range 16 to 40 wt% Mn. Heats

and extreme temperatures of transformation have been obtained and correlated

with structural data. Recovery to equilibrium appears straightforward, without

the complex series of intermediate transformations seen in our earlier studies

of splat quenched Al-Mn alloys. No glass temperature was observed, but in all

samples the initial crystallization peak is preceded by an extremely weak

exothermal peak not associated with any detectable structural change. Work

continues on the clarification of this question. Similar studies have been

carried out on splat quenched AlFeSi alloys which contain an amorphous fraction

in the as -quenched condition, and on splat quenched AlMnSi alloys containing a considerable icosahedral fraction. Some studies on sputtered amorphous MoW

alloys were also performed.

Electron Microscopy

A. J. Shapiro

The election microscopy analytical capabilities have been expanded with the

addition of a wavelength dispersive spectrometer to the recently acquired

JSM-840 Scanning Electron Microscope. The wavelength dispersive spectrometer

coupled with the Tracor 5500 and 5600 x-ray and image analysis has extended the

capabilities of the JSM-840 Scanning Electron Microscope to that of a full

fledged electron probe analyzer with light element analytical capability down

to boron.

41

ELECTRODEPOSITION David S. Lashmore

The Electrodeposition Group is responsible for measurements and standards

associated with electrodeposited metals and alloys. The objectives of the

group ares (1) the determination of the critical mechanistic , materials, and

process variables controlling the structure/property relationships of

electrodeposited coatings and the development of approaches that will result

in entirely new materials; (2) the provision of standards such as coatings

thickness standards, dye penetrant crack standards, and corrosion step test

standards; (3) the development of new standards requiring electrodeposition

for their fabrication or utilizing the unique properties of electrodeposited

alloys; and (4) the provision of government expertise to industry, through

research associates and standards organizations, and to government agencies,

through appropriate contracts and consulting arrangements. Following are some of the many areas in which coatings are important to the commerce of the

United States: (1) Strategic Materials - It has been shown that coatings can provide a 30% savings of imported raw chromium. Research on new alloys in

progress indicated that for many applications, coatings can replace bulk

stainless steels. (2) Corrosion-electroplated coatings play an important

role in corrosion protection. It has been estimated that the cost of

corrosion to the U.S. economy is in excess of 100 billion dollars per year.

(3) Wear - The cost of wear to the U.S. economy has been estimated to be

about 50 billion dollars per year. Electrodeposited coatings play an important role in improving wear properties and surface coatings can be

optimized for particular wear situations. (4) Electrodeposition Industry - specifically plays an essential role in the United States Economy. For

example, almost 900K tons of electrogalvanized sheet and strip are produced

annually with an estimated impact of about $150M per year projected by 1990,

approximately 550K tons of metal coated wire and wire produced per year, tin

plate accounts for 8800 tons with a dollar impact of $120M, and foil

production accounts for about $200M per year. (5) Magnetic Materials - All

hard disk drives are produced utilizing electrodeposition technology which

thus has an important impact on the United States computer industry. (6)

Processes - including decorative coatings, electroforming (compact discs)

and electronic applications (contacts, PC boards etc) are so important

that without electrodeposited coatings much of our current industry would

not be able to function in its present form.

FY 87 Significant Accomplishments

o Process Modelling - A mathematical model of a high speed alloy deposition

process on a moving substrate has been completed and is capable of

predicting the average and radial composition distribution. Though

the model was aimed at metal matrix composites, it has a broad impact on all continuous processes.

o Adhesion testing - Procedures have been developed and a number of

coating-fiber combinations have been measured for the first time for both

ceramic and metal matrix composites.

43
o Artificial Superlattices - Magnetic measurements of artificial

Cu-Ni supperlattices of all principle orientations have been made for

the first time and magnetic after effects have been observed in continuous

films

.

o Wear Resistant Coatings - It has been demonstrated that introducing a one dimensional structural modulation into chromium can yield an alloy with a significantly enhanced wear performance under abrasive condition.

o Aluminum Alloy Deposition - Alloys of aluminum manganese have

been produced. The electrochemistry of the chloroaluminate solutions has

been characterized and preliminary data on both microstructure and

mechanical properties have been obtained.

Metal Matrix Composites

C. R. Beauchamp, S. A. Claggett, C. E. Johnson, D. R. Kelley, D. S. Lashmore

,

J. L. Mullen, P. N. Sharpless, and G. R. Stafford

Metal matrix composites are known to have a number of properties

not attainable in homogeneous alloys. Such composites offer greater

stiffness, superior high temperature performance and reduced weight.

Unfortunately, a number of problems associated with current technologies

and microstructure increases their cost and limit performance. Problems

in the processing technology include the high cost of fabrication

and difficulty in controlling the nature of the fiber-matrix interfaces.

These interfaces, or interphase zones, not only are critical to bonding with

the matrix, but also control stress distribution within the composite itself.

The stress in the composite influences the fatigue behavior and crack

formation near the fiber-matrix interface. Work underway in the

electrodeposition group is addressing these problems by investigating how

multilayered coatings rapidly applied on continuous fiber can not only act as precursors for MMC's but serve to reduce cost and suppress unwanted

interfacial reactions.

The coated fiber is designed so that there is sufficient coating on the fiber

to constitute the matrix when the coated fibers are hot pressed into a structure. In addition, tailored or graded alloys adjacent to the fiber are selected to promote bonding and to avoid high temperature reactions which

might by deleterious to the composite performance. An idealized

microstructure is shown in figure 1. Finally, a eutectic coating is placed

on the "precursor" to reduce hot pressing temperature.

Tailored or Graded Alloys - There are three main types of tailored

structures which are being produced: (1) structure modulated alloys,

discussed below in the section on wear resistant coatings for the printing

industry, (2) composition modulated alloys or superlattices, readily

created by modulating composition. The modulation periodicity can be

nearly atomically controlled so that graded materials can be created

simply by varying the period of modulation. An example of a graded

structure produced in this way is shown in figure 2a, and the measured

hardness in figure 2b, (3) continuous concentration gradients, produced at

very high rates of speed on moving fibers. These materials are inherently in

a non-equilibrium state, with diffusion processes tending either to

44
homogenize the alloy or to lead to segregation into discrete phases

with sharp, step-wise concentration discontinuities at the phase

boundaries. In many systems, however, the non- equilibrium state can

be retained indefinitely when the diffusion processes are too slow

to have a significant effect on the composition distribution

within the material. The deposition techniques and the properties of

graded alloys produced by several of the techniques described above

are currently under investigation.

Deposition of the Aluminum Alloys - the Matrix - Aluminum alloys cannot be

efficiently deposited from aqueous solutions. However, their importance as matrix materials has led to an investigation of the properties of

aluminum alloys electrodeposited from eutectic or fused salt solutions. A

number of different alloys of aluminum with lithium, titanium, manganese,

vanadium and numerous other constituents can be produced at deposition

efficiencies exceeding 90%. These eutectic salt electrolytes operate at

low temperatures (about 150 centigrade) and thus provide a means for

measuring properties of composites created at the temperatures needed to

suppress carbide formation, a problem which limits the high temperature

use of these materials. In addition, the electrolytes are for the most

part non- toxic, so that there does not seem to be a significant obstacle

to eventual industrial adoption of the technology. Considerable progress

has been made in understanding the electrochemistry of the alloy

deposition process of aluminum-manganese. Deposits of pure aluminum have

a nodular texture and are quite often dendritic due to the very fast

kinetics associated with the reduction of Al2 Cl 7. The addition of MnCl2 to the melt dramatically increases the activation overpotential, thereby

promoting nucleation which results in specular deposits. The results of some linear sweep voltammetry showing the conversion of primary to

secondary current distribution with the addition of MnCl2 is shown in figure

3. The manganese content of the electrodeposit varies from 5 to 30 wt% and

is dependent upon deposition potential and the relative concentrations of

Al2 Cl7

- and Mn+ + in the melt. The potential dependence of alloy

composition allows one to create homogeneous, graded and modulated

structures from a single electrolyte; an example of a modulated alloy is

shown in figure 4. The structure of the as-deposited alloy appears to be

that of a metallic glass above 27 wt% manganese and a mixture of glass and

supersaturated aluminum below 27 wt% (figure 5). Upon heating to 400° C, the

glassy structure converts to the orthorhombic Al 6 Mn intermetallic while

the supersaturated phase converts to Al 6 Mn and aluminum. Both of these

transformations may occur through the formation of some interesting

metastable phases.

The hardness of the electrodeposit increases significantly with

heat- treatment (figure 6) suggesting that a dispersion/precipitation

hardening mechanism is operative. The ability to precisely control the

deposition process will allow the electrodeposition of alloys in the form of

coatings and matrix material (when deposited onto conducting reinforcement

for metal matrix composites) with improved mechanical properties.

Process Modelling - Much effort is being applied to model theoretically the

high speed deposition of alloys onto continuously moving fibers or wires and

to verify this modelling by actual high speed deposition on a small scale.

The mathematical model is now reasonably complete. The purpose of modelling

45
is of course to enable the prediction of composition or composition gradients

within the coating, and their dependence on the deposition parameters . A

model high speed plating cell has been constructed to complement the

mathematical model and will be tested initially with nickel alloy deposition'

onto tungsten wires and eventually with silicon carbide fibers with the more

complex series of coatings described above. A schematic diagram of the cell

design is shown in figure 7 and results of the model are shown in figure 8.

Adhesion Measurements - Fiber matrix adhesion is a very important

parameter in metal matrix composites. Techniques have been developed to

directly .measure this parameter by utilizing a modification of a instrumented microhardness testing instrument incorporating a load cell

and a displacement sensor. The technique is simply to cut a section of

the coated fiber perpendicular to its axis about 25Qum thick and polish

both sides with a diamond abrasive. The microhardness diamond, usually a Vickers indentor, is then aimed at the fiber and the load displacement

curve recorded on a computer system. An example of the raw data is shown

in figure 9 with adhesion values determined from a combination of the

surface area and the load at which slipping between the fiber and the

matrix is first observed. Some adhesion data for a number of different

fiber coating combinations is shown in figure 10.

Standard Reference Materials

H. J. Brown, H. G. Brown, F. Ogburn, D. R. Kelley, D. S. Lashmore, and

P. N. Sharpless

This year research on the production of tin/ lead standards continued. The

fluoroborate plating was selected as the best process and a number of

steel panels were plated. These panels were measured on both energy

and wavelength dispersive X-ray units. The coating thickness distribution

was determined on the energy dispersive unit. The computer programs for

converting XRF measurements to composition and mass per unit area were

tested with data obtained with the wavelength dispersive unit. The

resulting data enables the estimate of precision of the measurements. It was found that the minimum thickness of copper over the steel substrate

should be about AO micrometers in order for the copper to appear infinitely

thick. Surface roughness and its effect on the thickness measurements was investigated. Below a grit size of 600 the apparent thickness was not

affected.

It was found that the X-ray measurement changes as a function of time,

indicating that one of the species preferentially diffuses to the surface.

Little information relating to electrodeposited coatings was found in a review of the literature. Samples were prepared and measured periodically

for periods up to 80 days, and such measurements are being continued.

These changes are shown in figure 11. The total changes observed are of the

order of 2 to 3 %.

Approximately 6000 coating thickness standards were produced this last

year. This accomplishment represents about a 16% increase from last year

with no additional commitment of personnel. The increase in productivity

can be attributed to incorporation of a pneumatic shear, a new electronic

balance and improvements in the software used in the calibration. Most of

the SRM plating for FY88 is complete. Part of the effort in this group

46
the SRM plating for FY88 is complete. Part of the effort in this group

is aimed at serving industry through the recertification of coating

thickness standards. Thirty- seven coating thickness standards were recertified this last year for 8 corporations.

Wear Resistant Coatings for the Printing Industry

D. R. Kelley, C. E. Johnson, D. S. Lashmore, J. L. Mullen

A two year study of the electrodeposition on engraved currency printing

plates for the Bureau of Engraving and Printing (BEP) , in collaboration

with the Corrosion and Wear Group, was completed. Initially, the program

focused on developing an understanding of the process and process variables

along with measurement of properties of the electroformed printing plates.

Subsequent investigations focused on the characterization of abrasive wear

of various chromium electrodeposits and those metallic coatings by

laboratory accelerated wear tests and in situ wear tests of BEP. The

coatings were obtained by direct current (DC) plating, galvanostatic pulse

plating, and by varying operating parameters, such as temperature and

current density. Of the myriad of metal, metal alloy, and composite

coatings that were investigated for wear performance, seven types of

coatings exhibited an increase in wear performance over the current hard

chromium technology. The results of wear tests on these coatings, as determined by the laboratory accelerated wear tester, are summarized in

figure 12.

A composite coating of nickel-phosphorus-silicon carbide exhibited the

lowest rate of wear. This particular coating may have a surface too rough

for use on printing plates due to the carrying of ink but warrants

further investigation. The majority of the coatings investigated were chromium or chromium based coatings of which six types exhibited an increase in wear performance. The most significant of these was a newly

developed pulse plated duplex chromium coating which exhibited a factor of

two increase in wear over hard, microcracked chromium. The results of in

situ wear testing of chromium plated wiper blades at BEP were two fold.

Not only did the in situ wear testing provide a check of the laboratory

accelerated tester, but also demonstrated that chromium plating of the

wiper blade extended the life of the blade 10 to 15 times the life of the

unplated blade. This extended blade life resulted in a dollar savings of

$200,000 per year for BEP.

Electrodeposited Artificial Superlattices

D. S. Lashmore, S. A. Claggett, and R. R. Oberle

Research on electrodeposited artificial superlattices or microlayered alloys

has continued this past year with the successful development of electrolytes

to produce iron- tin modulated structures. These particular alloys provide

the opportunity to examine the vicinity of the interface between each

layer using both iron and tin Mossbauer spectroscopy. An optical

micrograph of a polished cross section of an iron-tin modulated structure

is shown in figure 13.

Magnetic measurements have continued on copper nickel and for the first

time a magnetic after effect has been observed in continuous alloys. These

measurements are discussed in the magnetic materials section of this report.

47
This finding is significant as nickel is supposed to relax very rapidly and

only nickel is magnetic in this particular alloy. That rapid relaxation

clearly does not take place is an indication that there is some interaction

between the domain structure across the copper barrier layers. Experiments - are now underway to examine magnetic properties of alloys with differing

copper-nickel ratio and to investigate any limitations on layer thickness.

48
METAL MATRIX COMPOSITES

Surface Coating to reduce

hot pressing temperature Tailored Interphase

for bonding and

distributing stress

Matrix Alloys

Ai-Mn Cu

Al-Ti

Al-V

Nl-W

N!~M©

SiC fiber

W»wi re Graphite tows

Fig. 1. Idealized Microstructure for a MMC precursor.

Fig.2a, Optical micrograph of an alloy made up of alternating

Ni and Cu layers with a periodicity that varies with thickness.

49
Graded Alloy Hardness

Fig, 2b. The microhardness KHN-lOg of the

structure shown in Fig. 2a.

Fig. 3. Linear sweep voltammetry for various MnCl concentrations.

50
Fig. 4. EDX linescan and polished cross-section of modulated deposit

Degrees Two Theta

Fig. 5. X-ray diffraction for various electrodeposited

aluminum-manganese alloys.

51
heat treated 400 °C

Initial Mn Wt% in Alloy

Fig. 6. KHN Hardness data, 10gs vs. alloy composition before

and after heat treatment

Fig. 7. A schematic diagram of a high speed bench-top cell showing

the bipolar electrode and three deposition chambers.

52
Metal

\

X

Metal

103

I • till lilt I I

9‘l

9H

9

:

'

9

ji

95

-0.250 V

I

C

1

i

‘ ""i “>—

r

1 .OE-6 2. OE-6 3.0E-6 4.0E-6 5.0E-6 6.0E-6

Radius (cm)

0.0E0 2.0E-5 4.0E-5 6.0E-5 8.0E-5 1.0E-4

Radius (cm)

0.0E0 5. OE-6 1.0E-5 1.5E-5 2.0E-5 2.5E-5

Radius (cm)

Fig. 8. Radial composition of the alloy for three different applied potentials.

Ultimate Shear Stress = 35.9 MPa

Time (msec.)

Fig. 9. Load-time curve for a typical adhesion

test

53
Fig, 10. Examples of adhesion data for a number of coating

fiber combinations.

>*

Inc

0

_c

_c0

05c

m

xzo

c

0

ow

0

CL

-Q70% Sn-8.3um

61% Sn-15um

71%Sn-6um

66% Sn-1 1 um

Fig. 11. Example of the variation in x-ray signal as a function of time for electrodeposited solder

(Pb-Sn) alloy.

54
**DC BEP Cr”

DC CrV alloy

DC Duplex Cr

PP Br. Cr

DC Trans. Cr

DC Cr+AI203

PP Duplex Cr

Ni-P+SiC

0 10 20 30

Wear Rate in g/ cycle (times E-08)

Fig. 12 . Summary of low wear rate deposits compared to the presently

used DC deposited chromium as determined by an abrasive slurry

wear testing instrument

Fig. 13. An Optical micrograph of an Fe-Sn modulated alloy.

55

NONDESTRUCTIVE CHARACTERIZATION Haydn N. G. Wadley

The Nondestructive Characterization Group's mission is to advance the

measurement science of nondestructive characterization and apply it to the

needs of materials science and engineering. Sensors are developed to better

control materials processing and understand the fundamentals of

transformation and damage mechanisms. The objective of this work is to find

ways to better control the artificial structures produced during materials

processing. One way this can be achieved is with a future generation of sensors able to directly measure the process conditions and microstructure

features of importance. This will permit computerized controllers (some of

which will feature artificial intelligence expert systems) to adjust the

process to produce a constant product in the most cost-beneficial manner even with varying raw materials.

A collaborative project with the Extruded Products Committee of the Aluminum

Association has resulted in a prototype eddy current sensor that was able to

measure "body" temperature during trials at Cressona's extrusion mill at

Cressona, PA. Work is continuing with the Association to identify a prospective vendor, and explore ways of deconvolving temperature gradients

from the sensor data. A modified version of the sensor has been used to

measure in situ dimensional changes during hot isostatic pressing (HIPing) of

aluminum and copper up to 550°C and 50 MPa. This DARPA funded program has

opened the way for new control schemes for HIPing and close interaction is

continuing with the Metallurgy Division's processing group to explore

development of an artificial intelligent (AI) controller for this process.

Research with the ultrasonic temperature sensor are continuing. Efforts to

extend successes with solid body internal temperature profiling to

solidifying bodies required that the problems of "breakout" and failure to

achieve acoustic paths due to poor wetting in the prototype experimental

system be solved. A new method for simulating continuous caster

solidification has recently been designed and constructed, and data from

liquid/solid bodies is now being analyzed. The ultrasonic porosity sensor completed in FY 1986 for the steel industry has this year been the recipient

of an IR-100 award.

Sensor research has been complemented by other programs directed at applying

nondestructive characterization methods to the study of phase transformation

and damage mechanisms. Research on ultrasonic methods to probe interfaces in

composites has proceeded rapidly with the theoretical prediction and

experimental verification of localized modes in several fibrous metal matrix

composites (Al-SiC, Al-B^C Al-B, Al-Graphite) . Present research is

investigating the role of an interphase (such as aluminum carbide between a SiC fiber and an aluminum matrix) on wave propagation and developing methods

to image interfaces (this in collaboration with Professor B. T. Khuri-Yakub

of Stanford University). Other ultrasonic studies are being used to

investigate internal friction phenomena in high temperature superconductors

near their Tc , and to attempt detection of "threading" dislocations emanating

from Si-GaAs interfaces - this latter in collaboration with Martin Marietta

Laboratories.

57
Acoustic emission techniques have been coupled with high resolution

mechanical property tests to measure interfacial cohesion in aluminum-SiC

fiber composites. By using special samples containing only a single oriented

fiber, many of the complexities of this measurement challenge have been overcome. Work is now progressing to explore the role of processing time and

temperature upon the interface strength and the effect of this upon damage

mechanisms in metal matrix composites. The feasibility of imaging with the

Mossbauer effect has been established. This will provide a potentially new way to noninvasively probe the microstructure of materials.

During FY 1987 collaborations and interactions with industry and academia

have continued to increase. Cooperative research programs with the American

Iron and Steel Institute, the Aluminum Association, Johns Hopkins University

and MIT (advanced composites) has continued. Ygal Gefen has spent a very

fruitful year with us while on sabbatical from Israel. New collaborations

with Professor B. T. Khuri-Yakub of Stanford to explore acoustic imaging of

MMC interfaces, and the Martin Marietta Laboratory at Baltimore to explore

the feasibility of in situ detection of interfacial dislocations during

molecular beam epitaxial growth of III-V compound semiconductor thin films on

Si substrates. Interactions with other Government agencies, notably ONE and

DARPA have been extended both to conduct research and provide program

development advice. A joint ASM-AIME symposium on "Intelligent Processing of

Materials and Advanced Sensors" held at the AIME-TMS Fall Meeting in Orlando

was organized.

FY 87 Significant Accomplishments

o A collaborative NBS/Aluminum Association program has resulted in the

successful testing of a prototype eddy current sensor for determining body

temperature of aluminum during extrusion.

o An eddy current sensor has been developed to sense density (in situ)

during hot isostatic pressing of aluminum, copper, and high Tc superconductors

.

o A single crystal aluminum-SiC fiber sample preparation and mechanical

testing approach has been perfected to allow fundamental studies of

interfacial effects on fracture of metal matrix composites. This approach

has allowed determination of the role of processing variables on the

cohesion and load transfer properties of Al-SiC composites.

o Ultrasonic waves have been theoretically predicted and experimentally

confirmed to be supported at the cylindrical interfaces of aluminum-SiC

fibrous composites. By exploiting the "leaky" character of these waves,

it has been found possible to measure local differences in ultrasonic

velocity thus creating the potential for interphase imaging.

o The concept of Mossbauer imaging has been recognized for the first time.

An imaging formulation has been developed and implemented successfully in one dimension.

58
Eddy Current Sensing - Temperature Measurement of Aluminum During Extrusion

Processing

A. H. Kahn, M. L. Mester*, and H. N. G. Wadley

* Research Associate, The Aluminum Association

Design and construction of a prototype model of an eddy current sensor for

measuring, every few seconds, the diameter, electrical conductivity, and the

temperature of aluminum rod during extrusion processing has been completed.

A plant demonstration and test were conducted in July 1987. This project has

been conducted as a joint effort of the Metallurgy Division, the NBS Office

of Nondestructive Evaluation program and The Aluminum Association (a

consortium of manufacturing and processing companies). The impetus for its

undertaking has been the objective of improved product quality and reduction

of rejected output through in-process temperature measurement and control.

The envisioned control system will use sensor acquired temperature

measurements in a feedback loop, performing off-line control of the initial

temperature of the aluminum billets and on-line control of the speed of

extrusion (itself a heat-generating process). The function of the

temperature measurement in the control loop is shown in figure 1

The prototype model is based on the use of a commercially available

Impedance/Gain- Phase Analyzer, with measurement initiation and recording of

data performed by a personal computer. Later, an application specific design,

requiring less versatility than needed for the development phase, could lead

to a smaller device capable of even more rapid measurement. A block diagram

of the prototype circuit is shown in figure 2. It is seen from the figure

that the measurement of the properties of the test sample is obtained from

the transfer impedance between the primary and secondary circuits. An audio

power amplifier is placed in the primary circuit to enhance sensitivity,

particularly at the lower frequencies. From the impedance measurements are obtained the diameter and conductivity of the aluminum rod. Since the

electrical conductivity of the test material is a continuously decreasing

function of temperature which may be measured for the alloy under study, the

impedance measurement provides the data required to deduce temperature , In

laboratory tests the instrument measured the temperature of heated aluminum

rods to within +/- 5°C, at the rate of one measurement per 1.25 sec.

The plant tests took place at the Cressona Aluminum Co., Cressona, PA. The sensor was placed within one foot of the die in the extrusion press.

Temperatures were measured during operation on round and square solid stock,

and also on hollow square tubing. Figure 3 shows a plot of measured

temperatures of 3/4 inch square solid stock as a function of time as the

speed of extrusion was intentionally varied. Factors influencing the

temperature are the temperature of the part of the billet being pressed

through the die and friction in the die, which generates heat. These effects

are seen in the figure. Cooling at the end of the process begins when the

extrusion was cut and the product transported away from the press.

59
Eddy Current Sensing - Measurement of Density During Hot Isostatic Pressing

A. H. Kahn, Y. Gefen**, M. L. Mester*, R. B. Clough and

H. N. G. Wadley

* Research Associate, The Aluminum Association

** Guest Scientist

In a DARPA cofunded project similar instrumentation to that used for the

aluminum extrusion sensor has been applied to the measurement of density of

metallic powders during sintering in a pressure furnace. The powder being

consolidated is sealed in an evacuated metallic tube and the tube is placed

in the furnace in the center of the concentric sensor coils. From impedance

measurements at high frequencies it is possible to infer the cross-sectional

area of the material being tested. As the powder is consolidated the tube

diameter decreases and a reading of diameter during the process can be

obtained. An example for a run on copper powder sealed in copper tubing is

shown in figure 4. This monitoring of the process enables one to test

theoretical models for sintering. The method shows promise for the design of

intelligent feedback control of temperature and pressure to optimize special

properties of the material being sintered.

Steel Sensors

M. Linzer, F. A. Mauer, D. Pitchure, S. J. Norton, J. R. Cook*, R. L. Heinrich**, and H. N. G. Wadley

* Research Associate, American Iron and Steel Institute

** Contractor at NBS

In 1982, a workshop sponsored jointly by NBS and the American Iron and Steel

Institute (AISI) identified a need for four types of sensors for use during

automated process control in the steel industry. Scientists from NBS and

AISI have collaborated in the development of two of these, one for automatic

detection of pipe and gross porosity in hot steel billets, blooms, or slabs

and the other for measurement of the temperature distribution within a solid

or solidifying body of hot steel. Both are based on ultrasonic measurement

techniques

Success in developing the pipe and porosity sensor depended on finding a way

to couple a sensitive piezoelectric transducer to a moving strip of hot steel

so that intense ultrasonic pulses could be transmitted into the steel and

echoes from internal discontinuities received. At the same time, thermal

insulation had to be incorporated between the hot steel and the transducer.

A buffer in the form of a rolling wheel was developed by Magnaflux

Corporation of Chicago to meet these requirements. In the past, such wheel

buffers have required pressures of as much as 140 MPa to achieve ultrasonic

coupling. A key NBS contribution has been the development of a high

temperature couplant to enhance the transmission of ultrasonic waves and

eliminate the need for heavy pressures that could result in damage to the

product

60
Tests at NBS and The Argonne National Laboratory in FY 1987 have confirmed

the sensor's ability to detect and measure internal porosity and flaws in hot

steel during processing, enabling steel producers to crop unsound material

early in the production cycle (the AISI has estimated the potential savings

at $1M per year for each installation using the sensor). The new sensor has

recently received recognition in the form of the IR-1Q0 award. NBS and

Argonne are jointly applying for a patent for the technique, and Magnaflux

Corporation is currently manufacturing sensors for the steel industry.

NBS has developed an internal temperature sensor in collaboration with

scientists from the AISI. The system, based upon time of flight measurement,

has been fully automated using two arrays of ultrasonic receivers, each

consisting of five piezoelectric transducers coupled to the test body through

buffer cones of AISI 304 stainless steel. These are to be replaced later

with non-contacting EMAT's (Electromagnetic Acoustic Transducers).

An improved method for determining small changes in the time of flight (TOF)

has been adopted which is particularly useful when the wave arrival is

obscured by high-frequency noise. The method is based on cross correlating

each high- temperature waveform with one recorded for a corresponding path at room temperature. The shift on the time axis that gives the maximum value of

the cross correlation coefficient gives the change in TOF between room temperature and the higher temperature.

Recent tests on a six- inch square block of AISI 304 stainless steel showed

excellent agreement between the ultrasonic temperatures and the temperatures

indicated by an embedded thermocouple at the center of the block (figure 5).

Linear regression analysis gave Ttc = 3.9 + 0.997 Tus as the expression

relating thermocouple readings, Ttc , and ultrasonic temperature readings,

Tus , indicating that calibration corrections do not exceed 5°C.

A ten- channel ultrasonic system is being used for measuring temperature

fields and locating the solid/liquid interface in solidifying bodies.

Difficulty was experienced in simulating a solid shell with a liquid core in

the laboratory. Attempts to pour molten aluminum into a preformed shell

resulted either in a breakout of the liquid or failure of the liquid to wet

the solid as required to form a continuous ultrasonic path. Solidification

times (and thus the quantity of data that could be collected) were also very

limited. The present approach permits the core to be heated in place with

electric heaters. This system provides better control so that a portion of

the solid at the interface can be melted to remove any oxide before allowing

the solidification front to advance or even be held stationary.

The amplitude of the ultrasonic signal obtained with aluminum is at least

five times as great as that obtained with steel and the rise time of the

received pulse is so short that a faster transient recorder is needed to

adequately represent the waveform. A transient recorder with a sampling

interval of 5 nanoseconds has been obtained to replace the 32 nanosecond

units presently in use. This instrument, combined with the cross- correlation algorithm, promises to further reduce the scatter in measured

values of TOF, permitting an improvement in the precision of temperature

profiles and the resolution of solid/liquid interface.

61
Interface Characterization in Metal-Matrix Composites

J. A. Simmons, E. Drescher-Krasicka** , M. Rosen**, T. Hsieh**’

B. Elkind**, R. B. Clough, R. P. Quincoses, F.. S. Biancaniello , and H. N„ G.

Wadley

** Guest Scientists, Johns Hopkins University

The mechanical performance of metal matrix composites is strongly dependent

on interfacial elastic and anelastic properties and strength. In order to

measure these properties in situ, advanced traditional non-destructive test

methods have been developed. To isolate the phenomena and avoid additional

complications arising from multiple reinforcement elements, such as complex

stress states, model metal matrix composites were fabricated as acoustic

he teroj unctions with planar and cylindrical geometries.

In the planar geometry, using Fe-Ti, experiments determined the substantial

effect of microstructure and stress on the velocity of interface waves. These experiments showed the feasibility of generating interface waves other

than pure Stoneley waves at planar acoustic heterojunctions by mode

conversion of Rayleigh waves on the more dense medium, Table 1.

Weakly leaky ultrasonic guided interface waves (G.I.W.'s) in the cylindrical

geometry have been found to provide a new tool for interface characterization

in fiber reinforced composites, and have led to a preliminary design for a new type of acoustic microscope. The leakage from these modes offers the

opportunity for measurement of the quantities of import: local elastic

properties, defects and adhesion directly at the interface.

As a leaky wave travels along an interface, it radiates acoustic energy out

of the interface. Measurements on Al/stainless steel (figure 6) and Al/SiC

cylindrical interfaces show good agreement with the theoretically predicted

arrivals of radial-axial leaky interface modes. The elliptical particle

trajectories in these figures show the relative amplitudes of horizontal and

vertical displacement components. The continuous thick lines show the energy

path followed by a wave packet emanating from the interface as found by

integrating the Poynting vectors. The results show good agreement between

the measured points and calculated (continuous lines) of maximum flow of

acoustic energy due to leakage.

The calculated displacement field of the leaky radial axial G.I.W. for the

Al/SiC interface superimposed on the geometry of the sample is shown in

figure 7. This mode was detected on Al/SiC model samples and the dispersion

relation obtained for different frequencies used in the experiment agrees

with theoretical predictions [1]. Another weakly leaky mode at Al/SiC

interfaces was measured (points) and compared with the theoretical

predictions (continuous line), figure 8. The phase velocity of the mode

measured as a function of frequency agrees with the calculations and is

surprisingly high (18653 m/sec at 3 MHz and a fiber radius of 3.2 mm). This

mode was first detected, analyzed and separated from the other ultrasonic

arrivals by use of an acoustic microscope at Stanford University.

62
From these results, a new instrument for studying the elastic properties near

the interface zone is presently under preliminary development, figure 9.

This Interface Wave Acoustic Microscope uses leakage from the interface for

interface imaging.

The fiber and interface strength of model composites was measured in

instrumented tensile tests that were simultaneously monitored by acoustic

emission. The model composites consisted of a single fiber of SiC grown into

a single crystal of aluminum.

Single crystal Al , monofilament (SCS-2 type) SiC composites were fabricated

using a Bridgman- type technique. There were four types of specimen: rapidly

and slowly grown, with and without a carbon-rich fiber surface preparation.

As the composite (with a single fiber) is extended, it exhibits load drops in

the stress-strain curve. Measurement techniques have now been developed to

allow determination of fiber strength from the magnitude of these load drops.

The interfacial shear strength r and fiber tensile strength a

& in fiber

composites subjected to longitudinal loading are related by the formula: r =

(% l c /2d, where d and l c are respectively the fiber diameter and segment

length after fiber breakup is complete (the "critical length"), measured by

post-test metallography. By measuring each term on the right hand side of

this equation, the interface strength can be determined. The results are shown in Table 2. Fiber surface modification by carbon enrichment was effective in maintaining fiber strength and interface adhesive energy.

Rapidly cooling the specimens from the melt also minimized fiber and

interface degradation. There is evidence in the case of slowly cooled

materials, where the interface strength is less than the matrix strength,

that interfacial failure of a shear type occurred, i.e., by frictional slip

or fracture.

Acoustic emission measurements provided results in agreement with those

deduced from tensile tests, figure 10. The rapidly cooled composites showed

direct correspondence between the number of fiber fractures (as measured by

post-test metallography) and the number of acoustic emission events. The

interface strength was not less than the matrix strength, so that interfacial

failure was by plastic flow in the matrix. In contrast, the more slowly

cooled composites exhibited a substantial number of events in excess of the

number of fiber fractures, which were also much more energetic than those

from plasticity. These are attributed to interfacial failure, and

metallographic examination of the interface region shows the development of

interfacial cracks.

Reference

[1] H. N. G. Wadley, J. A. Simmons, E. Drescher-Krasicka , M. Rosen, R. B. Clough, T. Hsieh, K. Hirschman, F. S. Biancaniello ; Composite

Materials Interface Characterization, NBS Internal Report # 87-3630

63
Dislocation Measurement in Thin-Film Semiconductors

W„ L. Johnson and H. N. G. Wadley

A collaborative project has been initiated with researchers at Martin

Marietta in Baltimore, MD, with the goal of developing a technique for

continuously monitoring dislocation concentrations in epitaxial films during

molecular beam epitaxy (MBE) growth at “"600° C. The technique is to be used

initially as a tool in the development of a variety of high-speed

semiconducting films, such as GaAs on Si, free of the degrading effects of

dislocations. It may also be used for in-process quality control once these

materials reach commercial production.

The internal friction of the film/substrate wafer is being monitored.

Although internal friction data specific to these materials are incomplete,

it appears, from existing data on semiconductors that the attenuation always

increases exponentially with negative inverse temperature and linearly with

dislocation concentration. The attenuation, therefore, provides a measure of

dislocation concentration once the appropriate constants have been determined

for a given material. In order to perform the measurement, the wafer will be

supported by three needle points and set into forced vibration with a contactless capacitive drive. The drive voltage will then be turned off and

the decaying oscillations monitored. A feasibility study and initial design

of the system have been completed.

Mossbauer Imaging

S. J. Norton and L. H. Bennett and L. J. Swartzendruber

A novel imaging technique based on the Mossbauer effect has been proposed [1]

and experimentally demonstrated [2]. Recoil-less gamma-ray resonance, or the

Mossbauer effect, is a well-established spectroscopic tool in materials

science. A conventional Mossbauer experiment measures only a bulk average

of the gamma-ray resonant absorption coefficient over an absorbing specimen.

Thus spatial inhomogeneities within an extended absorber are lost in the bulk

measurement process. Mossbauer imaging, however, permits the reconstruction

of the two-dimensional spatial distribution, or an image, of the Mossbauer

absorption coefficient. In a more complex version of an imaging experiment,

spectroscopic information as a function of position is recoverable. As a consequence, in the latter version, true Mossbauer spectroscopy can be

performed for the first time in an imaging mode.

The idea of Mossbauer was inspired by the success of nuclear-magneticresonance imaging, since NMR and the Mossbauer effect share some fundamental

characteristics, both being nuclear resonance phenomena. NMR imaging has

recently found notable success in diagnostic medicine. While there are no foreseeable applications of Mossbauer imaging to medicine, applications in

materials science are thought to exist. The ability to perform Mossbauer

spectroscopy as a function of position within a sample, rather than in bulk,

should prove to be of value in the analysis of heterogeneous or composite

materials. Some potential high- resolution applications include the imaging

of grain boundary segregation, internal stress distributions, and magnetism

in ferromagnetic materials.

64
References

:

[1] Mossbauer Imaging, S.J. Norton, Nature (in press).

[2] Mossbauer Imaging: Experimental Result, U. Atzmony, S. J. Norton,

L. J. Swartzendruber , L. H. Bennett, Nature (in press).

Iterative Inverse Scattering

S. J. Norton

A general numerical approach to solving the exact, nonlinear inverse - scattering problem has been developed [1]. Most current inverse - scattering

algorithms or analytical inversion schemes are based on linear approximations

(e.g., the Born approximation) to the more exact, nonlinear inversescattering theory. These approximations fail to account for the distortion

of the internal wave field interacting with the scattering structures. Such

distortion, including multiple reflection and refraction effects, can often

be neglected in weakly scattering media (Born approximation) , but such

effects are frequently significant in strongly scattering media. Two wellknown iterative algorithms, steepest descent and conj ugate - gradient descent,

are used to solve the exact, nonlinear inverse-scattering problem from

scattering data by minimizing the mean- square error between the observed data

and data generated by the estimated scattering model. This approach offers

great flexibility, both in incorporating a priori information and in its

ability to weight the measurements in an optimal fashion based on error

statistics, which serves also to regularize an otherwise ill-conditioned

inversion. In minimizing the mean-squared error, many authors have proposed

Newton- like methods, but the above descent algorithms have superior global

convergence properties and avoid the need to invert a large matrix containing

second-derivative information. The problem can be formulated so that the

first iteration gives the Born inversion.

In all iterative approaches the gradient of the measurements with respect to

the model plays a fundamental role. An approximation to the gradient is

almost always derived by linearizing the measurement -model relationship (the

Lippmann- Schwinger equation), resulting in a gradient correct only to firstorder in the perturbation. Weston [J. Math. Phys . 20, 53-59, 1979] has

obtained an exact expression for the gradient, correct to all orders in the

perturbation, in the special case of monochromatic plane-wave illumination

and far-field detection. In the current work, Weston's results have been

generalized to the time domain and to point sources and receivers. In a one- dimensional numerical simulation of the nonlinear inverse-scattering problem,

the exact gradient has been shown to improve both the rate and stability of

convergence of the inversion algorithm to the correct solution. Work on extending the numerical simulations to two and three dimensions has begun.

Future work will include generalizing the current scalar-wave, inversescattering theory to elastic-wave scattering.

Reference

:

[1] Iterative Seismic Inversion, S. J. Norton, Geophys . J. R. Astr. Soc

.

(submitted)

.

65
ALUMINUM EXTRUSION TEMPERATURE SENSOR

Figure 1. Schematic illustration of the proposed use of the

eddy current temperature sensor in a feedback loop

controlling extrusion processing.

IMPEDANCE ANALYZER

GAIN/PHASE MODE OPERATION

Figure 2. Circuit diagram of the use of an impedance/gainphase analyzer to measure electrical resistivity by a noncontact method. The two coils are concentric solenoids; the

test sample is passed through the coil system.

66
3/4 X 3/4 SQUARE AT VARIED SPEEDS

Figure 3. Record of temperature measurements on 3/4 square

stock during extrusion processing. Extrusion speed was

intentionally varied for demonstration purposes.

TIME (HOURS)

Figure 4. Plots of pressure, temperature, and relative

density vs time for a HIP (hot isostatic pressing) run on

copper powder sealed in a copper tube. The relative density

was calculated from diameter measurements collected by the

eddy current sensor.

67
ULTRASONIC TEMPERATURE/°C

Figure 5. Comparison of temperature at center of steel block

measured by ultrasonic cross-correlation technique and

embedded thermocouple.

<•>

25JO

19.40 E

E 13.00

6.60

0-20

:

III!""

0?; m 1 i :

I U M M

mm

! Expari man* (

hHTT fi. i i {

L

1 { ! 1 !

oo R 2.5 MHz L

4 R 2.5 MHz S

T • 2.5 MHz - Interface Wave

-2J00

(c)

36.40 Z (mm)

62.00 1 2 3 Amplitude (mV)

/

Figure 6. Experimental identification of three leaky radialaxial displacement modes created in a 3.2 mm radius

cylindrical aluminum "tunnel" of 62 mm length. Experimental

intensity profiles of leakage at the top and end surfaces are

shown superimposed with calculations for each of the modes.

68
R IN MM R IN MM © f\> C O) OD

Figure 7. Predicted displacement fields for a leaky guided

interface wave previously detected experimentally in Al/SiC

at two selected frequencies. The radius of the SiC rod here

is 3.17 mm and that of the outer aluminum is 10 mm. Since

only the product R*F determines these curves, the same figure

would hold for a 3.2flm radius rod at gigahertz frequencies.

69

10

.00

-
VELOCITY

IN

HM/mS

MODE I Al-SiC

Figure 8. Calculated dispersion curve for a high phase

velocity leaky mode in Al/SiC as compared with experimental

measurements (shown as circles with error bars)

.

Frequency

Synthesizer

' i

Computer

i i

Figure 9. Schematic view of Interface Wave Acoustic Microscope.

70
SlueAg jo jequiriN aAijeiniuno

•H d) U tea

71

gure

10.

Cumulative

amplitude

of

AE

events

in

relation

to

ta.lographioally

observed

fiber

fractures

for

two

types

of

ocessing

(slow

and

rapid

cooling)
STEEL/TITANIUM

°

DUPLEX

PLATE

Interface

Wave

Velocity

Predicted

(m/s)

3247 3232 3170 CM

CO

3175 3166 3233 3218

(Measured

(

m/s

)

m

+1

r*- T"CMCO

3217

±

15 inm

H

(0CM

CO

3166

±15

3221

±

55

3162

±15

3223

±15

3206

±15

Predicted Wave Type

Stoneley Leaky In

Ti

Divergent

in

Steel

Stoneley

Divergent

in

Steel j

Stoneley Stoneley Leaky in

TI

Rolling

Direction

of

TS

Plate H = H = H — H =

Case No. < 0 <CM

CD

CM <CO

CD

CO

4A CD

4340

STEEL

PROPERTIES

Shear

*6 11*

s

N

*0

3170 3175 3235

Long

Velocity (m/s) 5952 5868 5869 5934

ZrT

<A E 0 i

7840 7805 7817 7839

Microstructure

Fine

Pearlite

(Held

at

1200F)

Tempered

Martensite

(Quenched

and

Temp.)

Bainite

(Air

cooled)

Fine

Pearlite

(As

ReceivedHot

Rolled)

CM «

(O £

II =

o» e n

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a o-o -2c

EiS

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w

o -

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<CO

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o 3 C/5

72

Table

I.

Interface

wave

velocities

for

four

different

microstructures

in

4340

steel

and

two

different

orientations

of

a

block

of

rolled

Ti-6A1-4V.
C/3 WD

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at at tj >H C 4"* hn C/3

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n

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at 00 00 ® © r—'l e<3 daM3wm®2

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73

MAGNETIC MATERIALS Lawrence H. Bennett

The Magnetic Materials Group is concerned with the measurement of the

magnetic properties of advanced magnetic and superconducting materials. The

objectives are (1) to relate the metallurgical, magnetic and electronic

structure to the magnetic and superconducting properties of materials, (2) to

develop new and improved magnetic measurement methods, (3) to develop

magnetic reference standards, (4) to apply magnetic phenomena to the

nondestructive evaluation of materials and structures, and (5) to provide

expertise to industry, universities and other government agencies.

Magnetic materials are important to the commerce of the United States. For

example, the sales of soft magnetic materials (primarily for information and

data storage) amounts to more than 25 billion dollars per year. The sales of

hard magnetic materials (primarily for motors) are more than one billion

dollars per year and have been recently increasing due to the discovery of

supermagnetic rare-earth alloys. Magnetic methods of nondestructive

evaluation are used for quality control practically everywhere steel is used.

FY 87 Significant Accomplishments

o A time -dependent magnetization was discovered in textured Ni-Cu

compositionally-modulated alloys. The mechanism for this unexpected

magnetic aftereffect, which has both scientific and technological

implications, is not yet fully understood.

o Meissner effect measurements were used to characterize the new high

temperature superconductors of the type Ba2 YCu3 07

_ x as a function of

processing changes. Transition temperature, transition width, magnetic

critical currents, and superconducting fraction were all measured.

o Thin- film high Tc superconducting oxides have been prepared directly from

the vapor with no subsequent thermal treatment required by a novel method

of laser ablation. The superconducting transition temperatures for the

ablated thin films of Lax 85 Sr0 15 Cu0^. x at 41. 5K and of Ba2 YCu3 07

_ y at

94.5 K are the same as for the bulk targets.

o Co-sputtering was used to produce a granular-metal thin film containing an immiscible mixture of nanometer- sized particles of a magnetic oxide

(Fe 3 04 ) and a nonmagnetic metal (Ag) for the first time. In addition to

superparamagnetic behavior, it was found that only a very small percentage

of Ag was required to obtain the granular-metal morphology.

o A temperature hysteresis in the initial magnetic susceptibility of rapidly

solidified Monel, suggesting metastable magnetic equilibrium, was discovered.

o The local topology of atoms in crystals, studied using a modified WignerSeitz construction, has been shown to be able to predict the correct

orientations of the magnetic anisotropies in hard magnetic materials.

o An ASTM round- robin test on standard flaws for magnetic particle NDE has

been initiated.

75
Magnetic Properties of Materials

L. J. Swartzendruber , R. D. Shull, U. Atzmony* and L. H. Bennett

*Guest Scientist - Nuclear Research Center - Negev, Israel

Granular metals - An investigation was initiated of this class of advanced

thin-film magnetic materials. In these cermet-like materials, a mutually

immiscible metal and dielectric are codeposited. Granular metals have been

found to possess a multitude of electronic and magnetic phenomena including

ferromagnetism, superparamagnetism, spin-glass behavior, percolation effects

And superconductivity. For example, a four-fold enhancement in the

superconducting critical temperature of Al was reported in the granular metal

Al + Al2 03

. Co - sputtering was used to produce a granular -metal thin film

containing an immiscible mixture of nanometer-sized particles of a magnetic

oxide (Fe 3 0A ) and a nonmagnetic metal (Ag) for the first time. In addition

to superparamagnetic behavior, it was found that only a very small percentage

of Ag was required to obtain the granular-metal morphology (see Figure 1).

CMA - Measurements have been made of the magnetic properties of Ni-Cu

compositionally-modulated alloys (CMA) fabricated with the use of pulsed

potentiostatic deposition by the Electrodeposition Group. Textured samples were produced by epitaxial deposition in each of the three principal cubic

orientations. Vibrating sample magnetometry was carried out at NBS

Ferromagnetic resonance and SQUID magnetometry was performed at the Naval

Research Laboratory in a cooperative research effort. A time -dependent

magnetization was discovered (see Figure 2) in these textured samples. The

mechanism for this unexpected magnetic aftereffect, which has both scientific

and technological implications, is not yet fully understood. It is possible

that the mechanism is not related to the modulation per se but is inherent in

each isolated nickel layer. This possibility will be tested by increasing

the Cu layer thickness in the CMA.

Temperature hysteresis - An unexpected temperature hysteresis was discovered

in the initial magnetic susceptibility of rapidly solidified Monel

(Ni 72 Cu 28 ). The hysteresis is exhibited by higher susceptibility values

during the cooling-down stage compared to the warming up. A transformation

between the two values can be abruptly induced by an external disturbance,

suggesting that the higher values represent metastable magnetic equilibrium.

Icosahedral phase - Combining magnetic susceptibility measurements and

nuclear magnetic resonance, a theory of enhanced magnetism in icosahedral AlMn was refuted. Instead, it is likely that the low temperature magnetism

often observed in these alloys is due to sample inhomogeneities. Using

nuclear magnetic resonance in crystalline Al 12 Mn, a theory of the icosahedral

phase by Linus Pauling was effectively refuted.

Local topology - Using a modified Wigner-Seitz (or Voronoi) construction, we continue to study the local topology of atoms in magnetic materials in

collaboration with Dr. R. E. Watson of Brookhaven National Laboratory. In

addition to the relation between the occurrence of strong magnetism and

"disclination" paths inferred from our computations, we have shown that the

correct orientations of the magnetic anisotropies in hard magnetic materials

can be derived.

76
High-Temperature Superconductors

L. J. Swartzendruber , R. D. Shull, U. Atzmony* and L. H, Bennett

Magnetic measurements of the new high temperature superconductors of the type

Ba2 YCu3 07

_ x were made to help determine the influence of varying process

parameters on the quality of the superconducting material. The samples were prepared and processed in the Ceramics Division. As an example, a hysteresis loop made in a vibrating sample magnetometer at 38 K is shown in

Figure 3. From such data, critical currents and critical fields are obtained. Using an automated ac susceptometer featuring a flow dewar to

determine the relative Meissner effect, the superconductors were characterized as a function of processing changes. Transition temperature,

transition width and superconducting fraction were all measured (for an example, see Figure 4). Measurements could be made from 6 to 400K.

Thin- film high Tc superconducting oxides have been prepared directly from the

vapor with no subsequent thermal treatment by a novel method of laser

ablation. This work was carried out in a cooperative research program with

Dr. Kishin Moorjani, of the Applied Physics Laboratory of Johns Hopkins

University. The superconducting transition temperatures for the ablated thin

films of Lax 85 Sr0 15 CuOA

_ x at 41 . 5K and of Ba2 YCu3 07

_ y at 94.5 K are the same as for the bulk targets.

Magnetic NDE

L. J. Swartzendruber

A variety of magnetic methods are currently being used in nondestructive

evaluation, both for detecting defects and for verifying material properties.

Some of these methods, such as magnetic particle inspection, magnetic flux

leakage testing, and magnetic permeability measurement, are widely used in

industry, the first two for defect detection, and the latter for property

determinations such as ferrite content in stainless steel welds. Magnetic

property measurements (e.g., saturation magnetization, coercivity,

Barkhausen noise, and initial permeability) contain a wealth of information

concerning material properties that has barely begun to be exploited.

One of the primary standard samples presently used in magnetic particle

inspection (perhaps the most used of all nondestructive evaluation methods)

has been the so-called Ketos ring. This is a circular ring made of a specific tool steel with specified dimensions and with twelve holes drilled

at various depths. Based on measurements performed at NBS and elsewhere, it

has recently been realized that a wide variation in properties, and hence in

test results, are exhibited by these rings. As a temporary solution, a new heat treatment has been selected for these rings which appears to reduce

their variability to an acceptable level. This new heat treatment is

currently being incorporated into various military and industrial standards.

To provide for a better standard, we have initiated and are currently

coordinating an ASTM round robin test on artificial flaw standards. The

round robin is designed to relate the results obtained on the flaw standards

to results on the test ring and on actual parts using developed procedures.

Based on the results of this round robin, and on further tests at NBS, we will appraise such flaw standards to be NBS Standard Reference Materials.

77
Magnetization,

Fig. 1. Granular metal (iron oxide +

Ag) . TEM picture shows conglomerated

iron- oxide and silver imbedded in a thin- film matrix of interconnected

nanometer- sized Ag (dark) and Fe 3 04 (light) granules.

Fig. 2. Magnetic aftereffect in a

[ 111 ] -textured Cu/Ni compositionallymodulated alloy. Magnetization vs. natural logarithm of the time after

reducing the applied field.

T = 38 K

Field, kOe

Fig. 3. Hysteresis loop for a sample

of Ba2 YCu3 07 _ x measured in the

vibrating sample magnetometer at 38 K

The data points are shown as squares.

The inset shows the virgin curve. From such data, critical currents and

critical fields are obtained and help

determine the influence of varying

process parameters on the quality of

the superconducting material.

0.2 - d

2 o - 3

0

C/l«

- 0.2 - o

N - 0.4 - e Real Susc.

IS T Im. Susc. o

-°- 6 ' Resistivity

4->03 o; - 0.8 -

-l - "

•1 '

1 ~ 11 1 1 r1 1i

50 70 90 110 130 150 Temperature, K

Fig. 4. Measured ac magnetic

susceptibility and electrical

resistivity for Ba2 YCu3 07 _ x

. The

temperature where = h the material is

superconducting (as determined from the

real part of the susceptibility) , the zero in resistivity, and the peak in the

imaginary part of the susceptibility,

all occur at approximately the same temperature

.

78

Resistivity,

m

ohm-cm
PUBLICATIONS

Metallurgical Processing Group

Bendersky, L. A.; Biancaniello, F. So; TEM observation of icosahedral, new crystalline and glassy phases in rapidly quenched Cd-Cu alloys.

Scripta Met. 21; 531; 1987.

Bendersky, L. A.; Biancaniello, F. S. ; Boettinger, W. J.;

Perepezko, J. H. ; Microstructural characterization of rapidly solidified

Nb-Si alloys. J. Mat. Sci. and Eng. 89; 151; 1987.

Bendersky, L. A.; Biancaniello, F. S.; Boettinger, W< J.;

Perepezko, J. H„; Microstructure of rapidly solidified Nb-Si alloys.

Mats. Sci. and Eng. 89; 151; 1987.

Bendersky, L. A.; Biancaniello, F. S.; Schaefer, R. J.; Phase separation

in AljQSi^yFej 3 alloy. J. Mat. Res.; in press.

Bendersky, L. A.; Graves, J. A.; Biancaniello, F. S.; Perepezko, J. H.;

Boettinger, W. J.; Pathways for microstructural development in TiAl.

Proceedings of Sixth International Conference on Rapidly Quenched Metals;

Montreal, Canada; J. Mat. Sci. and Eng.; 1987; in press.

Bendersky, L. A.; Kaufman, M. J. ; Boettinger, W. J.; Biancaniello, F. S.;

Solidification of an 'amorphous' phase in rapidly solidified Al-Fe-Si

alloys. Proceedings of Sixth International Conference on Rapidly

Quenched Metals; Montreal, Canada; J. Mat. Sci. and Eng.; 1987; in press.

Bendersky, L. A.; Ridder, S. D.; On the glass formation in system

forming icosahedral quasicrystals. Mat. Res. Soc. Symp. Proc.; Vol. 80;

349; 1987.

Bendersky, L. A.; Schaefer, R. J.; Formation of quasicrystals. Physical

140A; 298; 1986.

Blendell, J. E. ; Handwerker, C. A.; Shen, C.; Dang, N.-D.; Diffusioninduced grain boundary migration in ceramics. Interfaces in ceramics;

J. Pask, ed.; Materials Science Research; Plenum Press; 1987; in press.

Boettinger, W. J.; Microstructural variations in rapidly solidified

alloys. Proceedings of Sixth International Conference on Rapidly

Quenched Metals; Montreal, Canada; J. Mat. Sci. and Eng.; 1987; in press.

Boettinger, W. J.; Bendersky, L. A.; Biancaniello, F. S.; Cahn, J. W.;

Rapid solidification and ordering of B2 and L2| phases in the NiAl-NiTi

system. Proceedings of Sixth International Conference on Rapidly

Quenched Metals; Montreal, Canada; J. Mat. Sci. and Eng.; 1987; in press.

Boettinger, W. J.; Bendersky, L. A.; Coriell, S. R. ; Schaefer, R. J.;

Biancaniello, F. S.; Microsegregation in rapidly solidified Ag-15 wt% Cu

alloys. J. Cryst. Growth 80; 17; 1987.

79
Boettinger, W. J.; Bendersky, L. A.; Schaefer, R. J.;

Biancaniello , F. S.; On the formation of dispersoids during rapid

solidification of an Al-Fe alloy . Met. Trans. A; 1987; in press.

Boettinger, W. J.; Coriell, S. R. ; Microstructure formation in rapidly

solidified alloys. Proceedings of NATO Advanced Research Workshop on Rapid Solidification Technologies; P. R. Sahm, H. Jones, C. M. Adam,

eds.; NATO ASI Series E-N0114; Martinus -Nijhof ; Dodrecht; p, 81; 1986.

Boettinger, W. J.; Voorhees, P. W. ; Dobbyn, R. C.; Burdette, H. E.; A

study of the coarsening of liquid- solid mixtures using synchrotron

radiation microradiography. Met. Trans. 18A; 487; 1987.

Coriell, S. R. ; McFadden, G. B.; Voorhees, P. W. ; Stability of a planar

interface during solidification of a multicomponent system. J. Cryst.

Growth 82; 295; 1987.

Hackney, S. A.; Biancaniello, F. S.; Directional invariance of grain

boundary migration in the Pb-Sn cellular transformation and the Turnbull

hysteresis. Scripta Met. 20; 1417; 1986.

Hackney, S. A.; Biancaniello, F. S.; Experimental indications of a low

undercooling instability in the cellular mechanism of discontinuous

precipitation. Scripta Met. 21; 371; 1987.

Handwerker, C. A.; Diffusion induced grain boundary migration in thin

films; in Diffusion in Thin Films. Gupta, D.; Ho, P., eds. Noyes

Publications; 1987; in press.

Handwerker, C. A.; Morris, P. A.; Coble, R. L. ; Effects of chemical

inhomogeneities on grain growth and microstructure in Al2 03

. J. Amer.

Cer. Soc.; 1987; in press.

Handwerker, C. A.; Vaudin, M. D.; Blendell, J. E.; Equilibrium crystal

shapes and surface phase diagrams at surfaces in ceramics . Proceedings

of Conference on Interface Science and Engineering; Lake Placid, NY. J. de Physique Colloque; 1987; in press.

Johnson, W. C„; Voorhees, P. W. ; Elastic interaction and stability of

misfitting cuboidal inhomogeneities. J. Appl. Phys . 61; 1610; 1987.

Johnson, W. C.; Voorhees, P. W. ; Phase equilibrium in two phase coherent

solids. Met. Trans. 18A; 1213; 1987.

Kaysser, W. A.; Sprissler, M. ; Handwerker, C. A.; Blendell, J. E.; The

effect of a liquid phase on the morphology of grain growth in alumina.

J. Amer. Cer. Soc. 70[5]; 339; 1987.

Laria, V. J.; Johnson, W. C.; Voorhees, P. W. ; Growth of a misfitting

coherent precipitate. J. Mat. Res.; 1987; in press.

McAlister, A. J.; Bendersky, L. A.; Schaefer, R. J.; Biancaniello, F. S.;

Transformation of the icosahedral phase in rapidly quenched Al-rich Al-Mn

alloys. Scripta Met. 21; 103; 1987.

80
McFadden, G. B.; Coriell, S. R. ; Thermosolutal convection during

directional solidification. II. flow transitions. Phys . Fluids 30 (3);

659; 1987.

McFadden, G. B.; Voorhees , P. W„ ; Boisvert, R. F. ; Meiron, D. I.; A

boundary integral method for the simulation of two-dimensional particle

coarsening. J. Sci. Computing 1; 117; 1986.

Perepezko, J. H. ; Boettinger, W. J. Kinetics of resolidification.

Surface alloying by ion electron and laser beams; L. E. Rehm, S. T.

Picraux, K. H. Wiedersich, eds . ; ASM; Metals Park, OH; 51; 1987.

Ridder, S. D.; Biancaniello , F. S.; Process control during high pressure

atomization. Proceedings of Sixth International Conference on Rapidly

Quenched Metals; Montreal, Canada; J. Mat. Sci. and Eng.; 1987; in press.

Rottman, C.; Theory of phase transitions at internal interfaces.

Proceedings of Conference on Interface Science and Engineering; Lake

Placid, NY. J. de Physique Colloque; 1987; in press.

Rottman, C.; Thermal fluctuations in low-angle grain boundaries, Acta

Met.; 1986; in press.

Schaefer, R. J.; The metallurgy of quasicrystals. Scripta Met. 20;

1187; 1986.

Schaefer, R. J.; Biancaniello, F. S.; Cahn, J. W. ; Formation and

stability range of G phase in the Al-Mn System. Scripta Met. 20; 1439;

1986.

Schaefer, R. J.; Bendersky, L. ; Formation of quasicrystals in rapidly

solidified Al alloys. Mat. Res. Soc. Symp . Proc .

;

Vol. 58; 217; 1986.

Schaefer, R. J.; Bendersky, L. ; Biancaniello, F. S.; Nucleation and

growth of aperiodic crystals in aluminum alloys. Proceedings of

International Workshop on Aperiodic Crystals. Journal de Physique, Coll.

C3, Tome 47; 311; 1986.

Schaefer, R. J.; Bendersky, L. A.; Shechtman, D.; Boettinger, W. J.;

Biancaniello, F. S.; Icosahedral and decagonal phase formation in Al-Mn

alloys. Met. Trans. 17A; 2117; 1986.

Schaefer, R. J.; Bendersky, L. A.; Shechtman, D.; Boettinger, W. J.;

Biancaniello, F. S.; Metallurgy of phase relationships of icosahedral

Al-Mn. Met. Trans. 17A; 2117; 1986.

Schaefer, R. J.; Bendersky, L. A.; Shechtman, D.; Boettinger, W. J.;

Biancaniello, F. S.; Icosahedral and decagonal phase formation in Al-Mn

alloys. Met. Trans. A; 1986; in press.

Vaudin, M. D.; Handwerker, C. A.; Blendell, J. E.; Electron microscopy

studies of diffusion induced grain boundary migration in ceramics.

Proceedings of Conference on Interface Science and Engineering; Lake

Placid, NY. J. de Physique Colloque; 1987; in press.

81
Voorhees, P. W. ; McFadden, G. B.; Boisvert, R. F. ; Meiron, D, I.;

Numerical simulation of morphological development during late stage phase

separation in two dimensions. Acta Met.; 1987; in press.

Voorhees, P. W. ; Schaefer, R. J.; In situ observation of particle motion

and diffusional interactions during coarsening. Acta Met. 35; 327; 1987.

Corrosion and Wear Group

Anderson, D. B. ; The NACE-NBS Corrosion Data Program. Proc . 1987

Tri-Services Corrosion Conference.

Bertocci, U. ; Leigh, S.; Van Orden, A.C.; Yang, G.; Statistics of

pit initiation: analysis of current transients during passive film

breakdown. Mat. Res. Soc . Symp . Proc.; Vol. 84; 1987 Materials Research

Society.

Bertocci, U. ; Pugh, E. N. ; Modelling of the potential at the tip

of a transgranular stress-corrosion crack in the alpha-brass -ammonia

system. Conf. Proc. National Physical Lab, Teddington, Middlesex, UK;

Oct. 1-3, 1984; Corrosion Chemistry Within Pits, Crevices and Cracks;

p 187-201; Edited by A. Turnbull.

Bertocci, U. ; Statistics of localized breakdown noise. Proc. of NACE

International Conf. on Localized Corrosion 1987.

Bertocci, U. ; Pugh, E. N. ; Modelling of electrochemical processes during

transgranular stress corrosion cracking of copper-base alloys. Proc.

International Congress on Metallic Corrosion; in press.

Blau, P. J.; A model for run-in and other transitions in sliding

friction. ASME Journal of Tribology; Vol. 109 (1987); p 537-544.

Blau, P. J.; Whitenton, E. P.; Abrasive break-in modeling of steel,

aluminum, and PMMA. Submitted to WEAR 1987.

Blau, P. J.; Doyle, E. D.; Metallographic evidence for the nucleation of

subsurface microcracks during unlubricated sliding of metals. WEAR 1987;

Vol. 117; p 381-387.

Cassagne, T. B.; Kruger, J.; Pugh, E. N. ; The role of the oxide film in

the transgranular stress corrosion cracking of copper. ASTM Proc. on Environmentally-Assisted Cracking: Science and Engineering; in press.

Craig, B. ; Jones, R. H.; Kamdar , M. H.; Ricker, R. E.; Environmentally

induced cracking. Metals Handbook; Vol. 13; Corrosion; ASM International;

Metals Park, OH; 1987; in press.

Czichos, H, ; Ruff, A. W. ; Results of the Versailles Advanced Materials

and Standards (VAMAS) interlaboratory study on west test materials.

VAMAS Bulletin, 1987; in press.

82
Early, J. G. ; Smith, J. H.; Weldability of a leaded carbon steel.

NBSIR- 87 - 3598 ; June 1987.

Escalante, E., Whitenton, E.; Qiu, F. ; Measuring the rate of corrosion

of reinforcing steel in concrete. Federal Highway Administration; NBSIR

86-3456; October 1986.

Escalante, E. ; The effect of soil resistivity and soil temperature on

the corrosion of galvanically coupled metals. Galvanic Corrosion of

Metals; ASTM STP 978; July 1987.

Escalante, E.; Corrosion testing in soil. Metals Handbook, Ninth

Edition; Vol. 13; September 1987.

Escalante, E.; Concepts of underground corrosion. The Effects of Soil

Characteristics on Corrosion; ASTM STP; in press.

Fraker, Anna C.; Corrosion of metallic implants for prosthetic devices.

American Soc . for Metals Handbook; Corrosion; Vol. 13; 1987.

Freeman, R. W. ; Salkind, A. J.; Viswanathan, V.; Hall, D. E.;

Lipka, S. M. ; Impregnation and performance of fiber mat nickel

electrodes. Electrochemical Society Extended Abstracts; Vol 87-1; 1987.

Hall, D. E. ; Electrodeposited metal coatings on graphite fibers. Proc.

Symp . Electrodeposition Theory, Technology and Practice; D. R. Turner and

L. T. Romankiw, Editors; The Electrochemical Society; 1986.

Interrante, C.; Escalante, E. ; Fraker, A.; Kaufman, M. ; Liggett, W.

Shull, R. ; Evaluation and compilation of DOE waste package test data.

Biannual Report Covering the Period December 1985 to July 1986.

NUREG/CR-4735 ; Vol. 1; March 1987.

Interrante, C. ; Escalante, E. ; Fraker, A.; Harrison, S.; Ricker, R. E, ; Ruspi, J.; Shull, R. ; Evaluation and compilation of DOE waste package

test data. Biannual Report Covering the Period August 1986 to January

1987. NUREG/CR-4735; Vol. 2; September 1987.

Ives, L. K. ; Peterson, M. B.; Whitenton, E. P.; Mechanisms of galling

and abrasive wear. Proc. of the Fossil Energy Materials Conference; Oak

Ridge, TN; May 1987; in press.

Ives, L. K. ; Peterson, M. ; Ruff, A. W. ; Harris, J. S.; Boyer, P.A.;

Wear due to printing inks. NBSIR 87-3574; Report to US Bureau of

Printing and Engraving; 1987.

Lipka, S. M. ; Hall, D. E.; Porous nonsintered nickel coated graphite

fiber electrode structures. Electrochemical Society Extended Abstracts;

Vol. 87-1; 1987.

Peterson, M. B.; Ives, L. K. ; Bhansali, K. J.; A literature review of the

galling process. Metal Transfer and Galling in Metallic Systems;

AIME; New York, NY; 1987; in press.

83
Peterson, M. B.; Advances in tribomaterials 1937-1987-2002. Proc . of

International Conference on Lubrication-Lubrication 50 Years On;

I.Mech.E.; London, UK; 1987.

Polvani, R. S.; Ruff, A. W. ; Robbins, J. C.; Dynamic microindentation

of RDX: effect of rate on plasticity and fracture. NBS Report to Office

of Naval Research; 1987.

Polvani, R. S.; Ruff, A. W. ; Whitenton, E. P. ; A dynamic microindentation apparatus for materials characterization. Journal of Testing

and Evaluation; ASTM; in press.

Ricker, R. E.; Contributions to the book: Metals Handbook Ninth Edition;

Vol. 12; Fractography . Publ. ASM International; Metals Park, OH; 1987.

Ricker, R. E.; The influence of environment on the fatigue properties of

aluminum alloys. Modeling Environmental Effects on Crack Growth

Processes; R. H. Jones and W. W. Gerberich, eds . ; American Institute of

Mining, Metallurgical and Petroleum Engineers; New York, NY; 1986;

p 371-380.

Ricker, R. E. ; Duquette, D. J.; The role of hydrogen in corrosion

fatigue of high purity Al-Zn-Mg exposed to water vapor. Metall. Trans.

A; submitted 1987.

Ruff, A. W. ; Myshkin, N. K. ; Lubricated wear behavior and surface

active media effects of composition-modulated nickel -copper coatings on

steel. Journal of Tribology; submitted 1987.

Ruff, A. W. ; Standard practice for pin-on-disk wear testing of

materials. ASTM Committee G-2; Committee Draft submitted 1987.

Shen, M. C.; Cheng, H.; Peterson, M. B.; A computer analysis of

lubrication of dynamically loaded journal bearings including the effects

of asperity contacts. Transactions ASLE Meeting; Anaheim, CA; May 1987.

Sung, Pei; Fraker, Anna C.; Corrosion, repassivation and corrosion

fatigue behavior of the surgical implant alloy, Co-Cr-Mo. Environmental

Degradation of Engineering Materials; The Pennsylvania State University;

Vol. Ill; p 471-480; 1987.

Sung, Pei; Fraker, Anna C.; Corrosion and degradation of a polyurethane/Co-Ni-Cr-Mo pacemaker lead. Journal Applied Biomaterials;

December 1987; in press.

Swanson, P. A.; Ives, L. K. ; Whitenton, E. P. ; Peterson, M. B.;

A study of the galling of two steels using two test methods. Wear

of Materials - 1987; K. C. Ludema, ed. ; ASME; New York, NY; 1987;

p 49-58

Smith, J. H. ; Evaluation of cracking in aluminum cylinders. NBSIR-86-

3492; March 1987.

84
Smith, J. H. Evaluation of bolts. Special report to U.S. House of

Representatives Committee on Energy and Commerce; December 22, 1986.

Vasudevan, A. K. ; Liu, J.; Ricker, R. E.; Mechanism of stress corrosion

crack growth resistance of Al-Li-Cu alloys: role of grain boundary

precipitates. Environmental Degradation of Engineering Materials III; M.

R. Louthan, Jr., R. P. McNitt, and R. D. Sisson, Jr., eds.; The

Pennsylvania State University, University Park, PA; 1987; p 321.

Verink, E. D.; Kolts, J.; Rumble, J.; Ugiansky, G. M.; Corrosion data

program workshop summary. Materials Performance; Vol. 26; No. 4; 1987.

Whitenton, E. P.; Peterson, M. B„; Ives, L. K; Method for quantitative

measurement of galling damage. Metal Transfer and Galling in Metallic

Systems; AIME; New York, NY; 1987; in press.

Metallurgical Structure Group

Bennett, L. H. ; McAlister, A. J.; Vegard's law. Encyl. of Mat. Sci and

Eng.; Meyer, M. B. ; Editor; Pergamon Press, N. Y„; 1986; 52A1.

Burton, B. P.; Davidson, P. M.; Short-range order and frustration in

omphacite. Physics and Chemistry of Minerals; in press.

Burton, B. P. ; Davidson, P. M. ; Order-disorder in omphacite pyroxenes:

a model for coupled substitution in the point approximation. American

Mineralogist; 72; 337; 1987.

Burton B. P.; Reply to discussion of the above publication by R. E. Cohen; American Mineralogist; 1987; in press.

Burton, B. P.; Davidson, P. M.; Multicritical phase relations in

minerals. Advances in Physical Geochemistry. S. Ghose, Ed.; SpringerVerlag; in press.

Capobianco, C. B. ; Burton, B. P.; Davidson, P. M. ; Navrotsky, A.;

Structural and calorimetric studies of order-disorder in CdMgCCC^C^.

Journal of Solid State Chemistry; in press.

Clark, J. B.; Nayeb-Hashemi, A. A.; The Mg-Sc (magnesium-scandium)

system. Bull. Alloy Phase Diagrams 7(6); 514; 1986.

Clark, J. B. ; Nayeb-Hashemi, A. A.; The Be-Mg (beryllium-magnesium)

system. Bull Alloy Phase Diagrams 8(1); 57; 1987.

Clark, J. B. ; Nayeb-Hashemi, A. A.; The Ca-Mg (calcium-magnesium)

system. Bull. Alloy Phase Diagram 8(1); 58; 1987.

Clark, J. B. ; Nayeb-Hashemi, A. A.; The Mg-Po (magnesium-polonium)

system. Bull. Alloy Phase Diagrams 8(2); 116; 1987.

Clark, J, B.; Nayeb-Hashemi, A. A.; The Mg-Rh (magnesium- rhodium)

85
system. Bull. Alloy Phase Diagrams 8(2); 117; 1987.

Clark, J. B. ; Nayeb-Hashemi , A. A.; The Mg-Co (magnesium-cobalt ) system.

Bull. Alloy Phase Diagrams 8(4); 352; 1987.

Clark, J. B.; Nayeb-Hashemi, A. A.; The Ce-Mg ( cerium-magnesium) system.

Bull. Alloy Phase Diagrams; in press.

Clark, J. B. ; Nayeb-Hashemi, A. A.; The La-Mg (lanthanum-magnesium)

system. Bull. Alloy Phase Diagrams; in press.

Clark, J. B.; Nayeb-Hashemi, A. A.; The Nd-Mg (neodymium-magnesium)

system. Bull. Alloy Phase Diagrams; in press.

Kikuchi, R.; Burton, B. P. ; Calculation of some oxides using cluster

variation method. Physical B and C; in press.

McAlister, A. J.; The Al-Pd (aluminum- palladium) system. Bull. Alloy

Phase Diagrams 7(4); 368; 1986.

McAlister, A. J.; Bendersky, L. A.; Schaefer, R. J.; Biancanielo, F. S.;

Transformation of the icosahedral phase in rapidly quenched Al-rich Al-Mn

alloys. Scripta Met; 2J_; 103; 1987.

McAlister, A. J. ; Murray, J. L.; Schaefer, R. J.; Bendersky, L. A.;

Biancaniello, F. S.; Moffat, D. L. ; Stable and metastable equilibria in

the Al-Mn system. Met. Trans; 18A; 385; 1987.

McAlister, A. J.; The Al-Tl (aluminum- tellurium) system. Bull. Alloy

Phase Diagrams; in press.

McAlister, A. J.; The Ag-Al (silver-aluminum) system. Bull. Alloy Phase

Diagrams; in press.

McAlister, A. J.; The Al-Mn (aluminum-magnesium) system. Bull. Alloy

Phase Diagrams; in press.

Yoon, D. N. ; Shapiro, A. J.; Investigation of grain boundary migration

in ternary Mo-Ni alloys. 1987; submitted for publication.

Electrodeposition Group

Beauchamp, C. R.; Mathematical modeling of the deposition of alloys on moving fibers. Proc. 1987 AESF ; Chicago, IL; July 1987.

Goldman, A. I.; Long, G. G. ; Bennett, L. H. ; Lashmore, D. S.; Kuriyama,

M. ; Observations of two structurally distinct states in glassy Ni-P

using EXAFS; submitted J. Electrochem. Soc.; June 1987.

Johnson, C. E. ; Kelley, D. R. ; Mullen, J. L. ; Lashmore, D. C.; Chromium:

a wear resistant coating in the printing industry. Proc. of 1987 AESF

International Chromium Colloquium; San Diego, CA; in press.

86
Johnson, C. E. ; Kelley, D. R. ; Mullen, J. L. ; Lashmore, D. C.

;

Electrodeposition of wear resistant coatings. NBSIR; in press.

Lashmore, D. S.; Dariel, M. P. ; Electrodeposited Cu-Ni textured

super latt ices . J. of the Electrochem. Soc.; in press.

Stafford, G. R.; Turner, C.; The electrodeposition of aluminum from

molten salts. Proc. of 1987 AESF; Chicago, XL; July 1987.

Stafford, G. R.; The electrogenerative partial oxidation of propylene.

Electrochimica Acta, 32; 1137; 1987.

Nondestructive Characterization Group

Blendell, J. E.; Chiang, C. K. ; Freiman, S. W. ; Fuller, Jr., E. R.

;

Drescher-Krasicka, E.; Johnson, W. L. ; Ledbetter, H. M. ; Bennett, L. H.

;

Swartzendruber, L. J., Marinenko, R. B. ; Myklebust, R. L. ; Bright, D. S.;

Newbury, D. E,; Processing-property relations for Ba9YCu0y_ x high Tc superconductors. Advanced Ceramic Materials, 2 , No.3B; 512-529; July

1987.

Blendell, J. E. ; Chiang, C. K. ; Freiman, S. W.; Fuller, Jr., E. R.

;

Drescher-Krasicka, E. ; Johnson, W. L. ; Ledbetter, H. M. ; Bennett, L. H.

;

Swartzendruber, L. J. , Marinenko, R. B. ; Myklebust, R. L. ; Bright, D. S.;

Newbury, D. E. ; The relationship of electrical, magnetic, and mechanical

properties to processing in high Tc superconductors. American Chemical

Society Symposium Series, High Tc Superconductors; in press.

Clough, R. B.; Biancaniello, F. S.; Wadley, H. N. G. ; Measurement of

fiber fracture and fiber-matrix interface shear strengths in metal matrix

composites. Proc. of Conf. on Nondestructive Testing and Evaluation of

Advanced Materials and Composites; H. Mindlin et al. ed. , Battelle Mem.

Inst., Columbus, OH; 1987.

Clough, R. B.; Wadley, H. N. G.; Biancaniello, F. S.; Fracture

mechanisms in single crystal composites. J. Acoustic Emission, Vol J;

569; 1986.

Clough, R. B. ; The energetics of AE source characterization. Materials

Evaluation, Vol. 45; 556; 1987.

Clough, R. B.; Wadley, H. N. G. ; Mehrabian, R.; Acoustic emission

studies of electron beam surface modification of aluminum. Met. Trans B;

1987; in press.

Kahn, A. H.; Gefen, Y. ; Mester, M. L. ; Wadley, H. N. G. ; Eddy current

measurement of density during hot isostatic pressing. Review of Progress

in Quantitative NDE; Vol 7; D.O. Thompson and D.E. Chimenti, eds.; in

press

.

Kahn, A. H. ; Mester, M. L.; An eddy current system for the measurement

of aluminum rod during extrusion processing. Review of Progress in

Quantitative NDE; Williamsburg, VA. ; June 1987.

87
Linzer, M. ; Sato, T. ; Ikeda, 0.; Hatsuzawa, T,; Real-time evaluation of

wear particles using electromagnetic forced rotation and laser

scattering. Wear 115 : 273-284; 1987.

Norton, S. J.; Linzer, M. ; Backproj ection reconstruction of random

source distributions. J. Acoust. Soc. Amer. 81; 977-985; 1987.

Norton, S. J.; Three-dimensional seismic inversion of velocity and

density- dependent reflectivity. Geoph. J. Roy. Astr. Soc. 88; 393-415;

1987.

Norton, S. J.; Fast magnetic resonance imaging with simultaneously

oscillating and rotating field gradients. IEEE Trans. Med. Imaging MI-6;

21-31; 1987.

Norton, S. J.; Computing ray trajectories between two points: a solution

to the ray linking problem. J. Opt. Soc. Am.; in press,

Norton, S. J.; Mossbauer Imaging. NBS J. Research; in press.

Norton, S. J.; Mossbauer imaging. Nature; in press.

Norton, S. J.; Iterative siesmic inversion. Geophys . J. Roy. Astr,

Soc . ; in press

Norton, S. J.; Tomographic reconstruction of two-dimensional vector

fields: application to flow imaging. J. Acoust. Soc. Amer.; in press.

Simmons, J. A.; Turner, C. D.; Wadley, H. N. G.; Vector calibration of

ultrasonic and acoustic emission transducers. J. Acoust. Soc. Amer.; in

press

Wadley, H. N. G.; Simmons, J. A.; Microscopic origins of acoustic

emission. NDT Handbook, Vol. 5; P.M. McIntyre, ed. ; ASNT Press, Section

3; in press.

Wadley, H. N. G.; Simmons, J. A.; Drescher-Krasicka , E.; Rosen, M,

Clough, R. B.; Hsieh, T.; Hirschman, K. ; Biancaniello , F. S.; Composite

materials interface characterization. NBS Internal Report, in press.

Wadley, H. N. G.; Rogers, C. D.; Internal discontinuity sensor needs for

steel: Workshop proceedings; in press.

Wadley, H. N. G.; Interfaces: the next NDE challenge. Review of

Progress in QNDE , Vol. 7; D. 0. Thompson and D. E. Chimenti, eds . ; in

press

Wadley, H. N. G.; Cook, J. R. ; Ellerbrock, D. F. ; Dishun, T. R. ; Boyd, D. M. ; Hot charging and direct rolling of continuous cast steel: inprocess characterization and control. Proc . of Iron Making and Steel

Making Conference of the Iron and Steel Society of the AIME, March 29-

April 1, 1987; Pittsburgh, PA.

88
Wadley, H. N. G. ; Rath, B. B. ; Wolf; S. M.; Parrish, P. A.; eds.;

Proceedings of conference on intelligent processing of materials and

advanced sensors. 1987; in press.

Wadley, H. N. G.; Alers, G. A.; Noncontact ultrasonics applied to sensor needs for hot metal processing in the steel industry. Proc. of Conf. on Intelligent Processing of Materials and Advanced Sensors.

H. N. G. Wadley, B. B. Rath, S. M. Wolf, and P. A. Parrish, eds.; 1987;

in press.

Wadley, H. N. G. ; Rosen, M. ; Elkind B. J„; Ultrasonic sensor for

controlling surface modification. Proc. of Conf. on Intelligent

Processing of Materials and Advanced Sensors; H. N. G. Wadley,

B. B. Rath, S. M. Wolf, and P. A. Parrish, eds.; 1987; in press.

Wadley, H. N. G.; Alers, G. A. ; A pulsed laser/electromagnetic acoustic

transducer approach to ultrasonic sensor needs for steel processing.

Review of Progress in Quantitative NDE; 6A; 627; D. 0. Thompson and

D. E. Chimenti, eds.; Plenum Press; New York; 1987.

Wadley, H. N. G. ; Nature and characteristics of sensors for intelligent

processing of materials. J. of Metals; 30(10) ; 49-53; October 1986; and

in Proc. of Conf. on Intelligent Processing of Materials and Advanced

Sensors; H. N. G. Wadley, B. B. Rath, S. M. Wolf and P. A. Parrish, eds.;

1987; in press.

Magnetic Materials Group

Atzmony, U.; Swartzendruber , L. J.; Bennett, L. H. ; Dariel, M. P.

;

Lashmore, D. S.; Rubinstein, M. ; Lubitz, P.; Magnetization and magnetic

aftereffect in textured Ni/Cu compositionally-modulated alloys. J. Mag.

Magn. Mat Is.; in press.

Atzmony, U.; Norton, S. J.; Swartzendruber, L. J. and Bennett, L. H.

;

Mossbauer imaging: Experimental result. Nature; in press.

Bennett, L. H. ; Long, G. G. ; Kuriyama, M. and Goldman, A. I.; Local

atomic structure in transition metal/metalloid glasses: Ni-P. Structure

and Bonding in Noncrystalline Solids; G. E. Walrafen and A. K. Revesz

(Plenum Publishing Corporation, New York, 1986) p. 385.

Bennett, L. H. ; Kuriyama, M.; Long, G. G. ; Melamud, M. ; Watson, R. E. and

Weinert, M. ; Local atomic environments in periodic and aperiodic Al-Mn

alloys. Phys. Rev. B 34, 8270 (1986).

Bennett, L. H.; Lashmore, D. S.; Dariel, M. P.; Kaufman, M. J.;

Rubinstein, M.; Lubitz, P. ; Zadok, 0. and Yahalom, J.; Magnetic

properties of electrodeposited copper-nickel composition modulated

alloys. J. Mag. Magn. Matls. 67, 239 (1987).

Bennett, L. H. ; Cahn, J. W.; Schaefer, R. J.; Rubinstein, M. and

Stauss, G. H.; Icosahedral symmetry vs. local icosahedral symmetry in

Al-Mn alloys from NMR. Nature 326 , 372 (1987).

89
Bennett, L. H. and Watson, R. E.; Symmetry and supersymmetry in

crystals. Phys . Rev. B 35, 845 (1987).

Bennett, L. H. and Watson, R. E. ; Disclinations : Their relation to the

anisotropies of rare-earth hard magnets. Scripta Metall. 22, 573 (1987).

Dariel, M. ; Bennett, L. H. ; Lashmore, D. S.; Lubitz, P. ; Rubinstein, M.

Harford, M„ Z. ; Lechter, W. L. ; Properties of electro-deposited Co-Cu

Multilayers. J. Appl. Phys. 6.1, 4067 (1987).

Massalski, T. B.; Murray, J. L. ; Bennett, L. H. and Baker H., eds .

Binary alloy phase diagrams. American Society for Metals, Metals Park,

Ohio, 1986).

Melamud, M. ; Bennett, L. H. and Watson, R. E. ; Where are the iron atoms

and iron moments in RFen Al 12 - n

? A Wigner- Seitz analysis. J. Appl.

Phys

Melamud, M. ; Swartzendruber , L. J.; Bennett, L. H.; Cullen, J.;

Wun-Fogel, M. ; Moment distribution in amorphous magnetic ribbons. J.

Appl. Phys. 6_1, 3644 (1987).

61, 4246 (1987).

Moorjani, K. ; Bohandy, J.; Adrian, F. J.; Kim, B. F. ; Shull, R. D .

Chiang, C. K. ; Swartzendruber and Bennett, L. H.; Superconductivity in

bulk and thin films of Lax 85 Sr0 15 CuOA _ x and Ba2 YCu3 07

_ y

. Phys. Rev.

B 26, 4036 (1987)

Rubinstein, M. ; Bennett, L. H.; Chien, C. L. and Xiao, G.; Magnetism and

the observation of NMR lines in hexagonal Al A Mn and icosahedral Al-Mn

alloys. J. Appl. Phys. 21 4364 (1987).

Stauss, G. H. ; Rubinstein, M. ; Frieble, E. J.; Bennett, L. H. and

Schaefer, R. J.; Nuclear magnetic resonance powder patterns in Al6 Mn,

Al^Mn, and Al 12 Mn polycrystals. Phys. Rev. B 32, 2700 (1987).

Swartzendruber, L. J.; Bennett, L. H. and Ettedgui, H.; Initial

susceptibility studies of rapidly solidified Monel. Phys. 62, 3991

(1987)

Watson, R. E.; Melamud, M. and Bennett, L. H. ; Disclinations and

magnetism in rare earth- transition metal hard magnets. J. Appl. Phys.

61, 3580 (1987).

Wong-Ng, W. ; Roth, R. S.; Swartzendruber, L. J.; Bennett, L. H.;

Chiang, C. K. ; Beech, F. and Hubbard, C. R. ; X-Ray powder

characterization of Ba2 YCu3 07 _ x

. Advanced Ceramic Materials, 2 , 565

(1987)

90
INDUSTRIAL AND ACADEMIC INTERACTIONS

The research programs of the Metallurgy Division are designed and carried out

in support of industrial and scientific needs. Specialized facilities within

the Division, including metals processing and nondestructive evaluation,

attract scientists from both academic and industrial organizations for

cooperative research efforts. Interactions with industry, universities, and

professional organizations are viewed as an important element of our work

with collaborative programs, consulting and general involvement with outside

groups being a long standing practice. For example, the Metallurgy Division

has been working for more than 70 years with the steel industry to improve

the durability and performance of alloys.

In 1987, the Division performed collaborative research with many private

organizations through its Research Associate and Guest Scientist programs and

other arrangements. Representative examples of such interactions include:

INDUSTRY

1 . ALCOA

A cooperative program with the Alloy Technology Division of ALCOA

(Dr. A. K. Vasudevan) and the Corrosion and Wear Group of the

Metallurgy Division of NBS (R. Ricker) investigating the stress

corrosion cracking behavior of Al-Li and Al-Li-Cu alloys is in progress.

The objective of the first phase of this effort is to evaluate the

influence of grain boundary precipitate size distribution on the

intergranular stress corrosion cracking behavior of these alloys.

Samples with identical tensile properties but with the grain boundary

precipitate size distribution varying were prepared at ALCOA and tested

at NBS.

2 . ALCOA

Research has been published on the mechanism of dispersoid formation in

Al-Fe-Ni alloys. This research was initiated at the suggestion of

G. Hildeman of Alcoa and made use of information supplied by Alcoa.

3. Aluminum Association

The first phase of the cooperative project of NBS and the Aluminum

Association has been brought to a successful conclusion with the

execution of a plant demonstration of the eddy current sensor developed

for measuring temperature of extruded aluminum products during

processing. The Aluminum Association and NBS have agreed to continue

the project for a second year with the objectives of measuring

temperatures in more complex shapes and of obtaining information on the

non-uniformity of temperature profiles. Mr. Michael L. Mester will

continue as Research Associate for the Aluminum Association.

91
4. American Iron and Steel Institute

The Nondestructive Characterization Group has continued a strong

collaboration with the American Iron and Steel Institute (AISI) during

FY 87. The interaction began in 1983 with the signing of a memorandum

of understanding and agreement to research and develop ultrasonic

approaches for internal temperature distribution and pipe/porosity

sensors for control of steel processing. The work on the pipe/porosity

has essentially been completed with the. successful evaluation of a prototype system in FY 86. The sensor was the recipient of an IR-100

award in FY 87. Research continues with the temperature sensor toward

developing imaging approaches for solidifying bodies.

5. ASM International (American Society for Metals)

The technical activities of the joint NBS/American Society for Metals

Data Program for alloy phase diagrams are centered at NBS . The editor

and associate editor of the Bulletin of Alloy Phase Diagrams are

J. B. Clark and B. Burton (both of NBS). Three category editors of the

program are working at NBS: J. B. Clark, L. J. Swartzendruber and

A. J. McAlister, for Mg-, Fe- , and Al- alloys, respectively.

6. Battelle Columbus Laboratories

A joint activity is underway to prepare a wear atlas from selected

literature and research findings at Battelle Columbus Laboratories

and NBS. Battelle (W. Glaeser) and NBS (A. W. Ruff) are evaluating

250 publications in wear and friction to select authoritative findings

that relate wear and friction with material properties and surface

morphology. The findings will be published as an atlas under a co- operative effort that also includes the West German Bundesanstalt

fur Materialprufung.

7. Crucible Materials Corp., General Electric Co., and Hoeganaes Corp.

An industry-NBS consortium has been initiated to conduct research on automated measurement and control of powder particle size distributions

produced by atomization. Scientists from Crucible Materials, General

Electric, and Hoeganaes, which all are companies strongly interested in

control of rapidly-solidified alloy powders, are collaborating in this

consortium work with NBS scientists. In this research, the NBS

Metallurgy Division's high pressure inert gas atomization system is

being used to develop real-time measurements and feedback systems to

allow control of size distributions in atomized rapidly solidified

powder

.

92
8 . Deere and Company

A Research Associate Program with Deere and Company (P. A. Swanson)

and NBS (L. K„ Ives) is concerned with investigating problems connected

with the measurement of galling damage and the development of tests to

evaluate alloys used in agricultural and industrial equipment where

galling wear is a serious problem.

9. FIBA, Inc. and Union Carbide Corporation

A collaborative effort is underway between FIBA, Inc. (P. Horrigan)

,

Union Carbide Corporation (R. Tripolet) , and NBS ( J . H. Smith) to

evaluate use of acoustic emission techniques for use in the periodic

inspection of large steel pressure vessels. NBS is in the process of

developing specific procedures and test criteria to permit the use of

acoustic emission techniques for this application.

10. General Electric Company

A collaborative program with General Electric Company (D. Williams and

S. Miller) has been pursued to apply advanced photographic techniques to

study the break-up of molten alloys into fine droplets during gas

atomization.

11. Luxfer USA, Inc

A collaborative effort between NBS ( J . H. Smith) and Luxfer USA, Inc.

(G. Waite) is ongoing to determine the extent of cracking in seamless

aluminum compressed gas cylinders and to develop a reliable test method

for inspecting the cylinders in service.

12. Martin Marietta Corporation

Ward L. Johnson and Haydn N. G. Wadley are collaborating with John

Ahearn at Martin Marietta to explore the possibility of detecting

threading misfit dislocations at Si-GaAs thin film interfaces using

internal friction methods. If successful, it will be considered as a potential sensor approach for controlling interfacial dislocations

during molecular beam epitaxy of thin film compound semiconductors on silicon substrates.

13. National Association of Corrosion Engineers (NACE)

The NACE-NBS Corrosion Data Center at NBS (D. Anderson) continues to

provide the scientific and technical coordination to the joint program

initiated in 1985. The program objective is to collect, evaluate and

disseminate corrosion data on engineering materials in computerized

format. NACE has assigned two full time Research Associates to support

the data center activities. Program tasks are aimed at producing PC

software for distribution by NACE. Two software programs have been

completed, both based on extensive NACE data surveys. Additional

software development programs relate to economics of material selection

93
for corrosive environments and corrosion thermodynamics. The program is

structuring a central data base for compilation of numerical data from a variety of sources which, in turn, will serve as basis for distributed

programs emphasizing specific environments, materials and applications.*

The program is being enhanced by a new activity to introduce expert

system concepts.

14. National Physical Laboratory, Delhi, India - S. P. Singhal

Roger B. Clough established a three year collaborative effort on measuring AE spectra from composite failure.

15. Union Carbide Corporation and Taylor-Wharton , Inc.

A collaborative effort is underway between the Linde Division of Union

Carbide Corporation (M. Rana) , Taylor-Wharton, Inc. (K. Miller), and the

Corrosion and Wear Group ( J . H. Smith) to develop criteria for the safe

design and fabrication of high strength steel, seamless pressure

vessels. Criteria have been developed, based on fracture mechanics

principles, to permit the use of new, higher strength steels for the

construction of pressure vessels without reducing the level of safety

of these vessels.

16. Welding Research Council (WRC)

An interpretive report for the Pressure Vessel Research Committee

on Effects of Hydrogen in Steels is being prepared by C.G, Interrante

of NBS for publication as a WRC Bulletin.

17. Zimmer Company

A collaborative study with Zimmer Company, Warsaw, Indiana was carried

out by Anna C. Fraker to determine mechanical properties of the surgical

implant alloy, Ti-6Al-4V. Transmission electron microscopy was conducted to investigate microstructural changes caused by small

variations in oxygen content and other minor compositional constituents.

INDUSTRY /UNIVERSITY

1. BHABHA Atomic Research Center (Government of India)

University of Poona/University of Roorkee

A cooperative project is underway with the BHABHA Atomic Research Center

(Dr. C. K. Gupta), the University of Poona (Dr. A. P. B. Sinha) and the

University of Roorkee (Dr. M. L. Mehta). This project is part of the

Indo-US Physical, Materials and Marine Sciences Collaboration Program

and the objective of this project is to study the influence of nitrogen

content on the stress corrosion cracking behavior of stainless steels

(alloy 316L) . NBS has provided material for this study and complimentary experiments will be conducted at the various institutions.

94
2. National Bureau of Standards Metals Processing Laboratory

The Metals Processing Laboratory of the National Bureau of Standards

contains facilities for preparation of special samples not readily

obtainable elsewhere. Scientists from industry and universities can

come to NBS to help prepare samples for independent or collaborative

research. During the past year investigators from Cominco, Metcut,

Lockheed, Bureau of Mines, Air Force Materials Laboratory, Johns Hopkins

University, University of California, and University of Wisconsin have

participated in interactions in this program.

3. Rhone Poulenc, Inc . /University of Lyon, France

Under the sponsorship of the French company Rhone Poulenc, Inc., and in

cooperation with the University of Lyon (Professor Mazille) , a French

graduate student (R. Rothea) spent sixteen months at NBS to study the use of acoustic emission to detect, and possibly identify, different

corrosion and stress corrosion processes on stainless steels.

UNIVERSITIES

1.

Applied Physics Laboratory, The Johns Hopkins University

A collaborative effort is underway between the Applied Physics

Laboratory of the Johns Hopkins University (K. Moorjani) and NBS

(R. Shull) to prepare and investigate the magnetic behavior of composite

materials having nanocrystalline-sized grains.

2. Cornell University

Roger B. Clough is discussing collaborative effort with Prof.

S. L. Phoenix on statistical analysis of fiber composite failure.

3. Iowa State University

Theoretical work on the inclusion of non-equilibrium interface

conditions into alloy dendritic growth theory has been published in

collaboration with Professor R. Trivedi of Iowa State University.

4. Johns Hopkins University

Studies on the mechanism of transgranular stress corrosion cracking

are being pursued in cooperation with Johns Hopkins University

(Dr. J. Kruger). The experimental part is being carried out at NBS by

a graduate student (T. Cassagne) , and the staff of the Corrosion and

Wear Group is involved both in the experiment and in the analysis of the

results

.

95
5. Johns Hopkins University

A collaborative effort with Johns Hopkins University (D. Shechtman)

which resulted in the discovery of an entirely new class of materials,

quasicrystals, is continuing in order to investigate the processing

conditions which produce these special alloys.

6. Rensselaer Polytechnic Institute

A joint research program on interface interactions in Si-Ge multilayers

has been initiated with K. Raj an of Rensselaer Polytechnic Institute.

The effects of stresses at sharp interfaces is being investigated for

applications to composite systems.

7. University of Maryland

The University of Maryland (R. W. Armstrong) and NBS (R. Polvani)

have collaborated on a study of ignition of energetic materials.

Theory can be used to show dislocation motion is a likely cause for

"hot spot" formation and subsequent ignition. However, the competition

between plasticity and cleavage deformation that occurs in RDX, a typical energetic material, is a major complication for this theory.

The NBS Dynamic Microindentation Instrument is a tool uniquely suited

for studying the effect of load and rate on the location of the ductile

brittle transition in RDX type materials.

8. University of Wisconsin at Madison

Collaboration with Professor J. Perepezko (U. of Wisconsin) and his

graduate students has resulted in the publication of two scientific

papers on microstructure development in TiAl and the thermal

decomposition of quasicrystals in Al-Mn alloys.

96
TECHNICAL/PROFESSIONAL COMMITTEE LEADERSHIP ACTIVITIES

ACTIS Technical Advisory Committee

M. B. Peterson

American Association for Crystal Growth

S. R. Coriell, Executive Committee

American Electroplaters Society

Alloy Deposition Handbook

D. S. Lashmore , Editor

American Institute of Mining, Metallurgical and Petroleum Engineers

The Metallurgical Society

J. B, Clark, The Physical Metallurgy Committee

J. B. Clark, The Physics and Chemistry of Materials Committee

R. Ricker, Committee on Corrosion and Environmental Effects

American Society for Metals (ASM International)

Materials Science Division

R. Ricker, Committee on Corrosion and Environmental Effects

NDT Committee

H. N. G. Wadley

Subcommittee on Metallurgical Reactions and Electromigration in

Electronic Devices

C. A. Handwerker, Chairman

Washington, DC Chapter - Executive Committee

R. Ricker, Chairman, Educational Committee

A. W. Ruff, Chairman, Program Committee

American Society for Testing and Materials

B7 : Light Metals and Alloys; Aluminum Alloy Ingots and

Castings

R7.07.09: Conversion Coatings on Aluminum

D . S . Lashmore , Chairman

B8 : Electrodeposited Coatings

B8.01: Terminology, Editing Public Relations and Metrication

WG.05: D. S. Lashmore, Metrication Chairman

B8 „ 06

Chemical Conversion Coatings

D, S. Lashmore, Subcommittee Chairman

B8, 10.03: General Test Methods for Microhardness

C. E. Johnson, Liaison to E04

E3 : Chemical Analysis of Metals

E3.07: Acoustic Emission

R. C. Clough

97
E7

:

Nondestructive Testing

Joint Task Group on Acoustic Emission; System Calibration

J. A. Simmons, Chairman

E24

:

Fracture Testing

C. G. Interrante, Member of Executive Committee

E24.05: Terminology for Fracture Testing

C. G. Interrante, Co-Chairman

E49

E49.02.5:

Computerization of Material Property Data

Corrosion Data Formats

D. B. Anderson, Chairman

F4

:

F4.G1

:

Medical and Surgical Materials and Devices

Joint Section on Corrosion of Implants

A. C. Fraker, Co-Chairperson

F7

:

F7 . 04

:

Aerospace Industry Methods

Hydrogen Embrittlement Testing

C. G. Interrante, Chairman, Task Group on Terminology

G1

:

Corrosion of Metals

D. B. Anderson, Liason to ASTM Committee E-49

Gl.03.1: Corrosion Data Formats Task Group

D. B. Anderson, Chairman

G1.06: SCC and Corrosion Fatigue

R. Ricker

G1.10: Corrosion of Metals in Soil

E. Escalante

Gl.10.1 Measurement of pH of Soil

E. Escalante, Task Group Leader

G1 .10.2: Measurement of Soil Resistivity

E. Escalante

Gl.ll: Electrochemical Measurements in Corrosion

R. Ricker

Gl . 14: Corrosion of Steel in Concrete

E. Escalante

G2

:

G2.2:

Erosion and Wear

Solid Particle Erosion

A. W. Ruff, Task Group Leader

G2.9: Executive Subcommittee Task Group on Operations

A. W. Ruff, Chairman

98
ASTM Committee on Light Metals

R. D. Shull, Member

W . J„ Boettinger, Member

ASTM Committee on Nondestructive Testing

L. J. Swartzendruber , Member

L„ H. Bennett, Member

ASTM Standing Committee on Terminology

C. G. Interrante, Technical Committee Representative

ASM INTERNATIONAL

Alloy Phase Diagram Data Committee

J. B. Clark, Chairman

Materials Science Division Council

J. B. Clark

American Institute of Mining, Metallurgical and Petroleum Engineers

The Metallurgical Society

J. B. Clark, The Physical Metallurgy Committee

J. B. Clark, The Physics and Chemistry of Materials Committee

American Society of Mechanical Engineers

Tribology Division, Executive Committee

A. W. Ruff

Research Committee on Tribology

M. B. Peterson, Chairman

A. W. Ruff

Wear of Materials Conference Steering Committee

A. W. Ruff

Department of Energy ECUT Tribology Program

M. B. Peterson, Chairman, Advisory Panel

Electrochemical Society

Editorial Committee

U. Bertocci, Division Editor

Electrodeposition Division

D„ S. Lashmore , Secretary-Treasurer

Industrial Electrolytic Division

D. E. Hall, Executive Committee

Publicity Committee

D. E. Hall

Sensors Symposium Organizing Committee

D. E. Hall

99
Federation of Materials Societies

S. R. Corieil, Trustee

Instrument Society of America

S. J. Norton, Session Organizer, 1986 Annual International Meeting

International Advisory Committee and Program Committee for International

Conference on Rapidly Quenched Metals

W. J. Boettinger, Member

International Institute for the Science of Sintering

P. W. Voorhees, Corresponding Member

International Organization for Standardization

TC164: Mechanical Testing

1 . Terminology

C. G. Interrante, Delegate

International Standards Organization

TC107: Metallic and Other Non-Organic Coatings

C. E. Johnson, Delegate

D. S. Lashmore , Delegate

2: Methods of Inspection and Coordination of Test

Methods

C. E. Johnson, Delegate

D. S. Lashmore, Delegate

3: Electrodeposited Coatings and Related Finishes

C. E. Johnson, Delegate

D. S. Lashmore, Delegate

Maryland Institute of Metals

W. J. Boettinger, Executive Board Member

Materials Science and Engineering

L. H. Bennett, Associate Editor

National Association of Corrosion Engineers (NACE)

Baltimore -Washington Chapter Executive Committee

R. Ricker, Membership Committee Chairman

Corrosion '86 Symposium on New Electrochemical Techniques

R. Ricker, Reviewer

CORROSION - The Journal of Science and Engineering

R. Ricker, Journal Reviewer

Review Board for the Journal: Materials Performance

R. Ricker

T. l Corrosion Control in Petroleum Production

T.1D Corrosion Control by Chemical Treatment

R. Ricker, Unit Committee

100
T.1D.26 The Role of Bacteria in Corrosion

R. Ricker, Task Group

T. 3

T . 3E

Corrosion Science and Technology Committee

R„ Ricker, Unit Committee on SCC and Corrosion Fatigue

T„3K Corrosion and Other Deterioration Phenomenon Associated

with Concrete

E. Escalante

T.3L R. Ricker, Unit Committee on Electrochemical Techniques

T.3.2 Formats for Computerized Corrosion Information

D. B. Anderson, Chairman

1986 Conference on Magnetism and Magnetic Materials

L. H. Bennett, Member, Local committee

L. H. Bennett, Local Treasurer

National Research Council

Transportation Research Board Evaluating Corrosion Effects in

Steel Bridges

E. Escalante, Panel Member

Office of Energy-Related Inventions, National Bureau of Standards

L„ H„ Bennett, Reviewer of Invention Disclosures

J. H. Smith, Reviewer of Invention Disclosures

Read Research Conferences

Organizing Committee

D. S. Lashmore , Member

Society for Automotive Engineers

Committee on Automotive Trim

D„ S. Lashmore, Invited Member

Society for Biomaterials Standards

A„ C. Fraker, Chairperson, Representative

Society of Automotive Engineers/American Society of Testing and Materials

Unified Numbering System for Metals and Alloys

L. H. Bennett, NBS Representative

Versailles Advanced Materials and Standards

Subcommittee on Wear

A. W. Ruff, U.S. Representative

101
EXTERNAL RECOGNITION AND AWARDS

M. P. Peterson; 1987 Mayo D. Hersey Award of the American Society for

Mechanical Engineers

M. Linzer and H. N. G. Wadley: IR-100 Award for "Ultrasonic Pipe Porosity

Sensor"

102
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BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

2o Performing Organ. Report No. 3. Publication Date

NBSIR 87-3615 October 1987

4. TITLE AND SUBTITLE

Metallurgy Division Annual Report 1987

NBSIR 87-3615

5. AUTHOR(S)

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

7. Contract/Grant No,

8. Type of Report & Period Covered

9* SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street* City, State, ZIP

)

10. SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information . If document includes a significant

bibliography or literature survey, mention it here) This report summarizes the FY 1987 activities of the Metallurgy Division of the

National Bureau of Standards. The research centers upon the structure-processingproperties relations of metals and includes alloys- and on the methods of their

measurement. The activities also include the generation and evaluation of critical

materials data. Efforts comprise studies of metallurgical processing, corrosion and

wear, chemical metallurgy, electrodeposition, nondestructive characterization and

magnetic materials.

The work described also includes three cooperative programs with American professional

societies and industry: the American Society for Metals (ASM) - NBS Alloy Phase

Diagram Program, the National Association of Corrosion Engineers (NACE) - NBS

Corrosion Data Program, the American Iron and Steel Institute (AISI) - NBS Steel

Sensor Program, and the Aluminum Association.

Work in support of other government agencies includes a major program to assist the

Nuclear Regulatory Commission in addressing the critical national problem of disposing

of high level nuclear waste in geologic repositories.

The scientific publications, committee participation, and other professional interactions of the 72 full-time and part-time permanent members of the Metallurgy Division

and its 40 guest researchers are identified

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Annual report; industrial interactions; Metallurgy Division; metals, publications;

technical activities

13. AVAILABILITY

| | Unlimited

| | For Official Distribution. Do Not Release to NTIS

1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

[Xj Order From National Technical Information Service (NTIS), Springfield, VA„ 22161

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PRINTED PAGES

107

15. Price

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