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i QC100 .U56 NO.86-3438 1986 V19 C.1 NBS-P NBS

PUBLICATIONS

Institute for Materials Science and Engineering

MEnmincY

-ocinn

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86 - 3^38

1986

Technical Activities

1986
Topography of a severely worn, galled steel surface acquired and

plotted with a computerized surface profiling system.

Computer graphics by E. Whitenton
ms

RESEARCH

INFORMATION CENTE^o

IMSE — - : l a Cl

Institute for Materials Science and Engineering \\p METALLURGY

E.N. Pugh, Chief

J.G. Early, Deputy

NBSIR 86-3438

U.S. Department of Commerce

National Bureau of Standards

Technical Activities

1986
METALLURGY DIVISION

CHIEF

E. Neville Pugh

Phone: (301) 975-5960

DEPUTY CHIEF

James G. Early

Phone: (301) 975-5961

GROUP LEADERS

Structure Characterization

Masao Kuriyama

Phone: (301) 975-5974

Metallurgical Processing

John R. Manning

Phone: (301) 975-6157

Wear and Mechanical Properties

Arthur W. Ruff

Phone: (301) 975-6010

Chemical Metallurgy

John B. Clark

Phone: (301) 975-6040

Corrosion

U. Bertocci (Acting)

Phone: (301) 975-6017

Electrodeposition

David S. Lashmore

Phone: (301) 975-6405

Nondestructive Characterization

Haydn N. G. Wadley

Phone: (301) 975-6140

ii
ABSTRACT

This report summarizes the FY 1986 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 synchrotron radiation research for

materials characterization, metallurgical processing, wear and

mechanical properties, chemical metallurgy, corrosion and protection

of metals, 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, and the American Iron and Steel Institute (AISI) - NBS

Steel 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. Another example described is the

use of advanced electrodeposition technique to assist the Bureau of

Engraving and Printing in the development of wear resistant chromium

coatings for currency printing plates.

The scientific publications, committee participation, and other

professional interactions of the 86 full-time and part-time

permanent members of the Metallurgy Division and its 70 guest

researchers are identified.

iii
,

.

'
TABLE OF CONTENTS

PAGE

OVERVIEW ...... 1

METALLURGY DIVISION

ORGANIZATIONAL CHART ...... 5

RESEARCH STAFF . ..... 6

TECHNICAL ACTIVITIES

Structure Characterization ... .13

Metallurgical Processing ...... 19

Wear and Mechanical Properties .............. 29

Chemical Metallurgy 37

Corrosion and Protection of Metals ............ 43

Electrodeposition 49

Nondestructive Characterization ....... . . 59

Magnetic Properties ............. .71

OUTPUTS / INTERACTIONS

Recent Publications .................... 73

Industrial and Academic Interactions 85

Technical/Professional Committee

Leadership Activities 93

APPENDIX

Organizational Chart

National Bureau of Standards A1

Organizational Chart

Institute for Materials Science and Engineering A2

v

OVERVIEW

METALLURGY DIVISION (450)

E. Neville Pugh, Chief

James G. Early, 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. 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 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 seven

groups

The area of measurement was highlighted by activities of the Structure

Characterization Group at the National Synchrotron Light Source at

Brookhaven. FY86 was the first full year of operation of the IMSE beamlines

and a number of experiments were conducted, including the implementation of a tunable x-ray image magnifier to study the microstructures of several high

technology materials, and measurement of near edge and extended fine

structure using Raman EXAFS. Another significant development during FY85 was

the initiation of a cooperative program between the Corrosion and

Nondestructive Evaluation Groups to measure and analyze acoustic emission

(AE) during the propagation of stress corrosion cracks in austenitic

stainless steels; in addition to providing mechanistic insight into the

stress corrosion process, the AE technique is a potentially valuable method

of monitoring critical structures for the occurrence of this dangerous type

of failure.

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

activities in FY86. In the Alloy Phase Diagram Data Program, set up

cooperatively with the American Society for Metals (ASM) to provide

critically evaluated phase diagrams, the year was highlighted by the

completion of digitization of over 1500 binary diagrams for the new ASM book

which updates Hansen's classical compilation. In addition, the task of

entering graphical and numerical information for binary systems into a computerized on-line database is well underway, and a meeting to obtain input

from potential users proved highly successful. The evaluation of ternary Albased (Al-Cu-X) systems has been initiated, and software used in the binary

program has been extended to ternary applications. The focus of activities

in the National Association of Corrosion Engineers (NACE)-NBS Corrosion Data

Center has been in two areas: completion of the computer-encoding of NACE's

1
Corrosion Data Survey-Metals, resulting in the issue of a floppy disc

package, and the acquisition of industrial corrosion databases. The Wear and

Mechanical Properties Group organized a workshop at NBS to evaluate needs in

the tribology data and information area; a report containing specific

recommendations was prepared, and some of the efforts are now underway.

As indicated above, our research programs are moving increasingly to address

the science underlying materials processing, and are leading to more direct

interaction with industry. The work on process sensors being carried out in

the Nondestructive Characterization Group is a prime example of this trend.

In a collaborative effort with the American Iron and Steel Institute, a program in which ultrasonic time of flight tomography is being used to

measure internal temperature distribution in hot steel bodies has continued

to make significant progress and is now being extended from solid to

partially solidified material. In FY86, a similar program has been initiated

with the Aluminum Association to investigate the use of an eddy current

approach in the measurement of internal temperatures during the extrusion of

aluminum. Another major activity centers on the production of powders by

means of high pressure inert gas atomization, an important method for the

production of rapidly solidified materials. This activity, centered in the

Metallurgical Processing Group, has already led to considerable interaction

with various industrial laboratories, and discussions are in progress to

build a cooperative program around the full scale atomizer which has been

assembled in the group. The immediate challenge is to reproducibly produce

powders of the desired size (and hence properties), and the thrust of the

proposed consortium is the development of sensors and an automated process

control system.

Metal matrix composites represent another 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. Our

approach is unusual in that the alloy is electrodeposited 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. In other groups, the interfaces are being

characterized by means of ultrasonic (Nondestructive Characterization) and

microhardness (Wear and Mechanical Properties) techniques; thermodynamic

modeling of stresses generated by interdiffusion at the interface are being

conducted in the Metallurgical Processing Group.

A broad range of activities involving other government agencies was conducted

in FY86, 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

quasicrystals and rapid solidification under Defense Advanced Research

Projects Agency support. An example of the latter 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

2
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 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 86 full-time and part-time permanent people. In addition, there

were 70 guest researchers and research associates in residence during the

past year who collaborated with Division scientists.

3

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RESEARCH STAFF

Structure Characterization Group

Black, David R. o Inelastic x-ray scattering

o Energy dispersive x-ray diffraction

o X-ray optics

Burdette, Harold E. o X-ray optics engineering

o Crystal growth

o Instrumentation

Dobbyn, Ronald C. o X-ray dynamic imaging

o X-ray optics

o Synchrotron radiation instrumentation

Kuriyama, Masao o Scattering physics

o Solid state physics

o Crystallography

Long, Gabrielle G. o X-ray scattering physics

o X-ray absorption spectroscopy

o Disordered materials

Spal, Richard D. o X-ray imaging

o X-ray optics

o Instrumentation

Metallurgical Processing Group

Biancaniello, Francis S. o Special alloy and quasicrystal preparation

o Melt-spinning rapid solidification

o Inert gas atomization and metal powder

processing

Boettinger, William J. o Rapid solidification

o Alloy microstructural characterization

o Relation of alloy microstructures to

processing conditions

Coriell, Sam R. o Modeling of solidification processes

o Interface stability

o Convection and alloy segregation during

solidification

Handwerker, Carol A. o Interface studies

o Diffusion- induced grain boundary migration

o Liquid film migration

)

6
Hardy, Stephen C. o Alloy coarsening

o Surface tension measurements

o Interface segregation

Manning, John R. o Metallurgical processing

o Diffusion kinetics

o Interface migration

Parker, Robert L. o Ultrasonic measurement of solid/ liquid

interface, interface kinetics

o Applications to alloys, casting,

metallography, rapid solidification

Ridder, Stephen D. o Microparticle rapid solidification

o Solidification dynamics

o Inert gas atomization

Rottman, Craig A. o Structure and properties of interfaces

o Phase transformations

o Statistical mechanics

Schaefer, Robert J. o Quasicrystals

o Electron beam rapid solidification

o Convection and interface effects during

solidification

Voorhees, Peter W. o Coarsening phenomena

o Elastic effects during phase

transformations

o Anisotropic interface effects

Wear and Mechanical Properties Group

Blau, Peter J. o Friction and wear transitions

o Wear microstructure relations

o Microindentation and scratch hardness

Fraker, Anna C. o Titanium alloys

o Corrosion processes

o Transmission electron microscopy

o Surgical implant metals

Harris, Jonice S. o Scanning electron microscopy

o Fatigue properties measurements

o Wear and friction properties

Ives, Lewis K. o Wear of metals

o Transmission electron microscopy

o Erosion of metals

7
Peterson, Marshall B. o Wear of metals

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

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

Chemical Metallurgy 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

Kahan, Daniel J. o Evaluation of binary alloy phase diagrams

o Prepare computer graphics for phase

diagrams

o Respond to technical inquiries

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

Murray, Joanne L. o Thermodynamic modeling of alloy phase

diagrams

o Data evaluation for Ti and Al-based alloy

systems

o Editor, Bulletin of Alloy Phase Diagrams

and Constitution of Binary Alloys

o Computer database development for alloy

phase diagrams

Swartzendruber , Lydon J. o Magnetic methods, NDE

o Gamma-ray resonance spectroscopy

o Iron binary phase diagrams

8
Corrosion Group

Anderson, David B.

Bertocci, Ugo

Escalante, Edward

Harrison, Steve

Interrante, Charles G.

Kaufman, Michael J.

Ricker, Richard E.

Shull, Robert D.

Stoudt, Mark R.

Ugiansky, Gilbert M.

Van Orden, Ann C.

o Industrial corrosion testing

o Corrosion data evaluation

o Corrosion database development

o Electrochemical measurements

o Computer modeling

o Passivity and pitting

o Underground corrosion

o Corrosion in concrete

o Corrosion rate measurements

o Computer systems programming

o Software engineering

o Laboratory automation

o Hydrogen embrittlement

o Nuclear waste disposal

o Environmental testing

o Physical Metallurgy

o Electron Microscopy

o Stress Corrosion Cracking

o Environmental induced fracture

o Corrosion and electrochemistry

o Scanning and transmission electron

microscopy

o X-ray and neutron diffraction

o Rapid solidification

o Differential thermal analysis

o Scanning electron microscopy

o Physical metallurgy

o Corrosion testing

o Environmentally induced fracture

o Management of computer database for

corrosion data

o Corrosion data evaluation and

dissemination

o Localized corrosion

o Slow strain rate stress corrosion testing

o Marine corrosion

o Localized corrosion

o Dealloying

9
Electrodeposition Group

Beauchamp, Carlos R. o Computer simulation of electrodeposition

processes

o Electrochemical measurements of kinetic

parameters

o Corrosion measurements of electrodeposited

coatings

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

Johnson, Christian E. o Ultra-black coatings

o Electroless deposition processes

o Metallic glass alloy deposition

o Microhardness SRM research

Kelley, David R. o Microhardness SRM development

o Dye penetrant SRM development

o Precious metal electrodeposition

Lashmore, David S. 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

Mullen, Jasper L. o Development of automated hardness testing

o Electrochemical measurements for

determining metal corrosion

o Analytical spectroscopy

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

10
Linzer, Melvin

Mauer, Floyd A.

Norton, Stephen J.

Simmons, John A.

Wadley, Haydn N.G.

Microscopy

Olson, Craig D.

Shapiro, Alexander J.

Magnetic Properties

o Electromagnetic theory

o Solid state physics

o Ultrasonic imaging

o Acoustic emission

o Ultrasonic scattering

o Ultrasonic tomography

o X-ray diffraction

o Ultrasound-microstructure relations

o Ultrasonic imaging

o Inverse modeling

o Dimensional resonance tomography

o Dislocation theory

o Acoustic emission

o Inverse modeling

o Dislocations and fracture

o Acoustic emission

o Ultrasonics

o Scanning electron microscopy

o X-ray microanalysis

o Thermal wave microscopy

o Analytical electromicroscopy

o X-ray microanalysis

o Image analysis

o Magnetic measurements

o Alloy phase stability

o Hyperfine fields

Bennett, Lawrence H.
P
ADVANCED MICROSTRUCTURE CHARACTERIZATION AND SYNCHROTRON RADIATION

RESEARCH FOR MATERIALS SCIENCE Gabrielle Long and Masao Kuriyama

The emergence of nontraditional materials and intensive materials

engineering necessitates new approaches to materials characterization and

quality control. Often the properties of these new high technology materials depend critically on subtle differences in chemistry and microstructure. The objectives of these tasks are to address this challenge through

the development of x-ray measurement methods and standards for the advanced microstructure characterization of metallurgical microstructures

and other high technology materials, and to perform these measurements in

real time. The research has included structural determination of disordered materials and ultra-thin films, the nondestructive evaluation of

imperfections and strains in materials, the microstructure characterization of high technology single crystals, ultrasensitive trace element

detection, and even the study of structural features in human teeth.

These tasks are directly related to the synchrotron radiation program in

the Institute for Materials Science and Engineering (IMSE), which was initiated in FY80. The Office of Nondestructive Evaluation in IMSE contributed to the support of this effort in the areas of data processing and

image detector development for real time observations. The IMSE synchrotron radiation program is the materials science part of the joint effort

between the Naval Research Laboratory (NRL) and the National Bureau of

Standards (NBS) to establish and operate a synchrotron radiation facility

for NRL and NBS scientists at the National Synchrotron Light Source

(NSLS), Brookhaven, NY. In FY86, NBS completed the first year of experimental operations and instrument evaluation at the IMSE x-ray beamline at

NSLS.

FY86 Significant Accomplishments

o This was the first full year of operation of the IMSE synchrotron

radiation beamlines for scientists from NBS, NRL, and from government, industry and universities.

o A tunable x-ray image magnifier, covering the energy range 8-30 keV

was constructed, tested, and implemented for the real time observation of microstructures.

o Detailed microstructural measurements were carried out, as a function of incident photon energy, on several high technology

materials of high current interest.

o Near edge and extended fine structure measured using x-ray Raman

EXAFS were analyzed.

o Near neighbor environments for atoms in icosahedral phase aluminummanganese were calculated.

o Progress was made on the construction of an innovative x-ray camera

based on a CCD sensor.

13
Operation of the NBS/IMSE X-23A Beamline at NSLS

Subtask 1

R. Dobbyn, D. Black, R. Spal, H. Burdette, G. Long and M. Kuriyama

The Structure Characterization and Synchrotron Radiation Group at NBS has

completed the first year of experimental operations and instrument

evaluation on the IMSE x-ray beamline at the NSLS in Brookhaven, NY. The

beamline offers materials scientists from NBS, NRL and other government

laboratories, as well as from industry and from universities, a research

tool combining the highest brightness, lowest emittance source of x-rays

in the world with high resolution x-ray optics for characterizing the

microstructures of materials. It enables researchers to conduct real-time

in-situ measurements on a micrometer scale.

The x-ray storage ring at NSLS was operated for most of this year at an energy of 2.5 GeV with electron currents starting as high as 160 mA and

decaying to 30-40 mA before reinjection. Beam lifetimes were often 4 to 5

hours and occasionally as good as 7 hours. There were two shutdowns, each

of approximately one month duration, for repairs and replacement of

critical instrumentation in the ring. At present, the source is operating

at the design energy and about one- third the design current, with the

excellent brightness and low emittance that was predicted.

Scientists from the group used this time to perform energy dependent x-ray

topography research on high technology single crystals and to commission

new instrumentation and perform first experiments using these enhanced

capabilities. A tunable x-ray image magnifier for providing magnified

diffraction and microradiographic images was installed. This new magnifier is tunable over the energy range 8-30 keV and can be used to extend

the spatial resolution of two-dimensional x-ray detectors (such as video

or film) by one to two orders of magnitude with the goal being submicrometer resolution.

Since the beamline can receive white radiation as well as monochromatic

x-rays, scientists from the this group used the opportunity to install instrumentation for energy dispersive x-ray diffraction. The probe volume

(0.1 X 1.0 X 1.0 mm^) is more than two orders of magnitude smaller than

that achieved in the laboratory and the data acquisition time is reduced

by at least a factor of 30. Diffraction peaks up to 60 keV are seen. Experiments have been performed on a cylindrical sample with a known

strain distribution. The radial and tangential components were measured

and found to agree well with theory.

Scientists from this group, in collaboration with a scientist from the

Analytical Chemistry Division, have established a high-sensitivity trace

element detection capability using the high brightness, energy tunability

and polarization of synchrotron radiation together with grazing incidence

reflection techniques. In the synchrotron radiation experiment, scattered

radiation can be greatly reduced by effective utilization of polarization,

thereby substantially increasing the fraction of fluorescence signal and

bringing about a significant reduction in the minimum detectability limit.

14
The tuning capabilities of the monochromator were expanded to include a scanning feature applicable to performing absorption spectroscopy and

Extended X-ray Absorption Fine Structure (EXAFS) experiments. Measurements have been made on iron-chromium alloys and their oxides, icosahedral phase aluminum-manganese, and thin film yttria and zironia.

X-ray Image Magnification Using Hard Radiation

Subtask 2

R. C. Dobbyn, D. R. Black, and M. Kuriyama

A tunable x-ray image magnifier, has been implemented for the real time

observation of microstructures at the IMSE x-ray beamline at NSLS. Early

results on magnified diffraction topographs of VLSI devices on silicon and

magnified microradiographs of crack specimens have demonstrated the real

time applicability of this method.

High resolution, image-magnified x-ray microradiographs of dental specimens [1] have been obtained over a range of x-ray energies from 8 to 19

keV. Earlier work, [2] using 8 keV x-rays and 22x image magnification

showed detailed structural features such as prism lines, lines of Retzins

and cross-striations with some images as small as one micrometer. The

present magnification technique was used with varying photon energies to

enhance the structural details and to enable quantitative image analysis.

Microradiographs of tooth specimens up to 1 mm thick were obtained, as well as a microradiograph of a tooth specimen immersed in a demineralizing

solution cell. This research was performed in collaboration with scientists from the Health Foundation Research Unit (American Dental Association) at NBS.

[1] S. Takagi, L. C. Chow, W. E. Brown, R. C. Dobbyn, M. Kuriyama,

Nucl. Instr. Meth. in Physics Res. 222: 256-258 (1984).

[2] S. Takagi, L. C. Chow, W. E. Brown, R. C. Dobbyn, M. Kuriyama, J.

Dental Res. 64: 866-869 (1985).

X-Ray Topographic Examination of LiNbO^ Single Crystals

Subtask 3

G. G. Long and M. Kuriyama

Single crystal lithium niobate (LiNbC^) is currently the nonphoto-refractive, electrooptic material of choice for optical switching and modulation

technology. The prominance of lithium niobate technology has very recently been enhanced by the announcement of laser action in doped samples. In

this work, which was performed in collaboration with a scientist from the

Ceramics Division, only measurements of undoped material was involved.

High sensitivity monochromatic (8 keV) x-ray topography was carried out on two z-cut (0001) crystals from z-grown boules, two y-cut (0110) crystals

from y-grown boules and one z-cut crystal from a boule grown in the ydirection. The major type of defect observed was a filamentary structure

which appeared with different density in various crystal samples. For

example, the density of filaments was quite different for the two z-cut

15
samples, where the defect-free volume was much greater in the (optically) good sample. Data from the y-cut crystals showed that the defectfree volume may be even greater than that in the better z-cut crystal. In

addition to the filamentary defects mentioned above, there was also

evidence of periodic striations in topographs from some of the crystals.

Energy Dependent X-Ray Topography of Bi ^SiOon Single Crystals

Subtask 4

G. G. Long and M. Kuriyama

Single crystals of bismuth silicate (Bij^SiC^o) are of primary importance

in spatial light modulator technology. The property of greatest interest

is its photorefraction. Much effort has been devoted to the growth of

good crystals, but it has thus far been difficult to obtain detailed information on crystal quality. In this work, performed in collaboration

with a scientist from the Ceramics Division, high sensitivity monochromatic topography was used to examine the nature of both bulk and surface

crystal structure, and to observe defects not detectable by traditional

optical inspection. Three samples were studied, all from the same boule

grown in the < 001 ^ direction. Under a polarizing microscope, they each

appeared to be nearly free of birefringent strain. Two important

properties of the samples were apparent: there are significant surface

imperfections, and there is a segmented appearance to the diffracted

image. Crystal growth bands are evident in the four outer segments, and

fringes are seen in the central segment. Since the (100) and (110)

crystal faces grow at different rates, this introduces characteristic

stresses. Sharp boundary lines are clearly visible between each of the

segments. Each crystal topograph contains information on a slice in the

thermal history of the growth of the crystal. The nature of the fringes

in the central region were studied using reflection topography at ten

different x-ray energies. No change in the moire was seen even in the

neighborhood of the BiLjjj edge. Real time depth profiling of these

crystals was carried out based on References 1 and 2.

[1] M. Kuriyama and G. G. Cohen, Z. F. Naturf. 37a , 465 (1982).

[2] M. Kuriyama and G. G. Long, in Applications of X-Ray Topographic

Methods to Materials Science, ed. by S. Weissmann, Plenum, NY 97-

109 (1984).

Perfection of Copper Single Crystals

Subtask 5

D. R. Black, G. G. Long, and M. Kuriyama

In the study of interfaces in metals and alloys, the crystal perfection of

substrate materials often affects the structure and microstructure of

films deposited on the substrates and these effects obscure the nature of

interfaces. It is a serious problem to find a way to hold ductile

substrate crystals without introducing deformation during cleaning of the

substrate surface and deposition of films in a vacuum chamber. Disks of

copper, 0.5 mm to 1 mm thick, were prepared from a boule grown by the

Czochralski method [1, 2]. They were annealed in a hydrogen furnace at

16
1000° C for a week. A diffusion zone approximately 15 micrometers thick

was created between the oxygen free copper mounting plate and the single

crystal. The monochromator system at X23-A was operated to create a large

(2 cm X 2.5 cm) parallel beam. Topographs were taken with the beam

operated at 7 , 8 and 9 keV, using (111) asymmetric diffraction in transmission. Anomalous transmission was evident, where the same quality of

crystal perfection was in evidence as before the diffusion bonding. This

experiment confirms that diffusion bonding may be used for metal crystal

mounting without causing deterioration in crystal quality.

[1] M. Kuriyama, J. Early, H. Burdette, J. Appl. Cryst. 7_ 535 (1974).

[2] W. Boettinger, H. Burdette, M. Kuriyama, Phil. Mag. 34 119 (1976).

X-Ray Raman EXAFS of Low Z Elements Using Hard Radiation

Subtask 6

D. R. Black, G. G. Long and M. Kuriyama

Using a double crystal x-ray spectrometer, K-x-ray Raman edges in the

inelastically scattered spectrum of 8 keV radiation from lithium,

boron, carbon and nitrogen have been observed. Recent experiments have

concentrated on boron nitride and polycrystalline graphite as standard

samples with known structure. Good resolution carbon spectra, showing the

characteristic pre-edge peaks and fine structure, were obtained. The fine

structure above the edge can be analyzed in a fashion similar to that of

EXAFS data to extract near neighbor atomic distances. The initial step in

the Raman data analysis was a deconvolution of the data to remove the

instrument profile. The standard method for performing this deconvolution

is difficult to apply to this data. To solve this problem other

deconvolution techniques have been investigated. In particular, the Root

Projection Deconvolution algorithm developed at NBS for the analysis of

acoustic emission waveforms has been applied. Preliminary results are very encouraging. The problems of amplified high frequency noise and

truncation errors are substantially reduced. A first application to data

from boron nitride indicate that the deconvolved data is suitable for

further analysis.

Local Atomic Environments in Icosahedral Aluminum-Manganese Alloys

Subtask 7

M. Kuriyama, G. G. Long, and R. D. Spal

As part of this subtask, the topological properties of the atomic scale

structure description of the icosahedral phase developed earlier [1, 2, 3]

were investigated. In a periodic crystal, the local environment of an atom is described most easily by its point symmetry within the space group

to which the structure of the crystal belongs. The Wigner-Seitz (W-S)

cells about the atom give additional information in this case. For icosahedral crystals, for which there is as yet no appropriate crystallographic description, the W-S cell may be the only way to study the local

environment. Applying the W-S constructs, it was found that: i) there is

a broad distribution of Mn site W-S cell topologies and an even broader

one of A1 site topologies. The volumes span those appropriate to Mn and

17
A1 and they tend to fall into two well-defined groups withA/20% characteristic of Mn; ii) No sites were found to be or (0,0,12,Vg), Vg = 0, 2,

3 or 4. Cells with these topologies are the building blocks of the Frank

Kasper structures. iii) The radial distribution function (RDF) shows

nearest neighbors lying between 0.25 and 0.3 run in a bimodal distribution, and narrow peaks were observed beyond 0.6 nm, implying long range

positional correlations characteristic of a crystal and inconsistent with

a glass. iv) The coordination number is between 12 and 12.5 for Mn,

compared to 10 in crystalline MnAlg.

In the other part of this subtask [4], an infinite class of quasiperiodic

lattices, whose diffraction patterns have icosahedral symmetry, was derived. This class of lattices is composed of incommensurately modulated

sublattices with displacive modulations. The sublattice reference lattices, as well as the sublattice displacement fields, belong to the space

group R3m, and are equivalent under the icosahedral point group. The relative positions of the reference lattices and displacement fields are described by a three dimensional vector a

2

* As a2 varies continuously, the

quasilattice changes discontinuously , but its diffraction pattern remains

the same. The amplitude of the displacement field is described by a function u belonging to an infinite class of periodic, discontinuous functions. As u varies continuously, the quasilattice and its diffraction

pattern change continuously. For general u, the quasilattice has

infinitely many nearest neighbor configurations, unlike icosahedral

quasilattices constructed by the projection and grid methods. A special u reproduces a three dimensional generalization of the Penrose tiling.

[1] M. Kuriyama, G.G. Long, L. Bendersky, Phy. Rev. Lett. 5j3, 849

(1985).

[2] G. G. Long, M. Kuriyama, Acta Cryst. A42 , 156 (1986).

[3] M. Kuriyama, G. G. Long, Acta Cryst. A42 , 164 (1986).

[4] R. D. Spal, Phys. Rev. Lett. 56, 1823 (1986).

Construction of an X-Ray Camera Using a CCD Sensor

Subtask 8

R. D. Spal and M. Kuriyama

An X-ray camera based on a CCD sensor is under construction. It promises

to deliver better sensitivity and/or resolution than current x-ray cam- eras. Four printed circuit boards were designed for the camera. The CCD

mounts on the first board, which also serves mechanically as one wall of a thermoelectrically cooled, vacuum sealed enclosure. This board also con- tains a buffer amplifier for the CCD output. The second board has the

high speed drivers for the three parallel and serial CCD gates. The third

board contains the analog circuits to convert the buffered, clocked CCD

output into an RS170 video signal. The fourth board has the digital circuits to control the second and third boards. Due to the high frequency

(7MHz), high slew rate (3000V^.sec) , and high peak current (1 amp) required to drive the CCD gates, it is anticipated that the current design will

undergo several revisions before a satisfactory printed circuit board layout is found. Computer aided design software has been developed to facilitate the process of revising and producing the boards.

18
METALLURGICAL PROCESSING John R. Manning

The objective of this task is to develop measurements and processing models

to allow prediction and control of the effect that processing history has

on alloys. Alloy properties depend on the microstructures and composition

distributions that are developed in the alloy during its solidification and

subsequent solid state processing. Proper control of processing conditions

allows tailoring of alloys to produce microstructures, compositions and

properties needed for particular applications. The NBS work develops

overall predictive guidelines relating these conditions to final alloy

results. These guidelines then can be applied by industrial alloy

designers to their particular problems, thus providing increased

reliability, cost savings and higher performance in final products.

The NBS effort emphasizes three major areas of work: (1) rapid

solidification, which allows production of advanced alloys unobtainable by

conventional means, (2) improved understanding and control of conventional

solidification processes to produce economical high quality materials, and

(3) kinetic processes in solids, especially those connected with reactions

at interfaces, which significantly alter alloy microstructures, composition

distributions, and properties even after solidification has occurred.

As an unexpected result of the investigations of rapidly solidified alloys

which provide extended solid solubility, a dramatically new class of

materials, called quasicrystals, was recently discovered at NBS when very

high levels of Mn were added to Al. In addition, as part of the NBS study

of solid state processes and alloy interfaces, mechanisms for another

unexpected phenomenon, diffusion-induced grain boundary migration, have

been determined. These results, while important in themselves, also had

wider implications, such as indicating the large effect that coherency

strains can have on many interface processes, including those in metal

matrix composites. The quasicrystal discoveries even have changed our basic ways of thinking about possible crystal structures and how they are

formed. This work is now being pursued further to investigate additional

practical and scientific consequences. In an application of previous work

on controlled solidification having similar broad implications,

calculations of interface instability and associated segregation effects

have been extended to the higher solidification velocities typical of

continuous casting of thin steel sheet. This extension was done as part of

the new Congressionally-mandated NBS steel research program.

In addition to working with the steel industry on problems concerning

continuous casting, staff members have interacted with many other industrial groups, for example, collaborating with industrial scientists in

producing special rapidly solidified alloys. Much of the current work also

is supported by other government agencies. Interface studies for application to metal matrix composites and studies of stress effects on alloy

coarsening are being funded by the Office of Naval Research. Studies of

coarsening in liquid-solid mixtures and of convection and interface stability during directional solidification are being sponsored by the National

Aeronautics and Space Administration. Powder processing of rapidly

solidified Al-Fe alloys is supported by the Naval Air Development Center.

Major studies on quasicrystals and rapid solidification were funded during

the past year by the Defense Advanced Research Projects Agency.

19
FY 86 Significant Accomplishments

o Mechanisms were determined by which fine dispersoids can be produced in

rapidly solidified Al-Ni-Fe alloys, which are of industrial interest

because of their intermediate high temperature strength. High

solidification rates in these alloys produce discrete beads of liquid

rich in Fe and Ni within an A1 alloy matrix. Subsequent freezing of

these beads produces uniformly distributed intermetallic phase

dispersoids, which provide the desired hardening and alloy strength.

o Experiments on nucleation of quasicrystals in submicron atomized

droplets showed nucleation rates so high that microquasicrystalline

structures almost indistinguishable from those of a metallic glass were

formed.

o The special nucleation and growth behaviors of quasicrystal alloys were

analyzed. These studies not only yielded information on processing

paths for production of these extraordinary 5-fold and 10-fold symmetry

alloys but also provided general insights into the growth of complex

crystal phases and the structure of supercooled liquids from which

quasicrystals can be formed.

o For iron-carbon-sulfur ternary alloys, limiting conditions of

solidification velocity, temperature gradient, and alloy composition

were calculated for the onset of cellular growth. In addition, cell

spacings, which provide the scale of expected alloy segregation in these

steel materials, were determined for this onset condition in the high

velocity ranges typical of thin sheet continuous casting of steel.

o Electron microscopy results on microstructures formed near interfaces in

single phase Cu- CuZn systems showed that surprisingly high dislocation

densities were generated by diffusion across these interfaces. This

implies that large elastic energies are being developed in the

interfacial region. Significant changes in equilibrium compositions

near these interfaces are calculated to result from these effects.

Rapid Solidification

Subtask 1

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

F. S. Biancaniello, and J. W. Cahn

Rapid solidification and subsequent thermomechanical consolidation permits

a new approach to alloy design. Application of predictive modelling and

microstructural control to these processes can permit the tailoring of

microstructure to meet specific alloy property requirements. To promote

the development of this new design strategy into a mature element of the

field of metallurgy, research has been performed in three areas: (a) an exploration of new metallic metastable phases with unique structure and

properties, with emphasis during the past year on quasicrystal alloys; (b)

mechanisms of microstructure formation; and (c) improvements in processing

techniques used for the production of rapidly solidified alloy particulate.

20
Quasicrystal Phases

Quasicrystalline intermetallic phases, which were initially discovered

during rapid solidification studies at the National Bureau of Standards,

have symmetries which are not allowed by classical crystallography. Since

the initial announcement of the NBS discovery of quasicrystalline Al-Mn in

November 1984, these materials have attracted intensive study in many

laboratories. Rapid progress has been made at NBS in understanding both

the crystallography and the kinetics of formation of these materials.

The symmetries of the quasicrystalline phases are icosahedral, with six 5-

fold axes, or decagonal, with one 10-fold axis. The lattices of crystals

with these symmetries must be quasiperiodic in three dimensions, but they

can be described as periodic lattices of higher dimension which are projected into three dimensions. Such a formulation is being used for the

analysis of x-ray, electron, and neutron diffraction data and has had

considerable success in describing the positions and intensities of the

diffraction peaks. Understanding of the atomic configuration which can decorate such lattices is being gained through the analysis of data from

EXAFS, NMR, Mossbauer spectroscopy and other techniques. In several cases,

these experiments have been carried out at other laboratories using samples

provided by NBS. In addition, NBS guest scientists D. Shechtman and L.

Bendersky from the Technion and Johns Hopkins University, who originally

identified these materials, are continuing to work at NBS on these

problems. These studies have led to the conclusion that many quasicrystals

contain local atomic groups which are the same as those in crystals of

similar compositions, but these groups are packed together differently.

In addition to their unique crystallography, quasicrystals have unusual

nucleation and growth behavior which is providing insight into more general

studies of the structure of supercooled liquids and the growth of complex

crystal phases. In Al-Mn quasicrystalline alloys it is found that the

quasicrystals replace the equilibrium phases because of their much higher

nucleation rate in the supercooled liquid. For alloys atomized into

submicron droplets, it was found that in the smallest drops, which would

have had the highest cooling rates, the nucleation rate was so high that it

produced a microquasicrystalline structure, almost indistinguishable from

that of a metallic glass (fig. 1). Such high rates of nucleation give

support to current theories of icosahedral clustering in supercooled

liquids. Electron beam surface melting experiments also demonstrated that

the icosahedral phase of Al-Mn serves as a potent nucleation substrate for

the somewhat more stable decagonal phase, with the result that the

decagonal phase replaces the icosahedral phase unless the cooling rate

following the initial solidification is sufficiently high.

Mechanisms of Microstructure Formation

Systematic research has been continued to discover the mechanisms and thus

the conditions which produce the wide variety of microstructures possible

in rapidly solidified materials. For example, experiments on Al-Fe-Ni

alloys were focused on the formation of small ~30 nm diameter particles of

intermetallic phases (dispersoids ) within a matrix phase.

21
Rapidly solidified alloys containing fine dispersions of intermetallic

phases constitute a technologically important class of materials. After

consolidation into bulk samples these materials can exhibit unique

mechanical properties and elevated temperature capability. Dispersoids

form by two mechanisms in these samples: directly from the melt and by

precipitation from the solid state. In the Al-Fe-Ni system precipitates

formed in the solid state have a disk morphology and are therefore

distinguishable from those formed by solidification. Using the electron

beam melting and resolidification technique, the microstructures obtained

by rapid solidification at controlled rates between 0.25 and 500 cm/ s were

obtained in Al-3.7 wt% Ni-1.5 wt% Fe, an alloy currently being considered

by Alcoa as a material with intermediate high temperature strength. This

hypereutectic alloy, which in its cast form exhibits coarse primary

intermetallics of Alg(Fe,Ni), solidifies as a fine coupled eutectic for

solidification velocities below ~2. 5 cm/s. Above this rate a cellular

structure of a-Al forms with continuous sheets of the intermetallic phase

coating the cell walls. The eutectic and cell spacings are shown in figure

2. These sheets likely form by solidification of the Fe- and Ni-rich

intercellular liquid as shown in the left of figure 3. At higher

solidification rate these deep intercellular liquid regions become unstable

and discrete "beads" of liquid, which subsequently freeze as Alg(Fe,Ni),

are left by the cellular interface, as shown in the right of figure 3.

This process which provides a desirably uniform distribution of dispersoids

occurs for solidification rates above ~1 00 cm/s.

Powder Processing

Inert gas atomization is an important method for the production of rapidly

solidified alloy powders. A full scale atomizer is nearing completion and

fundamental studies into the mechanism of powder formation and process

control have been initiated. A detailed flow study of high energy helium

jets was performed to determine the optimum geometry of the exit nozzle

used to deliver molten metal to the higher energy jets. An additional high

pressure-high flow system was built that duplicates the flow capability of

the atomizer and allows us to take high speed photographs of the

atomization of water under varying flow conditions. In addition,

aspiration tests were run to determine optimum helium jet velocity. This

study showed that optimum particle disruption occurs at a jet delivery

pressure of 11.7 mPa (1700 psi) for helium gas. These flow conditions were

then duplicated in a small (1 Kg) batch atomization of Sn-95 wt% Sb, with

much of the powder produced being in the 10 /am to 50 /j.m diameter range.

Commercial alloy powders in this size range provide improved product

properties after consolidation. Studies to determine the optimum

conditions for consolidation of commercial Al-8 wt% Fe rapidly solidified

powder with minimum microstructural coarsening have been conducted.

In the area of electrohydrodynamic (EHD) atomization, which produces small

amounts of very fine powder (<1 jum), system modifications included a change

to a wire feed-electron beam melting source and new vacuum plumbing. This

combination increased the upper temperature limit for alloys which can be

processed into the 4000°C range as well as providing better process

control

.

22
Controlled Solidification

Subtask 2

S. R. Coriell, R. L. Parker, 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.

Numerical calculations in collaboration with G. B. McFadden, R. F.

Boisvert, and R. G. Rehm of the NBS Center for Applied Mathematics and R.

F. Sekerka of Carnegie-Mellon University have modelled double-diffusive

convection and interface stability during alloy solidification. Algorithms

have been developed to calculate both two- and three-dimensional cell

shapes that occur during directional solidification. These 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 continuous casting of steel. Ultrasonic techniques have

been developed to measure interface position, velocity, and morphology

during solidification of metals and semiconductors, including aerospace

alloys. This work, undertaken in collaboration with N. C. Peterson of the

Polytechnic University of New York, is directed toward the monitoring of

casting, solidification, and crystal growth processes to provide real-time

feedback and control, thus aiding in providing a uniform product and

increasing productivity.

Convection and Interface Morphology during Directional Solidification

Solute segregation in directionally solidified materials is caused by fluid

flow in the melt and by nonplanar interface morphologies. One of the goals

of this work is to determine the role of buoyancy- driven fluid flow on solute segregation during directional solidification. Avoidance or minimization of segregation can be extremely important in high performance

materials. In this work, directional solidification vertically upwards at

velocity, V, was considered for a binary alloy which upon freezing rejects

a solute which is lighter than the solvent, for example, lead containing

small amounts of tin. Numerical results were obtained using finite

differences in a two-dimensional time-dependent model that assumes a planar

crystal-melt interface. Calculations were carried out for Schmidt numbers

(ratio of kinematic viscosity and solute diffusivity, D) of 81 (typical of

metals), 10 (typical of semiconductors) and unity. A detailed study of

flow transitions for Schmidt number of unity shows that multiple steadystates, time-periodic states, and quasi-periodic states occur as the solute

concentration increases. The multiple steady-states indicate that the flow

field and the resulting solute segregation depend on initial conditions,

and hence on how the final processing conditions are attained. Steady

flows cause lateral solute segregation, while time-periodic flows cause

both lateral and longitudinal segregation. The period of the time periodic

flows is roughly given by the time for the crystal to grow a distance D/V.

Thin sheet continuous casting of steel alloys produces solidification

conditions that differ significantly from those encountered during

conventional ingot casting. Notably, the rates at which the solid-liquid

23
interface advances during these continuous casting processes are much

faster than those in conventional processes. During solidification, the

shape of the solid-liquid interface may vary from smooth to cellular to

dendritic. The processing conditions for the transition between planar and

non-planar solidification for particular steel alloys and the

characteristic wavelength of the microsegregation are being determined by

linear morphological stability theory, which is being extended to

multicomponent systems. The processing conditions (solidification

velocity, temperature gradient in the liquid, and alloy composition) for

the onset of cellular growth and the cell spacings at the onset have been

calculated for the iron-carbon-sulfur ternary system with the assumption of

constant liquidus slopes and constant distribution coefficients. In

general, the distribution coefficient (ratio of solute concentration in the

melt and in the solid at the solid-liquid interface) will depend on the

concentration of all the other solutes in the alloy, and there may be

coupling in the diffusion processes at the interface. The linear

morphological stability theory will be extended to these more complex

cases

.

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 technique has application to process control in any casting,

crystal growth or solidification process whether fast or slow, high or low

alloy, metal or semiconductor. This real-time ultrasonic metallography

will be important to any materials 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.

Examples of such industries are steel, non-ferrous metals, and the

electronics industry involving silicon crystal growth; all of which are multi-billion dollar industries in the U.S.

In addition to recently published NBS measurements on iron and steel, which

showed quantitative pulse-echo observations of the melting and freezing of

pure iron and 304-stainless steel, measurements also have been made of

solidification in silicon. As in the steel measurements, combined

induction and arc heating was used to obtain unidirectional heat flow.

These new results on silicon, which show that silicon crystal growth can be

monitored in real-time in situ with the pulse-echo technique, have elicited

widespread interest in the crystal growth industry.

Digital signal processing techniques for this work have been improved to

handle currently 100,000 pieces of data per second in the signal averaging

mode. This capability is important to allow rapid, accurate determination

of interface positions and eliminate spurious signals. Application of this

technique to gallium arsenide crystal growth appears promising, as well as application for monitoring the processing of directionally solidified

turbine blades (high nickel alloys) for aerospace applications. Work has

started on developing the technique to provide in-situ real-time monitoring

of rapid solidification processing.

24
Solid State Processes and Alloy Interfaces

Subtask 3

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

S. A. Hackney, and C. Rottman

Reactions at interfaces are important in a number of practical materials,

including metal matrix composites, surface modified alloys, and alloys

undergoing coarsening. Stresses produced near interfaces by diffusion

reactions and lattice mismatches can strongly affect alloy properties.

Determining how such stresses influence the alloy compositions, gradients,

and reaction rates near these interfaces is an important aspect of the

current work. In addition, volume fraction effects on alloy coarsening are being investigated in solid-liquid alloy systems where these stresses are absent. Of particular interest have been coherency strain effects which

not only play an important role in diffusion- induced boundary migration

effects but also are predicted to significantly affect compositions near

interfaces in general, including those in composite materials.

Thermodynamics and Kinetics of Reactions at Non-Equilibrium Interfaces

Coherency strains and stresses are generated during interdiffusion at the

interface in a binary solid solution diffusion couple when the lattice

parameter is a function of composition. 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 inclusion of this stress discontinuity

into the thermodynamic equations leads to a prediction that a chemical

discontinuity also will exist at the interface. Calculations have been

performed to assess the magnitude of this compositional discontinuity,

starting with alloys of the same phase but of different initial

compositions. Significant concentration steps, greater than 0.2 mole

fraction, are predicted, as shown in figure 4 for Cu-Ni. Measurements of

diffusion profiles perpendicular to grain boundaries and interfaces are being performed and the structure of the diffusion zone affected by these

stresses is being assessed by TEM and field-ion microscopy. Temperature

effects and misorientation effects on grain boundary structure also have

been calculated.

Electron microscopy observations and thermodynamic calculations have been

made of interfaces between Cu and a-phase Cu-Zn. The observed <110>

dislocation patterns that develop during diffusion of Zn into the Cu side

of the interface show surprisingly high dislocation densities, confirming

that appreciable lattice stresses are being produced. Initial indications

are that the defect density is even higher than would be expected from

lattice parameter gradients alone. The additional defects perhaps are created by the net vacancy divergence which arises because Zn diffuses

across the interface faster than does Cu (Kirkendall effect). The

resulting gradient in lattice sites produces plastic distortion and a significant extra work term. The effect of these extra terms on the

analysis of multicomponent diffusion could be significant since stress

effects from these sources have not usually been included in the

thermodynamic equations.

25
Diffusion-Induced Grain Boundary Migration

Grain boundaries in polycrystals, when exposed to a solute source, have

been found unexpectedly to migrate and to form solid solutions in the

regions swept by boundary motion. Examination of this diffusion-induced

grain boundary migration (DIGM) in the Cu-Zn system by transmission

electron microscopy (TEH) has revealed the following general physical

features: (a) a dislocation "wall" is formed at the original position of

the grain boundary, (b) the region over which the grain boundary has

migrated is alloyed with Zn, (c) the grain boundary has a high density of

defects having step character which show contrast behavior expected of

extrinsic grain boundary dislocations produced by stress, and (d) the

region in front of the migrating grain boundary is plastically deformed.

Because of the large amounts of energy required to produce these

dislocation arrays, none of the currently proposed mechanisms for DIGM can explain all of these recent electron microscopy results. However, the

dislocation observations clearly indicate that stress effects are important

at the moving interface and that stress relief occurs at the original grain

boundary position. A possible mechanism map for DIGM has been derived

which contains various diffusion and migration regimes where different

driving forces can dominate. The features of this map are qualitatively

consistent with the microstructural results obtained on the Cu-Zn system.

Alloy Coarsening

Often commercial alloys obtain improved properties through the presence of

coherent precipitates which engender long range stress fields. These,

elastic fields can have a profound effect on phase equilibria and phase

transformation kinetics. In current work done in collaboration with W. C.

Johnson of Carnegie-Mellon University, it has been shown that in such alloy

systems these stresses produce a processing path dependence of the

equilibrium phase diagram, so that the phase diagram is not a unique

function of alloy composition, temperature, pressure and materials

constants. An important result from the study of precipitate coarsening is

that inverse coarsening, where small particles grow at the expense of large

particles, instead of the usual case where the small particles shrink, can

be obtained. Specific predictions are being generated concerning the

kinetics and conditions for inverse coarsening. These results could be

very important in aiding the development of stable precipitatestrengthened alloys.

Experiments have been conducted using small Sn crystals in Sn-Pb eutectic

liquid to provide the first experimental test of coarsening theory in a system in which all the materials parameters necessary for comparison to

theory are known a priori. Detailed numerical calculations which account

for the free-boundary nature of the coarsening problem have been performed

to understand the morphology of the solid particles observed in these

experiments involving high volume fraction of solid. The calculations are consistent with the experimental results.

26
Fiq. 1. Size of coherently reflecting zones plotted against particle

The corresponding electron diffraction patterns consist of (A) spot y

(B) continuous rings, and (C) broad glass-like rings..

diameter,

rings

Fig. 2. The effect of solidification velocity on microstructure and the spacing

of eutectic and cellular structures in Al-Fe-Ni alloys.

27
A MECHANISM FOR DISPERSOID

FORMATION BY RAPID SOLIDIFICATION

Fig. 3. Schematic representation of different ways the intermetallic phase forms at

cell walls. At intermediate solidification rates, continuous sheets of AlgFeNi form

on the cell walls. At high solidification rates, liquid pockets are formed at the

liquid-solid interface and subsequently solidify to form the discrete particles of

Fig. 4. Effect of elastic strain energy on alloy compositions near interface in

single-phase Cu-Ni alloy system. When diffusion occurs across the interface, the

resulting gradients in composition and lattice parameter introduce elastic energy

proportional to the square of the strain. The predicted equilibrium compositions

on each side of the interface are the compositions Ccu and tf^-j where the corrmon tangent to the free energy curves for the two stressed materials touches these curves.

28
WEAR AND MECHANICAL PROPERTIES A. W. Ruff

Research is carried out to improve measurement methods and to develop

standards related to wear and mechanical properties of metals. A

significant portion of the effort is directed towards an improved

understanding of the physical mechanisms involved in wear, friction, and

mechanical behavior. The methods used include wear and mechanical

testing, optical and electron microscopy, microindentation measurements,

metallography, surface analysis, and wear particle analysis. An

additional activity in the task includes corrosion and fatigue behavior of

alloys used in synthetic implants.

Wear and mechanical performance of industrial systems of all levels of

complexity, including also a wide range of consumer products, is an important part of the nation's industrial effort. Costs associated with

failure and inadequate performance in these areas have a significant

economic effect. Greater use of stronger, more wear-resistant materials

can improve productivity and our competitive position world-wide. This

task is developing test methods suitable for evaluating new materials

having improved mechanical and wear properties. This work leads to data

on such materials that may be used by design engineers in applying new

materials to use. One example of a currently important area is that of

metallic coatings. There are no adequate standard methods for measuring

the wear performance of coatings. In their absence, users have no basis

for making choices among available coatings for better wear performance.

One new area of emphasis in this task is that of wear data for

commercially important alloys and coatings.

The work of the Group is supported in part by a number of other Federal

agencies in recognition of the importance of adequate wear and mechanical

behavior of machinery and mechanical systems. The Department of

Transportation (DOT) supports our work in failure prevention for small

pressurized containers that may contain toxic materials, or in the

opposite extreme, breathing air for rescue personnel. In any case sudden

fracture or slow leak failure can create unacceptable consequences. Our

research on test methods and failure mechanisms has led to new U.S.

regulations in this area. 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,

and a new model for alloying effects on galling wear has been developed at

NBS. The Office of Naval Research (ONR) supports a beginning effort to

measure the dynamic mechanical properties of energetic (explosive)

materials. A unique micromechanical testing approach developed in our laboratory has provided the first set of dynamic strength and fracture

data on such materials in pure, crystalline form. The data will enable

evaluation of a dislocation-based theory of "hot spot" formation preceding

ignition of those substances.

Numerous activities in the Group also have significant involvement with

private industry. We are funded by C. S. Draper Laboratory, Inc., Boston,

MA, to conduct state-of-the-art creep measurements on highly stable

materials used in gyroscope systems. We are conducting joint measurements

with Deere and Company, Moline, IL, on galling wear properties of

29
materials that may have future application in critical machine service.

We have begun measurements jointly with Minnesota Mining and Manufacturing

Company, Minneapolis, MN, on the micromechanical properties of magnetic

recording discs. We are working with several implant manufacturing firms,

including Howmedica, Inc., NJ, and DePuy Manufacturing Company, Inc., IN,

to evaluate new materials for future prosthetic devices. In all of these

cooperative activities, our measurement and metallurgical expertise is

contributed to enable a more accurate understanding of material behavior

in wear and mechanical properties. In addition, we contribute to the

improved understanding of the fundamental mechanisms that are involved.

FY 86 Significant Accomplishments

o An analytical model has been developed for friction and wear break-in

of sliding metals. The model also considers longer term transitions

(sudden changes) that reflect change in the wear or friction

mechanisms at work. Experimental work has produced data that is

being used for testing and improving the model.

o Dynamic deformation and fracture properties have been obtained from

small crystals of an energetic material, cyclotrimethylene

trinitramine (RDX), using instrumented microindentation. The results

are a first indication of a loading rate dependence of onset of

fracture in such materials. The behavior is being analyzed in terms

of a dislocation-based model of hot spot formation.

o A workshop on tribology data and information was planned and held at

NBS with leadership from this task. Approximately AO individuals

from both universities and private organizations participated over a four week period. Several foreign tribologists also participated. A

report containing specific recommendations has been prepared, and

some of the efforts are now underway. Funding for the work will come from DOE, other federal agencies, and the private sector.

o Studies of wear of chromium plating used in a currency printing

process have led to the identification of the principal wear and

corrosion process, and to the development of two laboratory wear

tests that can be used to evaluate new plating methods and the inks

involved in the process. The results and test methods will be

utilized by the U.S. Bureau of Engraving and Printing.

Wear of Materials

Subtask 1

P. J. Blau, L. K. Ives, A. W. Ruff, M. Peterson, J. Harris, P. Boyer, and

E. Whitenton

Friction and Wear Break-in

The previous year witnessed the development of an analytical framework for

a model for the frictional running-in behavior of sliding metals. The

model was based on an extensive survey of tribology literature and

in-house experimental work performed on a series of ferrous and

30
non-ferrous alloys over the last five years. The current year's research

has extended the model to consider the case of longer term frictional

transitions whose occurrence usually coincides with changes in the

dominant modes of wear in the sliding contact zone. These transitions are frequently associated with such processes as nucleation and growth of

sub-surface fatigue cracks, the formation of oxide films during sliding,

debris compaction and accumulation, and the deposition of micrometer- thick

lamellae of displaced and highly deformed material. Longer duration

experiments complemented the development of transition terms for the

model. These experiments were conducted on a reciprocating ball-on-flat

tribometer to study the behavior of a tarnished Cu-5 wt%Sn alloy and a specially heat-treated Cu-15 wt%Ag alloy (fig. 1). The microstructure of

the Cu-Ag alloy was tailored to provide large Cu grains surrounded by a thin, continuous network of Ag-rich constituent (eutectic). It was used

in this condition to provide "built-in" microstructural markers for

tracing the high near-surface strains associated with frictional shear

damage. Characteristic running-in behavior of the Cu-Ag alloy is shown in

figure. 1. Plans for FY 87 are to test the validity of the model with

further experiments and to incorporate functional relationships between

test load and the incubation period preceding sudden friction transitions.

Wear Properties of Metal Coatings

Studies are being carried out on a series of Ni-Cu composition modulated

layered coatings on steel that were prepared by the Electrodeposition

Group. Sliding wear experiments have been conducted under dry conditions

in air using the new crossed cylinder tester that has recently been

standardized by the ASTM committee G-2. A slow sliding speed of 1 cm/

was selected to avoid surface heating. Both the load dependence and

sliding distance dependence of wear rate were measured for three different

coatings, and for the two base metals, Ni and Cu. The counterface was

52100 bearing steel. The smallest layer spacing of 10 nm showed a much

reduced wear rate over the coatings with spacings of 100 nm and 300 nm, so long as the contact stress during wear was sufficiently low. For higher

stresses the wear rate increased to that of the other coatings. These

results appear to be consistent with the model of dislocation barriers at

each internal interface between layers which offer resistance to the

growth of plastic deformation beneath the wearing contact. This

subsurface plastic deformation is the principal mechanism in the failure

process that produces wear debris under the test conditions being used.

Plans for next year include microscopic studies of the deformation

associated with the wear zone so that direct evidence can be obtained for

the barrier effect at the layer interfaces.

Galling Wear

A comprehensive investigation of the process and mechanism of galling of

metals is being conducted partly under the sponsorship of DOE. Galling is

a severe form of wear which occurs at sliding surfaces, leaving them

markedly roughened as a result of plastic deformation, fracture, and

transfer of metal from one surface to the other. The DOE has identified

galling as a significant cause of failure of valves which are employed to

control the flow of gasses and fluids in energy conversion systems.

Roughening of the valve sealing faces by galling results in an increased

31
rate of leakage. Galling may also lead to complete seizure of the valve.

An important part of our program has been the study of the influence of

various metallurgical parameters on galling severity. Twelve pure metals,

six binary alloys, and numerous complex multiphase alloys have been

studied. Among the pure metals it has been found that strength related

properties such as hardness have little effect on galling severity. On

the other hand, the mode of deformation has a strong influence. Hexagonal

close packed metals that deform predominantly by basal slip have a much

greater resistance to galling than body centered cubic and face centered

cubic metals. Similarly, in the study of Cu-Al and Cu-Ge binary alloys,

stacking fault energy which influences the mode of deformation was also

found to affect galling severity. The galling behavior of several

commercial steels having different heat treatments and surface treatments

such as carburization has been of special interest. Figure 2 shows some results that were obtained for sliding couples of quench hardened

AISI 1541 steel and case carburized AISI 8620 steel. Detailed studies by

means of scanning electron microscopy of the initiation and subsequent

propagation of damage have indicated that the mechanism of galling is what

has been referred to as "prow" formation. An Industrial Research

Associate from Deere and Company works with us on this project.

Wear of U.S. Currency Printing Plates

Wear of currency printing plates is a serious problem affecting both the

quality of the impression and the unit cost. The objectives of this

project which is sponsored by the Bureau of Engraving and Printing are:

1) determine the mechanisms responsible for the wear of printing plates,

2) develop a laboratory wear test for the evaluation of materials employed

in the printing process, and 3) carry out laboratory wear tests to

evaluate the wear performance of experimental electroplatings. The

project is being conducted jointly with members of the Electrodeposition

Group. Currency printing plates consist of a relatively soft

electroformed sheet of nickel onto which a layer of hard chromium is

electrodeposited. The wear life of the chrome plating depends on the

properties of the plating itself, the ink employed, and the printing press

operating parameters. Two laboratory wear tests have been developed to

investigate the wear process. Based on results obtained with these tests

and on the examination of actual worn plates it appears that the abrasive

wear probably consists of direct loss from the chrome electroplate as well

as loss by removal of the oxide film that forms on the surface of the

chrome as a result of chemical reaction with the atmosphere and the ink.

Our studies have indicated that increased wear life can be obtained with

improved chrome plating materials. However, results have also shown that

ink rheology and particle content coupled with the operating conditions of

speed and load have a strong influence on wear rate.

ASTM G-2 Committee on Wear and Erosion

Several staff members continue to participate in the wear standardization

work of this committee. Chairmanship is held of the Operations

subcommittee, the Terminology subcommittee, and of the task group on solid

particle jet erosion testing. Major contributions are also made in the

task groups on galling wear, on crossed cylinder wear testing, and on friction measurements. We are also participating in the planning of

32
several future symposia and workshops. There are about 80 members of the

Committee from private industry, so there is ample opportunity for our staff to interact in an effective manner.

Mechanical Properties

Subtask 2

R. S. Polvani, J. H. Smith, P. Boyer, and E. Whitenton

Dynamic Microindentation

Industrial designers need data for dynamic mechanical properties of

materials. A new and nondestructive approach to dynamical mechanical

testing has been developed in this project. Derived from conventional

hardness indentation testing, there are two important innovations. The

indentation is described by a load-displacement curve, and is performed

over a wide range of times, from hours to milliseconds.

In one project with ONR, we have studied the deformation behavior of an energetic material, RDX, respecting the magnitude and duration of loading.

We found a movable ductile-to-cleavage transition, which at fast impact

rates occurs at undetectably small loads. The use of energetic materials,

explosives and rocket propellants, require controlled ignition. Just why

a mechanical impact causes ignition is still unclear. A theory we are investigating recognizes that impact deformation causes dislocation

motion; and dislocation clustering causes ignition. Both the free motion

and piling-up of dislocations at internal obstacles are key factors. The

kinetic and/or self energies of dislocation strain fields are believed to

cause "hot spot" formation and subsequent ignition. A major theoretical

factor is the two competing deformation modes, plasticity and cleavage,

and our mechanical studies will shed some light on these processes.

Recent modifications to the Dynamic Microindentation Instrument include a microscope for locating indentation sites, further reduction of the

working applied load range to 0.01 N, and use of an improved displacement

gauge. The microscope provides the means to indent specific sample

features to within +/- 3j^m. The improved displacement reduces systematic

errors and increases signal sensitivity by a factor of 60X, permitting

greater precision of depth determination.

In another project composite materials are being studied to determine

whether interfacial zones can be shown to contribute or detract from the

overall performance of metal matrix composites. A schematic of one physical model we are developing is shown in figure 3. Assumptions

implicit in this model are that all three zones occupy a significant

fraction of the total system volume, and that interfaces form at the

expense of matrix volume. Recent work by Arsenault and Flom (University

of Maryland) plainly show that this is the case for thermally consolidated

composites. A basis for quantitative evaluation of the contribution of

interfaces in strengthening composites is given by the following equation

as applied in our model:

Tensile Strength^^ = AV f (df t-t 2

) (TS i -TSm

)/dIT1 2

33
where = fiber diameter, t = interfacial zone thickness, = diameter

of matrix cavity, Vf = fiber volume fraction, TS^ = interfacial zone

strength, and TSm

= matrix tensile strength.

Presently measurements are underway in several prototype composites to

examine this approach.

Pressure Vessels

Research is carried out on metallic and composite pressure vessels used in

the transportation of high pressure gases. During the present year tests

were continued to develop suitable fracture criteria for the safe

construction of ultra high strength steel, thin walled cylinders. A

publication of these results is in preparation jointly with M. Rana of

Union Carbide Corp. This project also includes technical assistance to

the Office of Hazardous Materials in the Department of Transportation to

develop safety standards for the use of such vessels.

Work is continuing to develop a suitable test method for inspecting large,

seamless steel cylinders using a combination of acoustic emission and

ultrasonics. To date, a large number of cylinders have been tested using

several acoustic emission procedures. These studies are being done

jointly with Union Carbide Corporation, Linde Division, Tonowanda, NY, and

FIBA, Inc., Westborough, MA. Although many defects have been detected

with these procedures, the detectability of specific defects has not been

clearly established yet/ Work is continuing to refine and develop the

inspection procedures and to establish a reliable procedure for inspecting

cylinders by acoustic emission methods.

Fine, intergranular cracks have been found in the neck/ thread area of type

3A1 aluminum and composite aluminum seamless cylinders. An investigation

is ongoing to determine the extent and significance of these cracks and to

develop a reliable inspection technique for finding the cracks. The

cracking is believed to be a form of room temperature creep cracking that

is enhanced by temperature, stress, and environment; research is

continuing to establish the responsible mechanisms.

Metallic Surgical Implants

Subtask 3

A. C. Fraker

This project maintains a laboratory for the study of metallurgical aspects

of surgical implants. Implant problems come to our attention due to

failures in service, during the evaluation of selected metals for implant

use, and in analyzing the metals used in terms of optimum quality.

Studies conducted include microstructural characterization, surface film

analysis, corrosion testing, and mechanical property measurements. The

laboratory is equipped with computerized corrosion and mechanical testing

equipment. The project has, for the past fifteen years, developed

literature reference files on the use of metals as surgical implants.

Recently, these files have been expanded to include selected references on polymers and ceramics. The files contain 1450 reference papers.

34
Electrochemical Measurements

Studies were continued on the effects of varied surface treatments and the

oxidation state of metal ions released during corrosion. Anodic

polarization measurements were made on Co-Cr-Mo at 37 C in Hanks'

physiological saline solution, 0.9% saline solution, and serum

(NBS SRM 909). There was a significant increase in current in the passive

region for tests in the saline solution. The breakdown potential was nearly the same in all three solutions. Chemical analyses after corrosion

testing were tarried u^jlng atomic absorption methods to determine the

amounts of Cr and Cr presenlj.^ The data show both types present in the

saline solution but only the Cr in the serum solution. The nature of

the Cr ion release will be studied further since it bears on the

biocompatability of metal implants.

Anodic polarization measurements on arc plasma sprayed porous coated

Ti-6A1-4V were made in Hanks' physiological solution at 37 C. Results

showed that grit blasting surface preparation procedure greatly reduces

the corrosion resistance and results in a lower breakdown potential of

0.65 volts vs. the saturated calomel electrode (SCE). The breakdown

potential for Ti-6A1-4V is 2.5 volts vs. SCE. Breakdown potentials for

grit blasted and sintered, and for arc plasma spray coated fall

intermediate within these two extremes. Energy dispersive x-ray analysis

showed the presence of iron, silicon, and additional aluminum on the

surface of the grit blasted material. These results demonstrate the

importance of controlling all parameters to prevent contamination during

the plasma spraying process.

Corrosion-Fatigue

Studies of effects of sintered porous coatings on corrosion fatigue

behavior Co-Cr-Mo were investigated. Three types of specimens were

prepared; the as cast condition, sintered without the porous coating, and

sintered with layers of spheres to produce the porous coating. Specimens

were subjected to fully reversible torsion tests with applied shear strain

amplitudes ranging from +/- 0.003 to +/- 0.006 at a frequency of 1 Hz in

flowing Hanks' physiological saline solution at 37 C and a pH of 7.2. The

results are shown in figure 4 where the data on porous coated Co-Cr-Mo

material is compared with earlier work on hot isostatically pressed,

forged and cast Co-Cr-Mo. The materials seem comparable when torsion

tested with an applied shear strain amplitude of +/- 0.006 but the

endurance limit for the porous coated material, (0.003) was less than that

for the nonporous material, (0.004).

ASTM F-4 Committee on Medical and Surgical Materials and Devices

The project contributes to standards activities through the Metallurgical

Materials Section which develops specifications and standards for metals

and alloys to be used as implants. Other F-4 sections of principal

interest are the Joint F-4/G-1 Corrosion Section and the Porous Metals

Section where we have provided leadership in symposia and standards

development

35
Figure 1. The rise in friction to Figure 2. Plot of average roughness

steady state for reciprocating (Rt) values versus load for

sliding using a 52100 steel ball pin-on-flat galling wear tests,

on a polished Cu-15 wt%Ag flat.

Load 4.91N, sliding velocity

5 cm/s, in argon.

Figure 4. S-N curves for Co-Cr-Mo in

the cast (o), forged or hipped (x) and

sintered porous coated (A) conditions.

Figure 3. Schematic showing three Reversible torsion tests conducted in

regions affecting mechanical Hanks' solution, 37 C, pH of 7.2,

behavior in a composite. frequency 1 Hz.

36
CHEMICAL METALLURGY James G. Early/ John B. Clark

The principal activity of this task 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 three binary category editors (titanium, aluminum, and iron)

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 20

ternary category editors participating in this program. During the past

year, the three NBS category editors completed evaluations on thirteen

titanium, seven aluminum, and three iron systems. The titanium binary

alloys systems have now been completed and publication of the evaluated

titanium phase diagrams as an ASM monograph is in process.

A major effort was initiated in 1985 to digitize 1578 binary phase

diagrams for the new ASM compendium updating the compilations of Hansen,

Elliott and Shunk. This project has been successfully completed in FY86.

Crystal structure and other ancillary data are now being computerized and

binary system graphics and numerical data are being loaded into an on- line database.

The experimental efforts in support of the alloy phase diagram continued

with emphasis on binary and ternary Al-based systems. Rapid

solidification and stable and metastable phase equilibrium studies have

been completed for the Al-Mn system. Studies are being carried out on the

Cu-Mn system (in relation to the Al-Cu-Mn and Al- transition metal binary

systems )

Other activities in this task include an experimental program to improve

standards for magnetic particle inspection and dye penetrant testing, and

to evaluate the need for standards and specifications in the field of

Barkhausen Noise NDE. These efforts involve substantial interactions with

standards writing organizations such as ASTM.

FY 86 Significant Accomplishments

o Theoretical and experimental results in the area of magnetic

particle inspection led to the incorporation into a new military

standard of a new methods for using Hall-effect probes to

determine proper magnetization levels for effective inspection.

o A program of evaluation of Al-based (Al-Cu-X) systems has been

initiated

37
o Thermodynamics optimization programs have been extended to make use

of new Gibbs energy models and optimization algorithms and a user- friendly interaction thermodynamics optimization program has been

implemented for ternary systems.

o A workshop on the phase diagram database was held to introduce the

database to potential users.

Alloy Phase Stability

L. K. Charlton*, D. J. Kahan, R. M. Hayes, L. F. Lilly*, A. J. McAlister,

J. L. Murray, C. E. Sirofchuck*, H. E. Rubin, L. J. Swartzendruber , C. L.

Qualey*, L. B. Wilkinson, D. L. Moffat, and U. R. Kattner

*American Society for Metals Research Associate

We are pursuing a program of four interconnected parts: critical

evaluation, compilation and thermodynamic modeling of binary phase diagram

data; designing and setting up a prototype database for on-line retrieval

of the graphical and numeric phase diagram and ancillary data of the

(crystal structure, lattice parameters); experimental work on phase

stability of alloy systems, selected with a view a complement the

evaluation program; and the theory of phase stability.

Alloy Phase Diagram Data Center Activities

All activities revolve about a collaborative data evaluation program for

alloy phase diagrams with the American Society for Metals. At NBS, the

scope of the phase diagram program has been greatly extended. 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, Joanne L. Murray for Titanium alloys, Archie J. McAlister

and Joanne L. Murray for Aluminum alloys, and Lydon 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 form thermodynamic data are carried out using a number

of computer programs available at NBS.

In addition, the data center staff are responsible for technical editing

and graphics digitization for the Bulletin of Alloy Phase Diagrams, and

for prototype database project, the editing and computer graphics for a book, the Binary Alloy Phase Diagrams, which is to update the compilations

of Hansen, Elliott, and Shunk.

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

of six issues per year. Technical editing of manuscripts is done by the

editor, J. L. Murray; C. E. Sirofchuck supervises the entry computer of

graphical and crystal structure data.

In preparation for making the phase diagram database commercially

available, a workshop was held to familiarize potential users with the

38
database. Attendees of the workshop were from major U.S. corporations,

IBM, General Electric, Allied Corp. , etc. A manual for the use of the

database was written by Jim Sims and Joanne Murray to facilitate the

user's application of the database. The attendees operated the database

with the assistance of J. S. Sims, J. L. Murray and J. B. Clark. The

database was well received. Final changes in the database were made at

the suggestion of the participants. A typical search is shown on the last

page of the Chemical Metallurgy Group report.

Experimental Phase Diagrams and Related Thermodynamic Calculations

A major fraction of the past year's effort was devoted to the completion

study of the complex, recrystallization and quasicrystalline icosahedral

and T phases formed on rapid quenching of A1 rich Al-Mn alloys. Heats of

transformation and activation energies have been determined by

differential thermal analysis (DTA), and the phases occurring during the

process by x-ray diffraction and transmission electron microscopy. Apart

from their inherent interest, these results have proved most useful in the

evaluation of the Al-Mn phase diagram. Metastability of the Al^oMn3 phase

was confirmed and that of 'Al^Mn' established. Certain other features of

recent experimental studies of the system were confirmed. The measured

heats of transformation facilitate modeling of the non-equilibrium phases

and permit estimates of the true liquidus in this region of the diagram to

be made. Thermodynamic calculations of Al-Mn have produced a complete

catalog of metastable invariant reactions that may occur during cooling

from the melt. A peritectoid reaction was predicted by the thermodynamic

calculations and confirmed by thermal analysis experiments.

The topological similarity of the Al-rich Al-Cr and Al-Pd systems, in

which the icosahedral phase is known to occur, as well as Al-Mo, Al-V and

Al-W strongly suggest that these systems too may contain long lived

metastable phases, and that their presently accepted equilibrium diagrams

are incorrect. A systematic study of metastable equilibria in Aluminumtransition metal systems has been completed and a data evaluation of Al-Cr

is in progress. The extension of metastable equilibria into ternary

systems is also of current interest. Thermodynamic calculations have been

made of the Cu-Mn and Al-Cu-Mn and experiments on the Cu-Mn binary systems

are underway to resolve discrepancies found by means of the model

calculations. No evidence of the reported Cu3Mn or Cu5Mn phases have been

observed using DTA; interpretation of the reactions that are seen in DTA

is in progress. The Al-Cu-Li system is extremely difficult to study

experimentally, because of reactivity of the alloys and the high vapor

pressure of Li. Strategies for overcoming these difficulties are now

being planned.

Expansion of our DTA capability is underway. Equipment is being acquired

which will raise the maximum achievable temperature from 1200°C to 2000°C.

Moreover, the equipment is being tailored to permit use of the Dils

blackbody temperature sensor in lieu of the traditional thermocouples.

This will enable more precise determination of transformation temperatures

in the 600°C to 2000°C range, and offer improved accuracy in the heats of

transformation there, as well as expanding the scope of our work.

39
Several items have been acquired to enable us to melt and heat treat high

purity alloys. An arc melter was salvaged, cleaned and refurbished, and

tested by melting a titanium ingot. Three furnaces capable of achieving

800°C were refurbished and the temperature gradient profiled. New

programable controllers were purchased for the furnaces.

A substantial effort has been made this year to improve and update the

computer programs for thermodynamic calculations and graphical display.

For binary systems, more sophisticated models for compound free energies

have been implemented and an improved user-friendly interface was written.

For the first time, a program of similar power is available for ternary

calculations. A variety of unit transformations and graphical

representations of ternary sections and projections can be made using

software that interfaces to the two dimensional phase diagram graphics

program.

Magnetic NDE

A variety of magnetic methods are available for nondestructive evaluation,

both of defects and of material properties. A number of these, such as magnetic flux leakage, magnetic particle inspection, and eddy-current

testing, are widely used in industry, primarily for detection of defects.

Some other methods have been used on a limited scale but still require

development to make them more reliable and more widely applicable. These

include: Barkhausen noise, magnetoacoustic emission, magnetomechanical

damping, and ac magnetometry . Finally, magnetic property measurements,

including saturation magnetization, coercivity, and initial permeability,

contain a wealth of information concerning material properties that has

barely begun to be exploited.

To date, this project has been primarily focused on magnetic leakage field

methods, especially the magnetic particle methods, and on Barkhausen noise

measurements. However, further progress in the use of magnetic methods,

especially as applied to the measurement of material properties, will

depend on improving our understanding of how the measurement of magnetic

properties correlates to material parameters such as alloy composition,

heat treatment, stress, states, etc. It is clear that a multivariate

approach will be required. That is, two or more magnetic properties can

be expected to yield useful information, such as grain size, where a single property measurement would give such information only under very

restricted conditions. To this end, the Metallurgy Division has been

expanding its ability to perform magnetic measurements, both

nondestructive evaluation and for other purposes. During the present

year, a vibrating sample magnetometer has been put into operation and is

in the process of being computerized. Also, a unique automated ac susceptibility apparatus has been developed. The latter instrument allows

the measurement of initial magnetic susceptibility over a frequency range

of 20 Hz to 100 kHz. A unique feature is the ability to measure both the

real and the imaginary parts of the susceptibility over a wide temperature

range. Initial studies are expected to center on the correlation of ac susceptibility, coercive force, and Barkhausen noise with the

microstructure of iron-carbon alloys.

40
In cooperation with Sandia National Laboratories, a report has been

prepared on the NDE of large castings by surface methods. Surface methods

include visual inspection, magnetic particle inspection, dye penetrant

inspection, eddy-current inspection, leakage field measurement, hardness

measurements, and Barkhausen noise measurements. Primary emphasis was on the magnetic particle method because this is the most used method for the

inspection of large castings. This report will be combined with two

others, one on ultrasonic methods and another on radiographic methods to

be used as a resource document for the inspection of large storage casks

for the nuclear industry. A talk was given on this report at a Cask

Material Technology Seminar held at NBS in December, 1985.

Work has continued in cooperation with ASTM committee E7 and the Standards

Subgroup of the JTCG-NDI an improvement of magnetic particle inspection

standards. A major problem with both the ASTM standard (ASTM E-709) and

with the new military standard (MIL-SID-1949) is the tool steel test ring

currently used to verify magnetic particle performance of such rings. An

attempt is being made to select a steel and a heat treatment which will

reduce the variability in performance of the test rings. Further, even

when such variability is reduced to acceptable levels, the currently

specified test ring does not do an adequate job of testing the ability of

particles to detect narrow cracks. The design of a new test device is

being planned.

41
EXAMPLE OF A SEARCH IN THE METALLURGICAL PHASE DIAGRAM DATABASE

Using the "Phases" relation of the database, the search is made for all

phases that fulfill the following conditions:

(a) The phase is a congruent melting phase

(b) The phase is Cubic - all faces centered (Pearson symbol

contains cF

)

(c) The prototype is not Cu

The selected data is sorted by Prototype.

Select what <ALL>?

Sorted by <NONE>?proto

Conditions <NONE>? ty[p] eqs congr and

And?prson eqs cF and

And?proto ne Cu

Search Results -

ASYST PH STRKB PROTO PRSON SG E Mg—Ge Mg2Ge Cl CaF2 cF 1 2 Fm3m © Cu-S Cu<2-de 1 ta>S Cl CaF2 cFI 2 Fm3m e Cu-Se be t aCu<2-x>Se Cl CaF2 cFI 2 Fm3m © Mg-Sn Mg2Sn Cl CaF2 cFI 2 Fm3m e Mg-Si Mg2S i Cl CaF2 cF 1

2

Fm3m © Mg-Pb Mg2Pb Cl CaF2 cFI 2 Fm3m © A 1 —Ho A 1 2Ho C15 Cu2Mg cF24 Fd3m © Al-Lo A 1 2Lo Cl 5 Cu2Mg cF24 Fd3m © A 1 —Gd A 1 2Gd CIS Cu2Mg cF24 F d3m e Mg-Cu MgCu2 Cl 5 Cu2Mg cF24 Fd3m e A 1 —Sc A 1 2Sc Cl 5 Cu2Mg cF24 Fd3m e N i —0 beta B1 NoCI cF8 Fm3m e Co-0 CoO B1 NaCI cF8 Fm3m © V-C VC B1 NaCI cF8 Fm3m e Sb-U SbU 81 NoCI cF8 Fm3m © Al-li Al Li B32 NaT 1 cF 1 6 Fd3m © A 1 —As A 1 As B3 ZnS( spha 1 e r f t*e) cF8 F—43m © A 1 —

P

AIP B3 ZnS( spha 1 e r i t e

)

cF8 F—43m © Al-Sb AlSb B3 ZnS( spha 1 e r i t e

)

cF8 F-43m ©

At the time of the search (Jan. 26, 1986) the "Phases" relation contained

data on 1267 phases, as shown above, nineteen phases fulfill the above

conditions

.

42
CORROSION AND PROTECTION OF METALS Ugo Bertocci

The purpose of this task is to investigate the effects of metallic

corrosion, one of the major causes of the shortening of service life of

all metallic structures from ships to bridges to pipelines, and whose

cost to the US economy is estimated in the 10^ $/year range. Corrosion

is often a contributing factor in catastrophic failures, whether of

chemical plants or prosthetic devices, with consequent loss of life and

property.

The work done under this task in FY 1986 has continued to be directed to

four main areas: 1) basic research on the mechanism of the major forms of

corrosion, 2) development of measurement techniques 3) dissemination of

literature data on corrosion and 4) studies of corrosion problems arising

from the disposal of high level nuclear waste.

Stress corrosion cracking (SCC) has been the major subject of fundamental

research during FY86. The cause of SCC is very poorly understood and

there is still debate whether there is only one or several different

mechanisms for it. In practice it limits the use and degrades the performance of many engineering materials, ranging from copper and aluminum

alloys to stainless steels.

Based on the extensive experience of the Corrosion Group on measurement

techniques both in the laboratory and in the field, our efforts in the

area of measurement have resulted in the construction of a device for the

in-situ corrosion testing of steel in concrete structures. Its performance has been assessed in the laboratory by comparing it with other

measurement methods, and it is undergoing field testing. In the area of

localized corrosion, electrochemical noise techniques applied to pit

initiation are being tested by developing software for statistical

analysis

The joint NACE-NBS program for the institution of a Corrosion Data Center

has seen further development in FY 86. This program was initiated in

response to a clear need for a central source of reliable corrosion data

and for the employment of computer-based media for their dissemination.

The activity of the Corrosion Data program has been strengthened by the

addition of new staff and by increasing cooperation with industry and

other organizations.

Our activity in assisting the Nuclear Regulatory Commission with corro- sion problems associated with the development of geological repositories

for high level nuclear waste has grown considerably during FY86. This

has entailed an expansion of the personnel involved in this effort. This

activity concerns a critical national problem with timetables set by

congressional order: metallic containers of highly radioactive materials

have to be buried at several geologic sites and are expected to withstand

corrosion for times well in excess of present industrial experience. The

assessment of the problems involved and the estimation of the chances of

successful isolation of the radioactive waste pose a very challenging

task.

43
FY 86 Significant Accomplishments

o Mechanistic studies of SCC of a -brass and A1 alloys have

continued. Fractographic and electrochemical measurements

have indicated that certain proposed mechanisms for brittle

fracture may not be valid.

o A system for the simultaneous measurement and analysis of AE

signal during SCC tests has been assembled and successfully

tested. Preliminary experiments on stainless steel specimens

have been carried out.

o Computer-encoding of NACE Corrosion Data Survey completed.

o Selection of hardware and development of software of DBM of

high level nuclear waste completed.

Environmentally Induced Cracking

Subtask 1

Stress Corrosion Cracking

E. N. Pugh, U. Bertocci, T. Cassagne^, J. Fink, M. Kaufman, H. Lai^

R. Ricker, R. Rothea^, M. Stoudt, A. Van Orden, S. Ventura.

1 Guest Scientists from France

^ Guest Scientist from Taiwan

Our stress corrosion cracking (SCC) studies in FY86 have resulted in some potentially significant findings. First of all, it has been shown that

cracking of a -brass in aqueous ammonia solutions does not occur in the

absence of anodic dissolution of copper. In these conditions the fractures appear ductile indicating that dezincif ications is not sufficient

for cracking. Furthermore, when a very slight amount of dissolution of

Cu is allowed, the cracking, though localized, appears very different

from the "cleavage-like" fractures typical of a -brass in cupric ammonia

solutions. This result casts serious doubts on the brittle "microcleavage" mechanism for cracking. Finally, TEM observations of regions

adjacent to the fracture surfaces of samples tested in cupric solutions

at low stresses revealed that very little deformation accompanied the

cracking process in contrast to that expected for either the microcleavage or the slip dissolution mechanisms.

Our work on high strength Al-Zn-Mg alloys correlate directly with the

a- brass/ammonia results. For example, it has been found that cracking

in these alloys occurs for a wide range of microstructural conditions.

However, the "cleavage- like" fractures are observed only in those conditions where the slip is coplanar, as shown by TEM analysis, due to the

precipitate distribution and, for those conditions, is most prevalent at

the largest precipitate sizes. In severely overaged material where the

slip is no longer planar, the fractures are not cleavage-like but take on

a very complex geometry. In addition, TEM analysis of the material

44
adjacent to the cleavage- like fracture surfaces revealed that, again,

very little deformation appeared to accompany the cracking process.

According to some mechanisms for T-SCC in ductile metals recently proposed, a surface layer differing in mechanical properties from the bulk

metal is necessary for crack initiation. Dealloying may be one way to

generate the surface layer. However, pure Cu also undergoes T-SCC, as it

has been shown in nitrite solution. Cracking in this case is associated

with the formation of a thick cuprous oxide film. It was therefore

interesting to see if T-SCC could be induced in pure Cu in the absence of

the film, possibly in a nitrite solution of suitable acidity. Since the

electrochemical behavior of Cu in nitrite solutions is not well known, it was necessary to carry out polarization studies in various conditions.

Extensive data have been collected and some of the electrode reactions

identified. However, these studies have shown that it is impossible to

prevent film formation without destroying the nitrite in solution.

Therefore, SCC tests on Cu single crystals are now being carried out in

sulfate and acetate solutions, where oxide film formation can be prevented. Preliminary results show that T-SCC can be produced in these

solutions, with average velocities of the order of 10”-*-^m/s. More tests

are underway to improve control of the cracking process so as to

accelerate crack propagation and to perform f ractographic studies.

The analysis of acoustic emission (AE) signals for the monitoring of SCC

and for discriminating among different forms of attack is being applied

to austenitic stainless steels in MgCl^ solutions, both during slow

strain rate and load pulsing tests. Assembling and testing of the

instrumentation has been completed and the experimental work initiated.

In a closely related project, sensitized stainless steel is being

examined by AE and electrochemical measurements to test the usefulness

of AE as a diagnostic tool.

In the past years efforts have been made to model mathematically the

electrochemical and transport processes occurring within crack for Cubase alloys. The work has been extended to see if calculations could

explain the experimentally observed transition from intergranular to

transgranular cracking. However, it became soon obvious that the value

of the kinetic parameters involved are not known with sufficient cer- tainty to allow confidence in the numerical results. As a consequence,

an experimental effort has been initiated to measure the electrode

kinetics of copper in aqueous ammonia solutions. The initial results on the anodic dissolution of Cu to CuCNH^^"1" ions have indicated that this

part of the process occur with relatively low hindrance for the chargetransfer step.

Hydrogen Embrittlement

C. G. Interrante, S. Harrison, M. Stoudt

The objective of our work on hydrogen embrittlement is to relate the

measurable effects of hydrogen, such as crack growth rate for various

stress-intensity (K) levels and the threshold value of K for hydrogenassisted cracking, to the driving force (the fugacity of hydrogen

45
associated with a given metal/environment system) and to the important

metallurgical factors, such as hardness and inclusion size, shape, and

orientation. These relationships will be useful in predicting conditions

under which cracking is to be expected, as well as in the development of our understanding of the cracking process, which may lead to theoretical

models describing the mechanism of hydrogen embrittlement. In our program, the effects of hydrogen are assessed with fracture mechanics

specimens of steels used commercially in the petrochemical industry, and

with severe hydrogen-charging environments containing hydrogen sulfide,

a common contaminant found in that industry.

In cooperation with the Nondestructive Characterization Group, electric

resistance measurements of crack length are coupled with acoustic

measurements of strain energy released during crack extension. The

results indicate that is possible to estimate the magnitude of the crack

extension and of the fracture area associated with each acoustic emission

from the acoustic emission alone. It is expected that this sensitive

measurement of crack extension will help in understanding the cracking

process and the mechanism of embrittlement.

A new computer and a servo-hydraulic test system have been installed

for conducting fracture mechanics tests that require complex loading,

such as the J- integral and constant K. Last year, computer codes were

written and techniques developed and implemented for the measurements of

acoustic energy and crack length, and this year tests were conducted to

assure the adequacy of these computer codes. These studies of hydrogen

embrittlement of steels have been conducted under the guidance of the

Subcommittee on Hydrogen Effects of the Pressure Vessel Research

Committee (PVRC) of the Welding Research Council (WRC).

Corrosion Rate Measurements for Practical Applications

Subtask 2

E. Escalante

Corrosion of Steel in Concrete

The final phase of this project, which included corrosion measurements of

reinforcing bars in concrete bridge decks, has now been completed. A

portable, battery operated, corrosion measuring device was assembled and

tested in the laboratory, and the data obtained were compared with weight

loss measurements. The results indicate that polarization resistance

measurements could be used to measure corrosion of steel in concrete.

Field measurements although still preliminary, also appear to be

successful. The corrosion data gathered in the field correspond very

well with the history of the structures and agree with visual inspection

of the bridge decks. Thus, where our measurements indicate high

corrosion, we can, indeed, see evidence of corrosion. It was interesting

to find that a relatively new bridge (12 years old) was corroding at a higher rate than an older bridge (54 years old).

46
Steel Piling in Soil

This long term program studying the corrosion of steel piling in soil is

continuing under the sponsorship of the American Iron and Steel

Institute. The corrosion measurements, made annually, show that the

piling in undisturbed soil are corroding at a much lower rate than those

piles in backfilled, disturbed soil. For the second year, these

measurements were made using portable computerized equipment in addition

to the usual manually controlled methods.

Corrosion Data Center

Subtask 3

G. M. Ugiansky, D. B. Anderson, D. E.Clausen^, C. D. Flanigan, T. Flax,

and E. D. Verink^.

1 NACE Research Associate

^ Guest Scientist, University of Florida

The focus of activities this year in the NACE-NBS Corrosion Data Center

has been in two primary areas: (1) the completion of the first output of

the data center -- a distributed database; and (2) arranging for the

acquisition of industrial corrosion databases.

The distributed database has been completed and is being issued by NACE

as a floppy disc package for personal computer use. The package, called

CORSUR Vol. 1, is a software version of NACE's Corrosion Data Survey - Metals. The software allows the user to search and sort the data by

specified environment (over 1000 included) with defined concentration and

temperature constraints and to call up the more than 25,000 graphs.

Substantial progress has also been made on Vol. 2, a companion volume on nonmetals

In an effort to acquire industrial corrosion databases, arrangements have

been for the transfer of digitized field corrosion data from the LaQue

Center for Corrosion Technology, and with Battelle Columbus Laboratories

and Cabot Corporation for additional data.

Nuclear Waste Disposal

Subtask 4

C. G. Interrante, U. Bertocci, T. Coyle, E. Escalante, A. Fraker,

S. Harrison, M. Kaufman, W. Liggett, M. Linzer, H. Ondik, E. Plante,

E. N. Pugh, R. Ricker, R. D. Shull, M. Stoudt, and G. M. Ugiansky

Two programs on nuclear waste disposal are supported by the Nuclear

Regulatory Commission. A program begun in FY85 in support of NRC's

High Level Waste (HLW) Management Program, the NBS assists the NRC by

evaluating the Department of Energy (DOE) activities on waste packages

designed for use in a permanent repository of disposing of radioactive

waste from nuclear power plants and other sources. The work involves

47
conducting formal reviews of the research and development efforts of

the DOE Waste Package Program, as well as rendering informal technical

opinions on numerous issues, attendance at meetings, interaction with the

international community and, in general, development of a broad understanding of the present and planned DOE activities, such as those on test

methods, design of experiments, and theoretical and modelling efforts.

The work involves workers from throughout the Bureau. Major problems

threatening the integrity of the waste package include pitting, stress

corrosion cracking, and hydrogen embrittlement, which are the main thrust

of the Corrosion Group. Work in the area of leaching of borosilicate

glass is supported in part by members of the Ceramics Division. The

program is supported by statisticians and modelling specialists from the

Center for Applied Mathematics.

During FY86 formal reviews of over 30 pertinent documents will have been

carried out. NBS recommendations for hardware selection and proposals

for the management of the database on HLW, together with specific software developed for the purpose have been approved by NRC and are being

implemented. Since an important objective is to identify additional

data and types of tests needed to demonstrate that the DOE waste package

designs will meet NRC performance objectives, proposals for laboratory

work to be conducted by NBS in support of this objective have been submitted and are currently under joint NBS/NRC review, with the expectation

of initiating this work at the beginning of FY87. Our assistance to NRC

has also required participation of NBS staff to several meetings both in

the USA and abroad.

The second program sponsored by the NRC Office of Nuclear Regulatory

Research concerns the statistics of pitting, a form of localized

corrosion of great concern for the performance of the high level waste

containers. Studies have continued during FY86 to develop software for

the processing of the current fluctuations observed during the period

which precedes the formation of active pits. The results of this

analysis are being compared with the predictions of a stochastic model

for pit initiation, based on the idea that local breaks of the protective

film require a certain time to repair, so that a limited memory affects

the breakdown probability. Also, measurements of pits formed on large

steel sheets, and statistical analysis of their distribution is being

pursued in cooperation with the University of Manchester in the United

Kingdom.

48
ELECTRODEPOSITION

(ELECTROCHEMICAL METALS PROCESSING) David S. Lashmore

The Electrodeposition Group is responsible for measurements and standards

associated with electrodeposited pure metals and alloys. The objectives

of the group are: (1) the determination of the critical mechanistic,

material, 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 coating thickness standards, microhardness 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 expertise to industry, through research associates and standards organizations, and to other 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 indicates that in many applications

coatings can replace bulk stainless steels. (2) Corrosion - coatings are

the most common form of corrosion protection. It has been estimated that

the cost of corrosion to the U.S. economy is about 70 billion dollars per

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

to be from 30 to 50 billion dollars per year. Electrodeposited coatings

play an important role in improving wear properties and surface coatings

can be optimized for wear. (4) Custom tailored alloys - Provide new kinds

of materials with tailored microstructures which cannot easily be produced

by other types of materials fabrication technologies, such as artificial

superlattice structures designed for improved magnetic, superconductive

properties or mechanical properties.

Electrodeposition is one of the few metals processing techniques that

virtually provides atomic control over composition and structure. This

technology has been exploited for many years without an in-depth understanding of the process or the morphology of the alloys when applying

coatings for wear and corrosion protection and to electroform large items.

It seems clear that development of such an understanding would provide

information leading to very new and unique types of material.

FY 86 Significant Accomplishments

o Completion of a mathematical model of the deposition of alloys onto

fibers. This modeling process implemented an expression for the

boundary layer behavior on fibers moving in electrolytes used for alloy

deposition and adapted this knowledge to the existing mathematical

model of the deposition process. This model is now used to help design

a pilot plant to produce small quantities of aluminum alloy coated

fibers to hot process into metal matrix composites for subsequent property measurement.

o Artificial superlattice structures of Cu-Ni and Cu-Co have been pro49
duced from a single electrolyte. The first evidence of x-ray satellites on all principal planes has been presented for Cu-Ni indicating

perfection of structure on nearly an atomic level. A technique has

been developed for tailoring waveforms to produce sharp interfaces on both the leading and the trailing edge of each layer. The first pure

metal-metallic glass (Ni/Ni-P) composition modulated alloy has been

produced from a single electrolyte. Composition modulated alloys of

Cu-Ni, Cu-Co, Cu-Fe, Sn-Ni, Cu-Ni-P, and Ni-NiP have been produced to

date

.

o New techniques for tailoring interface regions have been developed

making use of artificially layered structures whose layer spacing is

deliberately increased as a function of distance or whose composition

is gradually varied according to a predetermined schedule.

o Developed and produced 270 microhardness standards certified at loads

of 25 g, 50 g, 100 g, 300 g, 500 g, and 1 Kg. Hardness ranges were 125

Kg/mm 2 and 500 Kg/mm

o Developed new wear resistant chromium and chromium alloy coatings using

both direct and pulsed current deposition. Significantly, pulse parameters were determined that yield a "low contraction" chromium produced

at the same operating temperature as the ordinary microcracked chromium.

o Developed the technology for electrodepositing aluminum and aluminum

alloys (Li, Mn) and characterized some of the electrochemistry operative in this electrolyte.

o Three patents or patent disclosures were filed.

1. Room temperature technique for production of composition modulated

alloys using a cold rolling process. (disclosure)

2. Patent on automated microhardness measuring system. (application)

3. Patent filed on trivalent chromium deposition. (application)

Mathematical Modeling of Alloy Deposition on Moving Fibers

Subtask 1

C.R. Beauchamp, D.S. Lashmore

The algorithm of the mathematical model previously developed for the electrodeposition of alloys on rotating disk electrodes has been modified to

accommodate a new geometry and electrolyte flow. The new system of interest is that of a thin wire or fiber moving along its axial direction

through the electrolyte as shown schematically in figure 1. The treatment

of the new system was divided into three stages. First, the treatment of

the flow of the solution was modified to accommodate the different convection mass transport and a new boundary profile predicted. Second, the

model was extended to a two dimensional analysis since it is required for

the prediction of the current distribution due to the IR drop caused by

high resistivity of the fibers and due to the changing boundary layer

thickness. Last, an attempt to significantly reduce computation time by

means of an upgraded finite element method for the solution of the partial

differential equations using the Crank Nicolson method. As part of this

50
project, a thin flow cell that enables the visual inspection and video

recording of film formation and crystal growth has been designed and con- structed. The cell enables the study of the effects of addition agents on the mechanisms of film formation and crystal growth on a real time basis

during the process of electrodeposition. The cell consists of a plating

chamber with a channeled thin flow of electrolyte (about 25 microns thick)

placed under a microscope equipped with a video camera that enables specimen inspection during the experiment. The image of the specimen can be

displayed on a television screen or recorded using a video cassette.

Wear Resistant Coatings for the Engraving Industry

Subtask 2

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

A study of the electrodeposition of engraved currency printing plates for

the Bureau of Engraving and Printing (BEP) has been underway for two years

in collaboration with the wear group. The initial portion of this program

focused on developing an understanding of the process and process variables along with measurement of properties of the electroformed printing

plates. Subsequent investigation focused on the characterization of abrasive wear of various chromium electrodeposits and other metallic coatings under a simulated printing environment and in situ wear tests at

BEP. Some of the results of -this portion of the program on wear of various chromium deposits are shown in figure 2. The coatings were obtained

by direct current (DC) plating, galvanostatic pulse plating, varying operating parameters. The lowest wear rate from the abrasive wear instrument

used to rank coatings was recorded for "transition zone" chromium deposits. Recent literature has stated that the lowest coefficient of friction is also obtained for the "transition" zone chromium. The "transition" zone chromium lies between the bright, hard, microcracked chromium

and "milky" chromium. A new duplex chromium deposit shows promise in the

simulated environment. Galvanostatically controlled pulse plated deposits

resulted in similar wear as the BEP chromium. The majority of other me- tallic coatings investigated for wear in the simulated environment have

shown much greater wear than the BEP chromium with the exception of a composite coating of electroless nickel containing 3 micron sized particles of silicon carbide. The coating showed negligible wear (within the

range of detection).

Standard Reference Materials

Subtask 3

R.J. Brown, H.B. Nottingham, S.S. Wedemeyer, P. N. Sharpless,

and J.L. Mullen

Approximately 5000 coating thickness standards were produced this year. A

new computer program was written to use the raw data produced by the Beta

Back Scatter instrument for measuring the thick gold standards. Another

program was written to calculate the data obtained from the analysis of

the gold samples. These programs significantly improved our precious

metal measuring ability.

Implementation of a new set of stepping motors for the automation of the

51
coating thickness standards has been completed. The time required for

this phase of certification of the standards is reduced by a factor of 65%

due to the increased speed of operation of the new motors and to major

revisions to the software.

Microhardness standards of electrodeposited bright copper and nickel have

been in production for three years. Three new standards have been added

this year bringing the total available to seven. Nickel Knoop standards

are now certified for loads from 0.245 N (25gf) to 9.8 N (lOOOgf). A

patent application has been filed on the technique developed at NBS for

automating the microhardness measuring procedures. This same instrumentation shows promise of yielding micromechanical properties data (modulus

and yield strength) on very small volumes of material. The instrumentation has been developed to the point that it is capable of being used to

certify NBS microhardness standard reference material.

Metal Matrix Composites and Interface Properties

Subtask 4

D.S. Lashmore, C.R. Beauchamp, M.P. Dariel-', C.E. Johnson,

G.R. Stafford, S.A. Wright-Claggett , J. Yahalom**, R. Polvani***,

C . Handwerker***-'

Currently used technology for the production of metal matrix composite

materials (MMC) is not only expensive but has associated with it various

inherent problems included among which are reactions between the material

of the fiber and the matrix, low packing fraction of the matrix material

and the need to process the composite at high temperatures to consolidate

the fibers into a three dimensional structure. The technology addressed

by the study of MMC in this group is summarized in figure 3. In principle, a fiber or tow (large bundle) of fibers is coated with sufficient

material to supply the matrix when the fiber is hot pressed or otherwise

consolidated into a three dimensional structure. The technology provides

several very important advantages over powder metallurgy, casting, or other coating techniques such as (1) very high packing fractions because

the coatings can be made optimally thin, (2) diffusion barriers or adhesion promoting layers can be applied in a continuous process as can low

melting point eutectic coatings to promote consolidation, and (3) the

coating can be applied very rapidly to keep the cost low.

This comprehensive study of MMC* S is divided into 5 main areas: (1) the

investigation of the properties of aluminum alloys electrodeposited from

eutectic salt electrolytes; (2) a study of nucleation and growth;

(3) mathematically modeling the alloy deposition process on moving fibers

(discussed above); (4) investigation of the properties of alloys with

graded properties produced using electrodeposition techniques; and

(5) production of model composites for NDE characterization. Other areas

of activity under this program but described under other groups are a micromechanical properties measurement instrument (tribology) and thermodynamic modeling of interfaces (metals processing).

-'Guest Scientist, -'""Research Associate, ***Wear and Mechanical Properties

Group, ** -"-Metallurgical Processing Group

52
The Investigation of Aluminum Deposition from Molten Salts

G.R. Stafford and D.S. Lashmore

Aluminum and its alloys have been deposited from organic and fused salt

electrolytes. To date, there has been no successful process for deposition of aluminum from aqueous electrolytes. The processes using the or- ganic systems are reported to have poor throwing power at low deposition

rates. In addition, they usually contain toxic components and in some

cases, explosive components. Accordingly, this study focused on the development of a complete understanding of the properties of aluminum alloys

and their correlation with the deposition parameters from fused salt electrolytes. Successful processes for the electrodeposition of these alloys

at near 100% current efficiency and moderate deposition rates have been

reported in the literature.

These systems generally operate at the relatively low temperature of about

150 °C. These processes contain no toxic chemicals and are not explosive or pyrophoric. However, HCL vapor can be released in nonviolent fashion

under some circumstances. It was shown that in AlCl^/ NaCl melts, the

deposition process is limited by mass transport of Al? Ciy to the cathode.

The chronoaperograms of figure A show that at low overpotentials, the

current, and therefore the electrochemically-active surface area, does not

change with time. The deposits obtained under these conditions generally

have a low nucleation density. As the overpotential is increased, the

nucleation density improves significantly and finer grain deposits can be

obtained, figure 5. A further increase in the overpotential, however,

causes dendrite formation as seen by an increase in current as shown in

figure 4. Good deposits can be obtained from direct current plating at

moderate overpotentials where nucleation is favored, but limited mass

transport of AI2 CI 7 and therefore dendrite formation does not yet occur. Unfortunately, the highest current density obtained under such conditions

from the pure metal is only 20 mA/cm^. One method of promoting nucleation

without introducing diffusion problems is pulse plating. Very high cur- rent pulses on the order of milliseconds duration yield very dense, non- dendritic deposits. Though the overall current density is still limited

to that of the direct current case, deposition occurs under conditions of

enhanced nucleation which gives rise to much denser deposits. It has also

been shown that small additions of foreign metals or certain organics can have a dramatic effect on the morphology of the coating changing the tendency to form dendrites to a tendency to promote laterial growth, thereby

dramatically increasing overall current density (plating rate). In this

investigation, organics are avoided and the effort is focused on the addition of manganese chloride to accomplish this. Very bright deposits con- taining 25-35 w/o Mn have been obtained at 75 mA/cm*^ The microstructure

and mechanical properties of these deposits are presently being investigated .

Nucleation of Nickel and Copper on Graphite Tows

J. Yahalom and D.S. Lashmore

Metals are electrodeposited on carbon fibers for use in metal-matrix com- posites and for electrical applications due to the enhanced surface elec53
trical conductivity of the carbon-metal composite.

Nickel-deposited carbon fibers are commercially available. However, such

fibers may be objectionable for composite applications due to the formation of brittle carbide layers at the metal/fiber interface during sintering. Copper would therefore be more suitable for such applications.

There are a number of well established methods for the deposition of copper. It was found, however, that copper does not nucleate well on carbon

fibers and the resulting deposit is coarse-grained and non-uniform. We

have studied the nature and kinetics of the deposition of copper in com- parison to nickel and found that the initial applied potential has a decisive effect on the initial nucleation and subsequent growth of the deposits. It was found that by initially applying either a highly anodic or cathodic pulse, full coverage of the fibers is attainable. The mechanisms

for the two cases are different and we are presently investigating the

details of the nucleation process in relation to the fiber surface structure and properties and the effects of oxidation and reduction on these

properties

.

Electrodeposition of Artificial Superlattices

D.S. Lashmore, M.P. Dariel, and S. Wright-Claggett

Electrodeposition of artificial superlattices or microlayered alloys has

been under intensive investigation for the last two years and techniques

have been worked to electrodeposit Cu-Ni, Cu-Co, Cu-Fe, Sn-Ni and Ni-NiP

alloys, each from a single aqueous electrolyte. It was found that by

carrying out the deposition with a tailored galvanostatic waveform that it

is possible to produce materials with sharp interfaces on both the leading

and trailing edges of the layer and still maintain precise control of

the thickness of the layer. Studies of the morphology of coatings produced on single crystals have shown that the coatings are epitaxial on all

the principle orientations {100}, {110}, and {111}. However, only on {111} do the coatings maintain their epitaxy for any appreciable thickness

(at least 5nm). Because electrodeposition is essentially a room

temperature technology, there is reason to believe that the perfection

and sharpness of the interfaces between layers created by this technique

is much greater than that created by sputtering or vapor deposition for

which it is necessary to raise the temperature of the substrate to at

least 250 °C. One indication of perfection of the layers is the existence

of satellite peaks around the main Bragg peaks. These have been observed

for the first time on all principle planes of Cu-Ni. Examples of x-ray

data for Cu-Ni produced by tailored waveforms is shown in figure 6 and a typical TEM micrograph with ^=10 nm in figure 7. Techniques to measure

the elastic constants of Cu-Ni foils using ultrasonic techniques have been

developed in cooperation with Prof. M. Rosen of Johns Hopkins University,

but to date, there has been no evidence of supermodulus effects in the

as-deposited alloys, even though the layer spacing was comparable to sam- ples produced by vapor deposition which have demonstrated supermodulus

effects. These materials have potential for creating a region between

fibers and matrix whose mechanical properties can be graded at will, particularly the yield strength. Studies are also under way to measure the

magnetic properties, and the electrical and thermal resistivity.

54
Wear

Rate

x

1.0E+8,

g/cycle

Figure 1. A Schematic diagram of the geometry used for

modeling the deposition process on moving fibers.

Pulsed

Figure 2. Ranking of different chromium coatings using a simulated abrasive wear testing instrument.

55
Fibers

•SiC

• Graphite

1

Coating

Acts as a

Diffusion

Barrier

Multi-layered

Interface Region

to Distribute Strain

i

Matrix

• Aluminium

Lithium Alloys

Manganese

• Aluminium

Eutectic Coating Hot Pressing Product

Figure 3. Coating technology addressed in the investigation of metal

matrix composits and interfaces.

-0.05 V

-0.20 V

0.35 V

Figure 4. Chronoamperometry curves for single pulse

potentiostatic deposition on tungsten. Melt is a 2:1 mole ratio of AlC^rNaCl

56
Figure 5. Backscattered image (SEM, 36x) of aluminum electroplated onto

copper wire from AlCWNaCl melt. Six coulombs were passed at each of the

current densities: (a) 1.6, (b) 3.3, (c) 5.0 mA/cm .

Single [100] oriented Cu

57
Figure 6(c). Main Bragg peaks with satellites for the [111]

single crystal substrate. The [100] and [110] texture is small

on this orientation.

Figure 7. A typical TEM bright field micrograph (300 Kev).

The substrate is polycrystalline and the wavelength 10 nm.

i 1

100 A

58
NONDESTRUCTIVE CHARACTERIZATION Haydn N. G. Wadley

This task is concerned with the development of basic nondestructive

measurement methodologies and their application to the characterization

needs of materials science. The "pull" for this research area stems from

the emerging needs for (1) sensors for implementing new process control

scenarios, and (2) insitu measurement techniques for fundamental study of

transformation and damage mechanisms. The "push" comes from the recent

advances made in the measurement science of noninvasive techniques such as ultrasonics, eddy currents and acoustic emission.

The insatiable demand from designers for ever more advanced materials

combined with an increasing awareness of the poor posture of our basic

materials in the international marketplace has resulted in an unparalleled

interest in the development of a new generation of materials processing

sensors. The fortuitous juncture of expertise in nondestructive

characterization methods and advanced materials processing has created a unique window of opportunity for this group to make positive contributions

to one of the nations most important technological problems. The American

Iron and Steel Institute and National Bureau of Standards (AISI/NBS)

collaborative research program on sensors for the steel industry has

rapidly progressed. An ultrasonic sensor for detecting and locating

internal porosity/pipe in hot steel ingots has been developed in

cooperation with Magnaflux Corporation and successfully evaluated in

full-scale trials at the Argonne National Laboratory (ANL). Our

involvement in this activity is now completed. A second sensor for

determining internal temperature distributions has also progressed well,

and is now to the stage where a prototype is to be developed by

AlSl/Pacific Northwest Laboratory (PNL) and evaluated at a steel industry

casting facility. Our involvement in this effort is to continue, for we have devised an innovative approach that potentially could revolutionize

temperature measurement. There also remains a strong need for better

modeling of sensor-microstructure interactions and reference data to

support industrial uses of either sensor approach.

A new sensor program was initiated in May 1986 with the signing of a memorandum of Agreement with the Aluminum Association (AA) for cooperative

research and development of a temperature sensor for control of aluminum

alloy extrusion. For this sensor need, a multifrequency eddy approach has

been chosen as the preferred sensing method. It can potentially yield

surface and internal temperature information through the "skin depth

effect .

A new area in Metal Matrix Composite (MMC) interface characterization was initiated in FY 1985 and has now begun to yield important results. The

intent of the SDI/SDIO cofunded program is to develop methods for insitu

measurement of local mechanical properties at the ceramic-metal interface

in metal matrix composites. Theoretical studies have predicted, and

experiments have confirmed, the existence of guided interface waves at the

cylindrical interfaces of SiC-Al fibrous composites. These ultrasonic

59
experiments have confirmed, the existence of guided interface waves at the

cylindrical interfaces of SiC-Al fibrous composites. These ultrasonic

waves promise to reveal the local elastic constants of the interface

region. Acoustic emission studies, on the other hand, have begun to

reveal the micromechanisms of interface and fiber failure and allow

measurement of key quantities such as interface adhesive strength.

As the group's research programs mature, we are beginning to look to

future activities. For example, a steel industry workshop was convened at

NBS in July 1986 to identify sensor needs for detection of internal

discontinuities. The imminent arrival of Ward Johnson from the University

of Illinois provides us with the additional ultrasonic expertise to

explore the use of acoustic microscopy for characterization of the

microelastic state. Melvin Linzer has formulated an approach for imaging

the nonlinear elastic properties of media; a possible major contribution

to nondestructive measurement methods. The coming year may see one or more

of these areas become new subtasks in our group.

During FY 1986 collaborations and interactions with both industry and

academia have been extended. Cooperative research with the AISI and with

researchers from Johns Hopkins University (JHU) have continued. Four

overseas guest scientists, Yoram Berlinsky, Zvi Katz, Paul Horng, and Uri

Admon have made valuable contributions to our research program. New

interactions have commenced with the AA and MIT, the latter in which we

are playing a role in the SDI ' s Advanced Composites Consortium.

FY 86 Significant Accomplishments

o A prototype sensor, for detecting internal pipe/porosity in hot steel

bodies, has been successfully evaluated at ANL. NBS involvement in this

sensor activity has come to a successful conclusion.

o A high resolution computer based ultrasonic sensor for internal

temperature measurements in solidifying bodies has been constructed and

is undergoing evaluation.

o An eddy current approach to internal temperature measurement during the

extrusion of aluminum has been formulated and a prototype system

constructed for cylindrical geometries in cooperation with the AA.

o We have confirmed the existence of previously only suspected interface

waves at the cylindrical interfaces of fibrous SiC/Al metal matrix

composites. These waves show promise for characterizing the local

elastic state.

o Using specially prepared single crystal composite samples we have been

able to use acoustic emission techniques to observe fiber fracture and

interface decohesion during deformation of MMC's. This is enabling

determination of key quantities such as interface cohesive strength and

fiber fracture stress.

60
Eddy Current Temperature Profiling

Subtask 1

A. H. Kahn, M. L. Mester, and H. N. G. Wadley

The objective of this project is development of electromagnetic methods of

sensing temperature and temperature profiles of metals. The electrical

conductivity of a metallic material depends on temperature. If this

conductivity can be measured, it provides a method of obtaining the

temperature. If the conductivity profile can be determined, then so can

the profile of temperature, provided the conductivity-temperature

dependence of the alloy under test is already known. The depth of

penetration of ac magnetic fields and the associated eddy currents depend

on the frequency, and this allows the possibility of constructing the

profile of conductivity versus depth through the interpretation of

impedance measurements at varying frequencies.

During the past year, an agreement was reached with the AA, a consortium

of aluminum manufacturing and processing companies, to undertake a joint

project with NBS to develop sensors for the measurement of temperature and

temperature profiles in aluminum during extrusion processing. Michael L.

Mester, a consultant to the AA, has begun work on this project in

collaboration with NBS personnel through the NBS Research Associateship

Program. Visits were made to several processing plants to determine

process constraints upon physical designs for the proposed sensors.

To perform the impedance measurements necessary for research on conductivity profile determination and the design of sensors for field

use, we have acquired an impedance analyzer and set up a computer control

system which allows the rapid collection of measured data. Measurements

of impedance and phase at 400 frequencies are automatically performed in a matter of minutes and the results transferred to disk for analysis with

inversion programs for reconstructing the profiles. Programs have been

prepared for carrying out this process. The instrumentation is also being

used in testing designs for the water-cooled coils to be used in the

extrusion sensor.

An alternate approach to eddy current determination of temperature

profiles depends upon the measurement of conductivity and conductivity

gradient at the surface of the material under test. This determines the

temperature and temperature gradient at the surface of the material. With

this information it is possible to obtain solutions of the heat flow

equations and to obtain the temperature profile. This method depends on high frequency measurements which are readily obtained with the newly

acquired instrumentation. A theoretical approach has been developed for

obtaining the surface conductivity and the conductivity gradient at the

surface from multifrequency data. This approach is based on the Wentzel,

Kramers, Brillouin (WKB) method of approximate solution of wave equations

of nonuniform media in the limit of short wavelengths.

61
Pipe/Porosity Sensor

Subtask 2

M. Linzer and C. D. Rogers

An ultrasonic technique for detecting pipe and porosity in hot steel has

been successfully demonstrated. The method employs liquid glass (molten

Borax) to couple two buffer rods, in a pitch-catch arrangement, to the hot

steel surface. The other ends of the buffer rods are coupled to

piezoelectric transducers by conventional room temperature couplants.

Borax and stainless steel were shown to be the best liquid glass couplant

and buffer rod material among several tested. Subsequent evaluation at

the ANL of NBS technology has confirmed the choice of Borax as the optimum

couplant material. Based upon these accomplishments, this sensor is now

considered suitably developed for implementation in steel mills, and our direct involvement has come to a conclusion.

Ultrasonic Temperature Sensor

Subtask 3

F. A. Mauer, S. J. Norton, J. Cook, R. Heinrich, and H. N. G. Wadley

In 1982, a workshop sponsored jointly by NBS and AISI identified a need

for four types of sensors for use during automated process control in the

steel industry. One of these sensors was for the measurement of the

internal temperature distribution in hot steel bodies. During FY 86,

scientists from NBS and AISI continued their collaboration in order to

develop a method based on ultrasonic time-of-f light (TOF) tomography.

Theoretical and practical considerations governing formulation of the

temperature-profile reconstruction (tomography) problem were described in

Technical Activities-1985 , and temperature profile reconstructions based

on manual first-arrival TOF measurements were shown for hot solid bodies.

The reconstructed profiles agreed within 10_C with readings from embedded

thermocouples, which is adequate for most practical purposes.

During FY 86 attention has been directed toward automation of the

measurement and reconstruction procedure in order to increase the speed

and accuracy and to make it more suitable for use on solidifying bodies.

One of the steps taken to increase the speed of the automated system is

the replacement of a single, bulky EMAT receiver with two arrays, each

containing five piezoelectric receivers equipped with water cooled buffer

cones to isolate them from the hot steel block. This change permits us to

digitally record waveforms for all necessary propagation paths by simply

moving the beam steering mirrors under computer control. The new,

automated system is shown schematically in Figure 1. At first, mirror 1 is in the position shown and directs the laser beam along the axis of the

X positioner. The computer positions mirror 2 and fires the laser at

each of five points aligned with the five X receivers. Each time the

laser is fired, five transient recorders in a CAMAC crate record waveforms

from the five X receivers. Figure 2. Mirror 2 then moves far enough to

push mirror 1 out of the beam, allowing it to reach mirror 3. The

62
computer then scans the second face of the block by moving mirror 3 and

recording waveforms from the five Y receivers. In all, fifty waveforms

are recorded, from which the computer extracts TOF data and reconstructs a two-dimensional image. The 2-D temperature profile will be presented in a variety of formats (e.g., color coded, contour, and pseudo 3-D plots).

With the automated system we expect initially to be able to complete a scan in about fifteen seconds and to display a profile about fifteen

seconds later. A further order of magnitude improvement in speed is

anticipated. The rapid availability of a larger data set, free from

problems of temperature drift and ready for machine processing will permit

us to apply this promising new method to measurement of temperature and

the characterization of the solid/ liquid interface in solidifying bodies.

Temperature Profiling from Rayleigh-Wave Velocity Dispersion Measurements

Subtask 4

S. J. Norton, and H. N. G. Wadley

An investigation has begun into the feasibility of measuring the depthdependent temperature profile in the near surface of a body, or its

surface temperature gradient, from Rayleigh-wave velocity dispersion

measurements. For the case of an elastically-isotropic medium,

characterized by a depth-dependent density and two depth-dependent Lame

constants, an integral equation has been derived which relates the

dispersion measurements to the variations in these three material

parameters. Since changes in the material parameters are induced by

changes in temperature, the dispersion measurements can be used to compute

the temperature variation in the near surface region provided the

temperature dependence of the material parameters can be calibrated in

advance. The resulting integral equation is nonlinear since the

dispersion is also a function of the wave field as well as the material

parameters. Using first-order perturbation theory, the equation can be

linearized by substituting the unperturbed wave field into the integral

equation, providing a linear relation between the measurements (surface

wave dispersion) and the unknown (the temperature profile). If a finite

weighted sum of suitable basis functions is used to approximate the

one-dimensional temperature profile (e.g., piece-wise linear functions),

the integral equation can be evaluated analytically. Analytical

integration can also be performed if the unknown is the surface

temperature gradient only. The resulting integration yields a system of

linear equations which can be inverted to obtain a least-squares estimate

of the basis-function coefficients using standard linear inversion methods

(e.g., singular value decomposition).

Progress to date includes the derivation of the linearized integral

equation and its analytical evaluation for the case of a linear surface

gradient. Future work will include an evaluation of the integral equation

for the case of piece-wise linear basis functions, and a study of the

ill-conditioning of the resulting linear system of equations. This will

determine the maximum number of basis functions that can be feasibly

employed and, as a result, the best spatial resolution in the

63
reconstructed temperature profile that can be expected. Our interest in

this approach stems from its possibility of directly measuring the heat

transfer coefficient of a surface. With this information, thermal models

for casting and reheating are sufficiently powerful to predict accurately

the temperature everywhere within.

Acoustic Emission Study of Interface Adhesion in Metal Matrix Composites

Subtask 5

R. B. Clough, F. Biancaniello, and H. N. G. Wadley

The cohesive strength of composite interfaces (matrix-reinforcement

interface) in metal matrix composites is one of the least understood but

most important of variables, since it critically affects both strength and

fracture toughness. The principal reason for this lack of understanding

is an absence of experimental approaches for direct measurement of this

quantity. Such measurements provide a basis for understanding the

metallurgy of interfacial bonding and thus a way toward improving

mechanical properties.

When interfacial decohesion occurs, elastic waves are emitted. Thus,

detection of acoustic emission can be used to determine the load at

failure and the local fracture stress of the event. Transducers attached

at both ends of the sample monitor the arrival of fracture-initiated

stress waves, and by comparison of arrival times, the location of the

microfracture can be determined. The location can be determined by

comparison of signal waveforms using cross-correlation. Having identified

the site of the fracture, post- test metallography has been used to

identify the size and geometry of the fracture.

An advanced acoustic emission system has been constructed and interfaced

with a 32-bit minicomputer to permit continuous monitoring during tensile

testing of load, strain, and acoustic emission as well as automated

capture of the large acoustic emission transients associated with

microfracture. A unique feature of the system is the use of a highspeed

wideband rms-to-dc converter to calculate signal energy prior to capture

so that orders of magnitude fewer data points need to be stored.

Preliminary tensile tests of composites were made using the continuous

monitoring system. Load elongation curves of monofilament SiC in single

crystal aluminum show pronounced load drops which are simultaneously

accompanied by acoustic emission. Fig. 3a. Post-test metallography

reveals these fibers to be broken transversely in accordance with

composite fracture mechanics models. These fractures cause load drops and

associated bursts of emission. In addition, smaller acoustic signal which

do not produce load drops occur and are thought to be due to interfacial

decohesion. In addition there is a background of continuous emission

produced by general plasticity in the matrix. By deforming single

crystals of pure aluminum this plasticity generated emission has been

independently measured, Fig. 3b. The fiber fracture strength is 0.3GPa

(only 10% of that of a virgin fiber) while the interface shear strength is

9MPa consistent with failure by matrix slip.

64
Ultrasonic Techniques for Interface Characterization in Metal Matrix

Composites

Subtask 6

J. A. Simmons, E. Krasicka, M. Rosen, T. Hsieh, E. Lindgren, K. Hirshman

and H. N. G. Wadley

The performance of advanced metal matrix composites is critically

dependent upon the mechanical properties of the interface between the

metal matrix and the ceramic reinforcement. The interface can be

considered as a surface or as a region of coupling/transmitting

displacements and surface tractions between the reinforcing material and

the metal matrix. The goal of this subtask is to develop methods for

measuring the local elastic properties of the interface by utilizing

ultrasonic scattering and guided interface waves.

When ultrasonic waves encounter the discontinuity associated with an interface, they are both reflected and refracted. The character of these

scattered waves is dependent on the elastic properties of the interface.

In some cases a part of the energy travels as a wave in the direction of

the interface and is concentrated near the interface. We refer to such

waves as guided interface waves (GIW). The simplest example of a GIW is

the Stoneley wave which travels unattenuated and nondispersively between

two elastic half spaces when sufficiently restrictive conditions are

obeyed by the elastic constants of both regions. In other cases and other

geometries, such as the cylindrical geometry of a fiber reinforced

material, GIW's still exist, but the velocity is dispersive and energy

leaks away from the interface region as the wave travels, resulting in an attenuating or 'leaky' GIW. The velocities and leakage of such waves are even more sensitively dependent upon the interface mechanical properties

and extent of the interface than in the case of scattered waves.

Wave propagation theory has been worked out in the cylindrical geometry

for radially symmetric GIW's traveling in a medium consisting of an isotropic rod and an enclosing isotropic matrix. Leaky GIW's have been

theoretically predicted and experimentally measured in the model composite

case of silicon carbide reinforced aluminum. Figure 4. The wave was generated by sending a surface wave along a free SiC cylinder extending

out from the end of an aluminum encasement. The wave partially converts

to a leaky GIW upon entering the aluminum and is detected along the

cylinder at the other end of the encasement at a length along the

cylindrical axis of approximately eight rod diameters. Figure 5.

Measurement of the predicted attenuation is in progress. Detection of

leakage displacement profiles has been carried out in a stainless-steel

reinforced aluminum system using a sensitive water-bath measurement

apparatus, Figure 6. This type of experiment has not yet been correlated

with theory.

In the planar geometry, a propagator matrix theory has been developed for

scattering and GIW in an elastic A-B-C sandwich of materials on which the

B layer corresponds to the interface. For modeling we have tried to keep

this layer as general as possible. So far we consider it a homogeneous

65
thin anisotropic region with possible anelasticity (dislocation motion)

and viscoelasticity. The theory for both the cylindrical and planar

geometries can be further generalized to an inhomogeneous interface region

in which the composition and properties can vary from the matrix over to

the reinforcements. Because ultrasonic scattering is strongly dependent

upon inhomogeneities, this structural difference should be measurable at

high frequencies.

Experiments in the propagation of Stoneley waves in the planar geometry

have been carried out in conjunction with Moshe Rosen and graduate

students K. Hirshman and E. Lindgren from JHU.

Three major issues were considered:

1. The effect of surface smoothness.

2. The effect of microstructure near the interface.

3. The effect of wavelength on probing non-uniform structure on either

side of the interface.

It was found that the velocity of propagation of GIW at a titanium-steel

interface is strongly affected by the surface smoothness at the interface.

The two materials were subjected to pressure normal to the interface and

the GIW velocity measured as a function of pressure and surface

smoothness. For a fixed surface finish the velocity increased with

increasing pressure to that of the theoretically predicted Stoneley wave. Increasing the smoothness of the surface finish decreased the amount of

pressure needed to achieve the Stoneley velocity.

The microstructure of the materials forming a planar interface have been

found to have a substantial effect on the measured Stoneley wave

velocities of the titanium-steel couple. Microstructural variations could

be achieved by subjecting steel plates to controlled heat treatments to

yield microstructures of coarse pearlite, fine pearlite, martensite, and

tempered martensite. It was found that the maximal values of the Stoneley

wave velocities, for the different titanium-steel couples, were sensitive

not only to the general microstructure but to the particular heat

treatments of the steel. Measurements are underway to determine whether

this effect is due solely to the change in elastic constants of the steel

produced by the changes in microstructure.

The velocity of Stoneley interface waves is nondispersive, i.e., frequency

independent. However, the penetration depth of these waves has an approximate linear dependence on wavelength. Thus, the material layer

through which the Stoneley wave propagates, at the interface between two

planar samples, will depend on the frequency of the propagating wave and

changes in the elastic properties will affect the Stoneley velocity.

.

This property may enable one to nondestructively characterize not only the

interface itself but also the elastic properties and integrity of the

material adjoining the interface. Measurements are currently being

conducted over a l-15MHz frequency range to determine the feasibility of

this approach.

66
Laser

Fig. 1 Schematic diagram of the automated system for

recording time-of-fl ight data for reconstruction

of temperature profiles.

Ultrasonic Solidification Sensor

Fig. 2 Schematic diagram of the computer based ultrasonic

sensor for determining temperature distributions in

solidifying bodies.

67
Fig. 3(a) Stress-strain and acoustic emission strain

relations for a single crystal of aluminum

containing a 140ym diameter SiC fiber along the

tensile axis.

Fig. 3(b) Shows the corresponding data for a single crystal

containing no fiber. | 68

1

AE/Rms

Volts

AE/Rms

Volts
SIC/fiL

MATRIX:

VELOCITY

IN

MM/uSEC

6.40

5.60

4.80

4.00

3.20

2.40

0 .

Fig. 4 Comparison of theoretically predicted (curve)

and experimentally measured (points) dispersion

behavior of a guided interface wave propagating

along the cylindrical surface of SiC rod buried

in an aluminum matrix.

69

SIC/AL

MATRIX:

ATTEN

(DB/MMhMHZ)
s

Fig. 5 Schematic diagram on model composite sample.

A surface wave propagating to the right undergoes

mode conversion at the interface to a "leaky"

guided interface wave. Radiation of both

longitudinal (L) and shear (S) waves occurs as the GIW propagates.

Fig. 6 The variation of transducer voltage with distance

along the outer aluminum surface when a guided

interface wave is propagating along a cylindrical

steel rod - aluminum matrix interface. The curves

S and L correspond to "leaky" radiation detected

with shear and longitudinal transducers.

70
MAGNETIC PROPERTIES Lawrence H. Bennett

Pulsed potentiostatic deposition has been developed for the production

of composition modulated alloys (CMA) by the Electrodeposition Group.

A cooperative effort has been established between NBS and scientists

from the Naval Research Laboratory to study the magnetic properties of

electrodeposited CMA. Magnetization and ferromagnetic resonance

studies have now been completed in Cu-Ni and Cu-Co alloys. Transmission electron micrography shows the existence of sharp interfaces

and x-ray diffraction shows satellite lines. The magnetic results on the two alloy systems contrast strongly. In the Ni-Cu, the room

temperature magnetic moment reduced rapidly with layer thickness, for

Ni thicknesses less than about 6 nm. (This is the same behavior

reported for vapor-deposited Ni-Cu CMA.) No such systematic trends

were seen in the Co-Cu. We conclude that the reduced moment of Ni in

Ni-Cu multilayered structures may be the result of greater

interdiffusion of Ni into Cu, as compared to Co into Cu.

We are continuing the study of the local topology of atoms in crystals,

in collaboration with Dr. R. E. Watson of Brookhaven National

Laboratory. The method used is a Wigner-Seitz (or Voronoi) analysis,

with provision for accounting for the different radii of the atoms. We

have proposed a connection between the occurrence of strong magnetism

and "disclination" paths inferred from our computations. These ideas

are being applied to suggestions for new hard magnetic materials, and

to aid in the analysis of site occupancies in magnetic materials.

We have carried out nuclear magnetic resonance experiments in the

aperiodic Al-Mn Shechtmanite crystals, as well as in normal Al-Mn

crystalline structures. We conclude that there is a broad distribution

of A1 and of Mn site environments in Shechtmanite, and that the

electronic and magnetic structure of the Shechtmanite is similar to the

periodic crystals. We have also used the Wigner-Seitz analysis to

investigate site symmetries and local environments in two different

descriptions of Shechtmanite.

In collaboration with colleagues at the Naval Surface Weapons

Laboratory and a visiting Israeli, Dr. M. Melamud, we have used the

Mossbauer effect to measure the distribution of magnetization in

metallic glasses having large magnetomechanical couplings.

We have measured the temperature dependence of the ac susceptibility

for melt-spun monel (see Figure). The tail above the steep drop

("Hopkinson effect") from 320 to 355K in the melt-spun alloy is due to

a distribution of Curie temperatures which may arise from microscopic

compositional in homogeneity. The fine granular structure obtained in

the rapid solidification process reduces the effective magnetocrystalline anisotropy as evidenced by the enhanced low temperature ac susceptibility.

71
Su

s

c

F'-J 1 dH U_-4 h—1 S ^|C2J I I t—

I

Figure 1. The ac susceptibility of a melt-spun ribbon of a Ni-Cu alloy of

the monel composition. The microstructure is columnar, with a grain width

of about pm.

72
PUBLICATIONS

Structure Characterization Group

Black, D. R.; Bechtoldt, C. J.; Placious, R. C.; Kuriyama, M.;

Three-dimensional strain measurements with X-ray energy dispersive

spectroscopy. J. of Nondestructive Evaluation 5 (1); 21-25; 1985.

Black, D. R.; Burdette, H. E.; Early, J. G.; Diffusion bonding of

ductile single crystals for strain free mounting. J. of Appl.

Crystallography 19; 1986.

Black, D. R. ; Spain, I. L.; Energy dispersive X-ray diffraction in the

diamond anvil high pressure apparatus: Comparison of synchrotron and

conventional X-ray sources. Rev. Sci. Inst. 56 (7); 1461-1463; 1985.

Dobbyn, R. C.; Boettinger, W. J.; Voorhees, P. W.; Burdette, H. E.; A

study of the coarsening of liquid-solid mixtures using synchrotron

radiation microradiography. Met. Trans. A; 1986; in press.

Dobbyn, R. C.; Glinka, C. I.; Fields, R. J.; Microstructural

characterization by small angle neutron scattering. NDE of

Microstructure for Process Control. ASM; Metals Park, OH; 1985.

Kuriyama, M.; Long, G. G.; Single crystal structure of rapidly cooled

alloys with icosahedral symmetry: II Theoretical analysis --Internal

modulations. Acta Cryst. A 42; 164-172; 1986.

Kuriyama, M. ; Long, G. G.; Bendersky, L.; Unit-cell structure of

rapidly cooled Al-Mn alloys with icosahedral symmetry. Phy. Rev. Lett.

55; 849-851; 1985.

Long, G. G. ; Kruger, J.; EXAFS as a technique for studying the effects

of alloying elements on the nature of the oxide films on steels proc.

USA- Japan Seminar; Critical Issues in Reducing the Corrosion of Steels,

Nikko, Japan, NACE; 1985; in press.

Long, G. G. ; Kuriyama, M. ; Single crystal structure of rapidly cooled

alloys with icosahedral symmetry: I Experimental analysis. Acta

Cryst. A 42; 156-164; 1986.

Long, G. G.; Kuriyama, M.; Theory of extinction in dynamical X-ray

diffraction by real crystals. Acta Cryst. A; in press.

Long, G. G.; Revesz, A. G.; Kuriyama, M.; X-ray absorption study of

tantalum oxide films on silicon. J. Noncrystalline Solids 70; 271-278;

1985.

Spal, R.; Interpenetrating incommensurately modulated lattices with

icosahedral symmetry. Phy. Rev. Lett. 56: 1823; 1986.

73
Metallurgical Processing Group

Bendersky, L. ; Decagonal phase. Proc. of Workshop on Aperiodic

Crystals; Les Houches; 1986; in press.

Bendersky, L. ; Quasicrystals with 1-D translational periodicity and a ten-fold rotation axis. MRS Proceedings; Boston; 1986; in press.

Bendersky, L. A.; Biancaniello, F. S.; Boettinger, W. J.;

Perepezko, J. H. ; Microstructure of rapidly solidified Nb-Si alloys.

Mats. Sci. and Eng.; 1986; in press.

Bendersky, L.; Kaufman, M. J.; Determination of the point group of the

icosahedral phase in an Al-Mn-Si alloy using convergent beam electron

diffraction. Phil. Mag. B 53; 3; L15; 1986.

Bendersky, L. A.; Ridder, S. D.; Nucleation behavior of Al-Mn

icosahedral phase. J. Mats. Res. 1; 3; 405; 1986.

Bendersky, L. ; Schaefer, R. J.; Biancaniello, F. S.; Boettinger, W. J.;

Kaufman, M. J.; Shechtman, D.; Icosahedral Al-Mn and related phases:

Resemblance in structure. Scripta Met. 19; 909; 1985.

Bendersky, L.; Schaefer, R. J.; Biancaniello, F. S.; Shechtman, D.;

Rapidly solidified Al-Cr alloys: structure and decomposition behavior.

J. of Mats. Sci. 21; 1889; 1986.

Blendell, J. E,; Handwerker, C. A.; Effect of chemical composition on sintering of ceramics. J. Cryst. Growth 75 (1); 138; 1986.

Boettinger, W. J.; Bendersky, L. A.; Early, J. G.; An analysis of the

microstructure of Al-8 wt% Fe rapidly solidified powders. Met. Trans. A

17A; 781; 1986.

Boettinger, W. J.; Coriell, S. R.; Microstructure formation in rapidly

solidified alloys. Proc. of NATO Advanced Research Workshop on Rapid

Solidification Technologies; 1985; in press.

Boettinger, W. J.; Perepezko, J. H.; Fundamentals of rapid

solidification. Rapidly Solidified Crystalline Alloys; S. K. Das,

B. H. Kear, and C. M. Adam, eds.; TMS-AIME; 21; 1985.

Glicksman, M. E.; Coriell, S. R. ; McFadden, G. B.; Interaction of flows

with the crystal-melt interface. Ann. Rev. Fluid Mech. 18; 307; 1986.

Hackney, S. A.; Biancaniello, F. S.; Directional invariance of grain

boundary migration in the Pb-Sn cellular transformation and the

Tu-Turnbull hysteresis. Scripta Met.; 1986; in press.

Hackney, S. A.; Biancaniello, F. S.; Yoon, D. N.; Handwerker, C. A.;

Observations on crystal defects associated with diffusion induced grain

boundary migration in Cu-Zn. Scripta Met. 20; 937; 1986.

74
Hackney, S. A.; Shiflet, G. J.; Anisotropic interfacial energy at

pearlite lamellar boundaries in a high purity Fe-0.80% C alloy.

Scripta Met. 20; 389; 1986.

Handwerker, C. A.; Diffusion induced grain boundary migration in thin

films. Diffusion in Thin Films; D. Gupta and P. Ho, eds. Noyes

Publications; 1986; in press.

Hardy, S. C.; The surface tension of liquid gallium. J. Cryst. Growth

71; 602; 1985.

Low, S. R.; Early, J. G. ; Drop-weight testing of non-standard specimen

geometries. ASTM Spec. Tech. Pub. 919; 1986.

McFadden, G. B.; Coriell, S. R.; The effect of fluid flow due to the

crystal-melt density change on the growth of a parobolic isothermal

dendrite. J. Cryst. Growth 74; 507; 1986.

McFadden, G. B.; Coriell, S. R. ; Boisvert, R. F.; Double-diffusive

convection with sidewalls. Phys. Fluids 28 (9); 2716; 1985.

Parker, R. L. ; Manning, J. R.; Application of pulse-echo ultrasonics to

locate the solid/ liquid interface during solidification and melting.

Proc. of 8th International Conference on Crystal Growth; North-Holland

Publishing; Amsterdam; 1986.

Parker, R. L.; Manning, J. R.; Peterson, N. C.; Application of

pulse-echo ultrasonics to locate the solid/ liquid interface during

solidification and melting of steel and other metals. J. Appl. Phys.

58; 4150; 1985.

Perepezko, J. H. ; Boettinger, W. J.; Kinetics of resolidification.

Surface alloying by ion electron and laser beams. ASM; in press.

Rottman, C.; Thermal fluctuations in interfaces: From fluid-fluid

interfaces to small-angle grain boundaries. Conference volume for

International Conference on Low-Energy Dislocation Structures.

Mats. Sci. and Eng. 81; 553; 1986.

Rottman, C.; Thermal fluctuations in low-angle grain boundaries, Acta

Met.; 1986; in press.

Schaefer, R. J.; The metallurgy of quasicrystals. Scripta Met.; 1986;

in press.

Schaefer, R. J.; Bendersky, L. ; Formation of quasicrystals in rapidly

solidified A1 alloys. Materials Research Society Symposium Series;

1986; in press.

Schaefer, R. J.; Bendersky, L. ; Replacement of icosahedral Al-Mn by

T phase. Scripta Met. 20; 745; 1986.

75
Schaefer, R. J.; Bendersky, L.; Biancaniello, F. S.; Nucleation and

growth of aperiodic crystals in aluminum alloys. Proc. of International

Workshop on Aperiodic Crystals. Journal de Physique; 1986; in press.

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; in press.

Schaefer, R. J.; Biancaniello, F. S.; Cahn, J. W.; Formation and

stability range of G phase in the Al-Mn System. Scripta Met.; in press.

Voorhees, P. W.; Glicksman, M. E.; Thermal measurement of Ostwald

ripening kinetics in partially crystallized mixtures. J. Cryst. Growth

72; 599; 1985.

Voorhees, P. W. ; Johnson, W. C.; Interfacial equilibrium during a first

order phase transformation in solids. J. Chem. Phys. 84; 5108; 1986.

Voorhees, P. W,; Johnson, W. C.; Laraia, V. J.; Elastic effects during

late stage phase transformations. Solute-Defect Interaction; Theory

and Experiment. Pergamon Press; 409; 1985.

Voorhees, P. W.; Schaefer, R. J.; In situ observation of particle

motion and diffusional interactions during coarsening. Acta Met.; 1986;

in press.

Yoon, D. N.; Cahn, J. W.; Handwerker, C. A.; Blendell, J. E.;

Baik, Y. J.; Coherency strain induced migration of liquid films through

solids; in Interface Migration and Control of Microstructure. ASM

Press; 1986.

Wear and Mechanical Properties Group

Blau, P. J.; A model for run-in and other transitions in sliding

friction. J. of Tribology; 1986; accepted for publication.

Blau, P. J.; Applications of microindentation methods in tribology

research. ASTM STP 889, P. J. Blau and B. R. Lawn, eds; Philadelphia,

PA; 209; 1986.

Blau, P. J.; Measurements and interpretations of sliding wear damage in

metals. J. of Tribology 107; 483; 1985.

Blau, P. J.; Methods and applications of microindentation hardness

testing. Chapter in Handbook of Applied Metallography, G. Vander Voort,

ed.; Van Nostrand Co.; NY; 1986; in press.

Blau, P. J.; Microindentation hardness testing of coatings. Chapter in

Proc. Amer. Vac. Society Symposium on Physics and Chemistry of

Protective Coatings; 1985; in press.

76
Blau, P. J.; Wear testing methods and standardization. ASTM

Standardization News; 34; 1985.

Blau, P. J.; Lawn, B. R. , eds.; Microindentation techniques in

materials science and engineering. ASTM Spec. Tech. Pub. 889;

Philadelphia, PA; 1986.

Fraker, A. C.; Corrosion of ammunition. Proc. of 34th Dept, of Defense

Conference on Nondestructive Testing; S. 0. McMillan, ed.; Charleston,

SC; in press.

Kanakia, M. D. ; Owens, E. C.; Peterson, M. B.; High temperature

lubrication systems for ring/ liner applications in advanced heat

engines. Report to Department of Energy, A1641955; 1986.

Polvani, R. S.; Effects of vacancy silicon clusters on the creep of

NiAl. J. Mat. Sci.; 1986; in press.

Polvani, R. S.; Ruff, A. W.; Whitenton, E. P.; A dynamic

microindentation apparatus for materials characterization. ASTM J.

Testing and Evaluation; 1986; in press.

Rigney, D. A.; Naylor, M. G. S.; Divakar, R.; Ives, L. K.; Low energy

dislocation structures caused by sliding and particle impact. Proc. of

International Conference on Low-Energy Dislocation Structures,

University of Virginia; Charlottesville, VA; August 1986.

Ruff, A. W.; Analysis of inter laboratory test results of solid particle

impingement erosion. Wear; 108; 323; 1986.

Ruff, A. W.; Ludema, K. C.; Wear. Encycl. of Mat. Sci. and Eng.;

M. B. Bever, ed. Pergamon Press; 5273; 1986.

Ruff, A. W.; Polvani, R. S.; Characterization of surface properties of

materials including wear. Proc. of the SURTEC International Conference

on Surface Technology; Berlin, West Germany; October 1985.

Ruff, A. W.; Schmitt, G. F.; Erosion. Encycl. of Mat. Sci. and Eng.;

M. B. Bever, ed. Pergamon Press; 1573; 1986.

Chemical Metallurgy Group

Massalski, T. B.; Murray, J. L. ; Burton, B. P.; Bennett, L. H.,

tech, eds.; Constitution of binary alloys. Bull. Alloy Phase Diagrams;

in press.

McAlister, A. J.; Kahan, D. J.; The Al-Pt ( aluminium-plat ium) system.

Bull. Alloy Phase Diagrams 7(1); 47; 1986.

McAlister, A. J.; Murray, J. L. ; The Al-Mn (aluminium-manganese)

system. Alloy Phase Diagrams; in press.

77
Murray, J. L.; Assesment and calculation of the Ti-Cu phase diagram.

Noble Metal Alloys; T. B. Massalski, et al., eds. Proc. of TMS Alloy

Phase Committee at the Metallurgical Society AIME Annual Meeting;

February 1985; 289-304.

Murray, J. L.; Constitution of binary titanium alloys. American

Society for Metals; in press.

Murray, J. L.; The Al-Cu (aluminium- copper) system. Int. Met. Rev.

30(5); 211-233; 1985.

Murray, J. L.; The Ga-Ti (gallium-titanium) system. Bull. Alloy Phase

Diagrams 6(4); 327-330; 1985.

Murray, J. L.; The Pb-Ti (lead-titanium) system. Bull. Alloy Phase

Diagrams 5(6); 613-615; 1985.

Murray, J. L. ; The Se-Ti (selenium- titanium) system. Bull. Alloy Phase

Diagrams 7(2); 1986; in press.

Murray, J. L.; The S-Ti ( sulf er-titanium) system. Bull. Alloy Phase

Diagrams 7(2); 1986; in press.

Nash, P.; Murray, J. L.; The Al-Ni (aluminium-nickel) system. Bull.

Alloy Phase Diagrams; in press.

Schechtman, D.; Swartzendruber , L. J,; Metastable phases in rapidly

solidified Al-rich Al-Fe alloys. Transactions; AIME; 1986.

Spear, K.; Murray, J. L.; The B-Ti (boron-titanium) system. Bull.

Alloy Phase Diagrams 7(2); 1986; in press.

Swartzendruber, L. J.; The Fe-Cr ( iron-chronium) System. Bull. Alloy

Phase Diagrams; 1986.

Swartzendruber, L. J.; The Fe-Cu (iron-copper) System. Bull. Alloy

Phase Diagrams; 1986.

Swartzendruber, L. J.; Alcock, C. B.; Itkin, V. P.; The Fe-Ni

(iron-nickel) system. Bull. Alloy Phase Diagrams; 1986.

Swartzendruber, L. J.; Bennett, L. H.; Nuclear magnetic resonance. Metals Handbook, Vol. 3. ASM; 277; 1986.

Swartzendruber, L. J.; Massalski, T. B.; Pearson, W. B.; Bennett, L. H.;

Chang, Y. A.; Thermodynamic assessment of the iron noble-metal

equilibrium diagrams. AIME; 1986; 305.

Corrosion Group

Bertocci, U.; Electrochemical principles of corrosion. Encycl. of Mat.

Sci. and Eng. Pergamon Press; 1403; 1986.

78
Bertocci, U. ; Random noise in passivity. 5th Brasilian Symposium of

Electrochemistry; 1986; in press.

Bertocci, U. ; Pugh, E. N. ; Modeling of the potential at the tip of a transgranular stress-corrosion crack in the alpha-brass-ammonia system.

Proc. of Conference on Corrosion Chemistry Within Pits, Crevices, and

Cracks; London; 1984; in press.

Escalante, E. ; Patterson, D. E.; Husar, R. B.; Bronze, zinc, aluminum

and galvanized steel: corrosion rates as a funciton of space and time

over the United States. ACS Symposium Series 318, Materials Degradation

Caused by Acid Rain; 152; 1986.

Escalante, E. ; Underground corrosion. Encycl. of Mat. Sci. and Eng.

Pergamon Press; 1986.

Interrante, C. G. ; Standard terminology related to fracture testing.

ASTM designation E616-82 2, revised in April 1986; ASTM 03.01; Annual

Book of ASTM Standards; 1986.

Kaufman, M. J.; Cunningham, J. E. ; Fraser, H. L.; Metastable phase

production and transformation in Al-Ge alloy films by rapid

crystallization and annealing treatments. Acta Met.; in press.

Kaufman, M. J.; Ellner, M. ; Fraser, H. L. ; Constitution of an Al-37.5 Ge splat quenched foil: Implication on nucleation kinetics.

Scripta Met. 20; 103; 1986.

Kaufman, M. J.; Forty, A. J. ; A detailed fractographic analysis of

cleavage steps in Si. J. Mat. Sci.; in press.

Kaufman, M. J.; Fraser, H. L. ; Undercooling and microstructural

evolution in glass forming alloys. Proc. of the Hume-Rothery Symposium

on Undercooling; C. C. Koch, E. W. Collings, eds.; in press.

Kaufman, M. J.; Konitzer, D. G. ; Shull, R. D.; Fraser, H. L. ; An

analytical electron-microscopy study of the recently reported T^Al

phase in -TiAl alloys. Scripta Met. 20; 125; 1986.

Kaufman, M. J.; Pearson, D. D.; Fraser, H. L.; The use of convergent

beam electron diffraction to determine local lattice distortions in

Ni-base superalloys. Phil. Mag.; in press.

Kaufman, M. J.; Pugh, E. N. ; Thomson, R. M. ; Forty, A. J.; A mechanism

for cleavage crack arrest by ligament formation in transgranular stress

corrosion cracking. Scripta Met.; in press.

Kaufman, M. J.; Shull, R. D. ; Nature of large Ti^Cu20 particles formed

during annealing of CuccTiAc metallic glass ribbons. Metall. Trans.

17A; 575; 1986.

Pugh, E. N. ; Corrosion: Metallurgical aspects. Encycl. of Mat. Sci.

and Eng. Pergamon Press; 889; 1986.

79
Pugh, E. N. ; Corrosion cracking. Encycl. of Mat. Sci. and Eng.

Pergamon Press; 4669; 1986.

Pugh, E. N.; Kaufman, M. J. ; Cleavage step formation and resistance to

transgranular stress corrosion cracking. Proc. 1986 Materials

Technology Congress; Adelaide, Australia; May 1986; in press.

Ricker, R. E. ; Baumert, B.A.

;

Effect of heat treatment on corrosion

resistance of Al-Li alloys. Aluminum Lithium Alloys III; C. Baker; P. J. Gregson; S. J. Harris; C. J. Peel, eds. The Institute of Metals;

London, England; 282-286; 1986.

Ricker, R. E. , contributor to book; Failure analysis and prevention.

Metals Handbook, Vol. 11, 9th Ed. ASM; Metals Park, OH; 1986.

Ricker, R. E. , contributor to book; Fractography and atlas of

f ractographs . Metals Handbook, Vol. 10, 9th Ed. ASM; Metals Park, OH;

1986.

Ricker, R. E.; The influence of environment on the fatigue properties

of Aluminum alloys. Modeling Environmetally Effects on Crack Initiation

and Propagation; R. Jones, ed. American Institute of Mining,

Metallurgical and Petroleum Engineers; New York; 1986.

Ugiansky, G. M. ; Clausen, D. C.; The NACE-NBS corrosion data program:

An answer to the high cost of corrosion. Proc. of Corrosion Prevention

and Control Conference "Major Initiatives in Corrosion Prevention and

Control" sponsored by U.S. Army Material Command; Williamsburg, VA;

April 1986.

Ugiansky, G. M. ; Payer, J. H. ; Impact of the NBS-Battelle cost of

corrosion study of the USA. Proc. of Corrosion '86 Symposium on International Approaches to Reducing Corrosion Costs sponsored by NACE;

Houston, TX; March 1986.

Ugiansky, G. M. ; Van Orden, A. C.; Clausen, D. C.; The NACE-NBS

corrosion data program. The International Corrosion Forum:

Corrosion '86, sponsored by NACE; Houston, TX; March 1986.

Electrodeposition Group

Lashmore, D. S.; Brown, H. J.; Kelley, D. R. ; The production of a duplex nickel standard reference material. J. Plating and Surface

Finishing 73; 10; 1986.

Lashmore, D. S.; Oberle, R.; Dariel, M. P.; Electrodeposition of

artificially layered material. Proc. of 1986 International Pulse

Plating Symposium; Washington, DC.

Lashmore, D. S.; Weisshaus, I.; Pratt, K. W. ; Electrodeposition of

nickel-chromium alloys. J. Plating and Surface Finishings 73(3); 48;

1986.

80
Ratzker, M. ; Lashmore, D. S.; Pratt, K. W. ; The corrosion performance

of electrodeposited nickel-phosphorus amorphous alloys. J. Plating and

Surface Finishing 9; 73; 1986.

VanVechten, T. C.; Lashmore, D. S.; Johnson, C. E. ; Puippe, J. C.;

Electrochemical measurement of surface area. J. Plating and Surface

Finishing 73; 9; 1986.

Nondestructive Characterization Group

Alers, G. ; Wadley, H. N. G. ; Development of easily scanned transducers

for the ultrasonic testing of hot steel. Proc. of Review of

Quantitative NDE; San Diego; August 1986.

Berlinsky, Y. ; Rosen, H. ; Simmons, J. A.; Wadley, H. N. G. ; A

calibration approach to acoustic emission energy measurement. NDE

Communications; 1986.

Berlinsky, Y. ; Rosen, M. ; Simmons, J. A.; Wadley, H. N. G. ; Acoustic

emission: A technique for characterizing the martensitic transformation

in Fe-30 wt%Ni. Proc. of Review of Quantitative NDE; Williamsburg, VA;

June 1985.

Berlinsky, Y. ; Rosen, M. ; Simmons, J. A.; Wadley, H. N. G. ; Acoustic

emission: An NDE technique for characterizing the martensitic

transformation. Review of Progress of Quantitative NDE 5;

D. 0. Thompson and D. E. Chimenti, eds; Plenum Press; 1986.

Clough, R. B.; Schaefer, R. ; Wadley, H. N. G.; Acoustic emission

monitoring of laser drilling in NDE of microstructure for process

control; H. N. G. Wadley, ed. ASM; Metals Park, OH; 1985; 133-142.

Droney, B. E.; Wadley, H. N. G.; Norton, S. J. ; Mauer, F. A.;

Experiments with ultrasonic sensors to measure internal temperature

distributions. Proc. of Review of Quantitative NDE; Williamsburg, VA;

June 1985.

Elkind, B. J. ; Rosen, M. ; Wadley, H. N. G. ; Ultrasonic characterization

of surface modified layers. Met. Trans. A; 1986; in press.

Elkind, B. J. ; Rosen, M. ; Wadley, H. N. G.; Ultrasonic characterization

of microstructurally modified surfaces of steel subjected to electron

beam irradiation. World Conference on NDT 3; 1985; Las Vegas, NV;

1633-1640.

Gvishi, M. ; Rosen, M. ; Wadley, H. N. G. ; Nondestructive

characterization of the martensitic phase transformation in NiTi by

means of acoustic emission and electrical resistivity. Review of the

Progress in Quantitative NDE 4B; D. Thompson and D. Chimenti, eds.

Plenum Press; 1985.

81
Kahn, A. H. ; Long, K. R. ; Ryckebusch, S.; Hsieh, T.j Testardi, L. R.

;

Determination of electrical conductivity profiles from frequency-sweep

eddy current measurement. Review of Progress in Quantitative NDE 5;

1383; 1986.

Kahn, A. H. ; Wadley, H. N. G.; Application of eddy current methods to

the in-process measurement of temperature distributions. Proc. of the

Aluminum Association Workshop on Sensors; Atlanta, GA; May 1986; in

press

.

Krasicka, E. D. ; Simmons, J. A.; Wadley, H. N. G.; Guided interface

waves. Proc. of Review of Quantitative NDE; San Diego, CA; August 1986.

Linzer, M. ; Sato, T. ; Ikeda, 0.; Hatsuzawa, T.; Real-time evaluation of

wear particles using electro-magnetic forced rotation and laser

scattering. Wear; in press.

Mauer, F. A.; Droney, B. E. ; Norton, S. J.; Wadley, H. N. G.;

Ultrasonic sensors to measure internal temperature distribution. Review

of Progress in Quantitative NDE; D. 0. Thompson and D. E. Chimenti,

eds.; 5A; 643-650; Plenum Press; 1986.

Norton, S. J.; Testardi, L. R. ; Reconstruction of one-dimensional

inhomogeneities in elastic modulus and density using acoustic

dimensional resonances. J. Acoust. Soc. Amer. 79; 932-941; 1986.

Rosen, M. ; Ives, L.; Ridder, S.; Biancaniello, F.; Mehrabian, R.

;

Correlation between ultrasonic and hardness measurements in aged

aluminum alloy 2024. Materials Science and Engineering 74; 1; 1985.

Simmons, J. A.; Deconvolution for acoustic emission. Review of

Progress in Quantitative NDE; D. 0. Thompson, ed.; 5; Plenum Press;

1986.

Smith, J. J.; Rosen, M. ; Wadley, H. N. G.; Laser/ultrasonic NDE of melt

spun ribbons. World Conference on NDT; 2; Las Vegas, NV; 902-909.

Testardi, L. R. ; Norton, S. J.; Hsieh, T.; Acoustical dimensional

resonance tomography: Some examples in one-dimensional systems. J.

Appl. Phys. 59; 55-58; 1986.

Wadley, H. N. G.; Acoustic emission: A quantitative NDE technique for

the study of fracture. Solid Mechanics Research for Quantitative NDE;

J. 0. Achenbach and Y. Rajapakse, eds.; 1986.

Wadley, H. N. G.; Acoustic emission: Nature's ultrasound. Proc. of

Review of Quantitative NDE; Williamsburg, VA; June 1985.

Wadley, H. N. G. ; New sensors will save steel industry $400 million.

CME; February 1985.

82
Wadley, H. N. G. ; Process control sensors: Status of AISI

collaborative programs. Proc. of Vacuum Metallurgy Conference on Specialty Melting and Processing; Pittsburgh, PA; June 1986.

Wadley, H. N. G.; Norton, S. J. ; Mauer, F. A.; Droney, B. E.; An

ultrasonic method for measuring internal temperature distributions in

steel and aluminum. Proc. of the Aluminum Association Workshop on Sensors; Washington, DC; 1986; in press.

Wadley, H. N. G. ; Norton, S. J.; Mauer, F. A.; Droney, B. ; Ultrasonic

measurement of internal temperature distribution. Proc. of the Royal

Society of London; 1986; in press.

Wadley, H. N. G.; Norton, S. J. ; Droney, B. E. ; An ultrasonic method

for measuring internal temperature distribution in steel and aluminum.

Proc. of the Aluminum Association Workshop on Sensors; Washington, DC;

May 1986.

Magnetic Properties

Bennett, L. H. , ed.; Computer modeling of phase diagrams. Met. Soc. of

AIME; Warrendale, PA; 1986.

Bennett, L- H. ; McAlister, A. J.; Vegard's law. Encycl. of Mat. Sci.

and Eng. Pergamon Press; 5241; 1986.

Bennett, L. H. ; Mossbauer techniques in nondestructive evaluation.

Encycl. of Mat. Sci. and Eng.; 3121; 1986.

Bennett, L. H. , ed.; Resonance techniques. Metals Handbook, Vol. 10.

ASM; Metals Park, OH; 1986.

Bennett, L. H. ; Long, G. C.; Kuriyama, M.; Goldman, A. I.; Local atomic

structure in transition metal/metalloid glasses: Ni-P. Structure and

Bonding in Noncrystalline Solids; G. E. Walrafen, ed.; Plenum Press; in

press

Bennett, L. H. ; Swartzendruber , L. J.; Nuclear magnetic resonance.

Metals Handbook, Vol. 10 (Materials Characterization), 9th Ed.; 277;

ASM; Metals Park, OH; 1986.

Bennett, L. H. ; Watson, R. E. ; Systematics of the alloying behavior of

the noble metals. Noble Metal Alloys; T. B. Massalski, W. B. Pearson,

L. H. Bennett, and Y. A. Chang, eds . Met. Soc. of AIME; Warrendale, PA;

1986.

Bennett, L. H. ; Watson, R. E. ; Pearson, W. B.; Topology of local atomic

environments: Implications for magnetism and superconductivity. J.

Mag. and Mag. Mat. 54; 1537; 1986.

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 . ; in press.

83
Massalski, T. B. ; Pearson, W. B. ; Bennett, L. H. ; Chang, Y. A., eds.;

Noble metal alloys. Met. Soc. of AIME; 3; Warrendale, PA; 1986.

Melamud, M.; Bennett, L. H. ; Cullen, J.; Wun-Fogel, M. ; Moment

distribution in amorphous magnetic ribbons. J. Appl. Phys.; in press.

Melamud, M.; Bennett, L. H. ; Watson, R. E.; Where are the iron atoms

and iron moments in RFe^Al.,. n 12-n.0; A Wxgner-Seitz analysis. , J.TinAppl.

Phys.; in press.

Rubinstein, M. ; Bennett, L. H. ; Chien, C. L. ; Magnetism and the

observation of NMR lines in hexagonal Al^Mn and icosahedral Al-Mn

alloys. J. Appl. Phys.; in press.

Rubinstein, M. ; Stauss, G. H. ; Phillips, T. E. ; Moorjani, K.

;

Bennett, L. H. ; Nuclear magnetic resonance in Al-rich quasiperiodic

crystals. J. Mater. Res. 1; 243; 1986.

Swartzendruber , L. J.; Bennett, L. H. ; Mossbauer spectroscopy. Metals

Handbook, Vol. 10 (Materials Characterization), 9th Ed.; 287; ASM,

Metals Park, OH; 1986.

Swartzendruber, L. J.; Bennett, L. H. ; Ettedgui, H. ; Initial

susceptibility studies of rapidly solidified monel. J. Appl. Phys.; in

press.

Watson, R. E. ; Bennett, L. H. ; Alpha manganese and the Frank-Kasper

phases. Scripta Met. 19; 535; 1985.

Watson, R. E.; Bennett, L. H. ; The noble metals as incipient transition

elements. Noble Metal Alloys; T. B. Massalski, W. B. Pearson,

L. H. Bennett, and Y. A. Chang, eds. Met. Soc. of AIME; 3; Warrendale,

PA; 1986.

Watson, R. E. ; Bennett, L. H. ; The quasicrystalline structures of

transition metal/metalloid glasses. J. Mag. and Mag. Mat. 54- 57 ; 295;

1986.

Watson, R. E.; Bennett, L. H. ; Davenport, J. W. ; Weinert, M. ; Electron

band theory and the construction of phase diagrams. Computer Modeling

of Phase Diagrams, L. H. Bennett, ed. Met. Soc. of AIME; 1; Warrendale,

PA; 1986.

Watson, R. E. ; Melamud, M. ; Bennett, L. H. ; Disclinations and magnetism

in rare earth- transition metal hard magnets. J. Appl. Phys.; in press.

84
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 1986, the Division performed collaborative research with many private

organizations through its Industrial Research and Guest Worker programs

and other arrangements. Representative examples of such interactions

include:

INDUSTRY

1. Aluminum Association

A memorandum of understanding and agreement was signed with the

Aluminum Association in May 1986. The agreement is for the

cooperative research and development of a sensor for determining the

internal temperature of aluminum alloys undergoing high-speed

extrusion. Under the agreement Aluminum Association Research

Associate M. Mester is collaborating with NBS scientists in the

Nondestructive Characterization Group in evaluating novel

multifrequency eddy current approaches to internal temperature

measurement

2. American Iron and Steel Institute

The American Iron and Steel Institute (AISI) is sponsoring a program

in the Corrosion Group directed at identifying the effect of landfill

conditions on the corrosion of steel piling underground.

3. American Iron and Steel Institute

The Nondestructive Characterization Group has continued a strong

collaboration with the American Iron and Steel Institute (AISI) during

FY 86. 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. Research continues with

the temperature sensor toward developing full specifications for a prototype sensor.

85
4. 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. L. Murray and B. Burton (both of NBS). Three category editors of

the program are working at NBS: J. L. Murray, L. J. Swartzendruber

and A. J. McAlister, for Ti~, A1-, and Fe- alloys, respectively.

5. Artech Corporation

Henry Hahn, President of Artech Corporation, has worked with the Wear

and Mechanical Properties Group (A. C. Fraker) in conducting studies

of arc plasma sprayed porous coatings of titanium and Ti-6A1-4V. The

strength of the interface, corrosion fatigue behavior and corrosion

resistance were determined. Effects of variable parameters in the

porous coating application were investigated and best processing

methods were determined.

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. W. Glaeser of Battelle and A. W. Ruff (NBS) 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 cooperative effort that also includes the West German Bundesanstalt

fur Mater ialprufung

.

7 . 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 determine the galling behavior of metals. Tests and

measurement methods developed at NBS are currently being employed to

evaluate alloys used in agricultural and industrial equipment where

galling wear is a serious problem.

8. DePuy Manufacturing Company, Inc.

Todd Smith of DePuy Manufacturing Company, Inc. has cooperated with

NBS (A. C. Fraker) in research designed to study the mechanical and

electrochemical effects of applying sintered porous coatings of

Co-Cr-Mo to Co-Cr-Mo substrates. Specimens involving extensive

preparation and modelled after industrially produced prosthetic

devices were provided.

9. C. S. Draper Laboratory, Inc.

Studies are underway involving the evaluation of an idea for an improved microstructural design for beryllium. The goal is to reduce

"dimensional instability," time dependent shape distortion, by means

86
of reduced agglomeration of the dispersed phases. Mechanical

properties being considered are: dimensional instability, the Micro

Yield Strength (1 x 10 offset value), and the coefficient of linear

thermal expansion. All three properties critically determine the

navigational precision of "instruments" constructed of beryllium.

C. S. Draper Laboratory, Inc. has supplied materials in the form of

test samples and funding. NBS continues to provide the necessary

measurement capability and interpretation of the data. This is a collaboration between K. Kaplesh and J. McCarthy (both of Draper) and

R. Polvani (NBS).

10. 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.

11. Howmedica, Inc.

Larry Gustavison of Howmedica, Inc. has cooperated with NBS

(A. C. Fraker) and provided sintered porous coated Co-Cr-Mo research

materials and devices for use in metallurgical studies. He also

provided the Co-Cr-Mo material used for the Standard Reference

Material 1891.

12. Industrial Technology Research Institute

A corrosion specialist from Materials Research Laboratories,

Industrial Technology Research Institute of Taiwan, has spent several

months at NBS in the Corrosion Group cooperating in a study of

acoustic emission as a diagnostic method for detecting stress

corrosion cracking.

13. International Business Machines

The International Business Machines Corporation is sponsoring a project at NBS (D. Lashmore and L. Bennett) dealing with the magnetic

properties of electrodeposited artificial super lattices.

14. Lockheed Corporation

A collaborative effort is underway between the Lockheed Research

Laboratory of Lockheed Corporation (R. Lewis and A. Joshi) and NBS

(R. Shull) to prepare metastable magnesium alloys via rapid

solidification and to determine their structures and corrosion

resistance. Significant enhancement of transition metal solubilities

in magnesium have been obtained which may lead to large reductions in

the rates of atmospheric attack of these alloys.

87
15.

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.

16. Magnaflux Corporation

The Nondestructive Characterization Group has continued an interaction

with the Magnaflux Corporation advising them on materials selection

and high temperature ultrasonic couplant alternatives for emerging

steel sensors.

17. Minnesota Mining and Manufacturing Company

D. P. Smith of Memory Technologies Laboratory, Minnesota Mining and

Manufacturing Company, and R. Polvani (NBS) are collaborating on a means of characterizing the mechanical properties of "floppy" disk

coatings. The ability of disks to store information depends on both

the recording/reading head maintaining intimate contact with the

magnetic coating and using coatings as thin as possible. The pressure

needed to maintain contact and thinness of the coating causes a serious durability problem. Dynamic Microindentation Instrument

load-depth curves are providing a unique means for understanding the

mechanical performance of the coating/disk system.

18. National Association of Corrosion Engineers

The technical activities of the collaborative National Association of

Corrosion Engineers-National Bureau of Standards (NACE-NBS) Corrosion

Data Program are centered at NBS. This program is providing

scientists and engineers with computerized corrosion data. NACE has

recently delivered to users the first products of the cooperative

program -- a floppy disk corrosion database. The floppy disk package

with search capability presents uniform corrosion data for alloys in

aqueous environments as graphs and tables showing corrosion rate as a function of concentration and temperature of the environment. A

second floppy disk database on non-metals is also near completion.

Projects are also underway to acquire large computerized corrosion

databases from specific industry sources. The efforts were aided

greatly by D. E. Clausen, a full-time Research Associate assigned to

the program by NACE.

19. Parker Hannifin Corporation

Research on characterizing the weldability of a leaded, resulfur ized,

rephosphorized carbon steel is being carried out in a cooperative

program between Parker Hannifin Corporation (W. Hertel), the U.S.

Coast Guard (H. Hime), and NBS (J. G. Early). This research is aimed

at establishing welding limits for this steel which is not currently

allowed in ship components. The deformation behavior of weld test

samples (prepared by Parker Hannifin) is being studied by analysis of

test results from semi-guided bond tests and wrap-bend tests.

88
20. 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 Wear and Mechanical Properties 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.

INDUSTRY/UNIVERSITY

1. National Bureau of Standards Metals Processing Laboratory

The National Bureau of Standards Metals Processing Laboratory is one

of the special facilities available at NBS to aid researchers from

industry and universities in independent or collaborative research and

testing of new materials. Such investigators can come to NBS to

participate in the preparation of special samples not readily

obtainable elsewhere. During the past year, investigators from

Lockheed, Martin Marietta, General Electric, Air Force Materials

Laboratory, Naval Research Laboratory, Bureau of Mines, Lawrence

Livermore Laboratory, Massachusetts Institute of Technology,

University of California at Santa Barbara, University of Washington,

and University of Wisconsin have participated in interactions in this

program. Collaboration with NBS scientists on metallurgical aspects

of the generic technical problems involved is often included in these

activities. Particular interest has been shown in rapid

solidification technology, where the Metals Processing Laboratory

possesses unique capabilities.

2. 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 is spending 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. Carnegie-Mellon University

W. Johnson (Carnegie-Mellon University) and P. Voorhees (Metallurgical

Processing Group) have been collaborating on a study of stress effects

on alloy coarsening. In high-strength alloys designed for use at high

temperatures, control of precipitate size and avoidance of excessive

coarsening of the alloy microstructure is important in order to

maintain high performance. This joint program in which the expertise

of W. Johnson and his students on elastic interactions in alloys is

combined with the expertise of P. Voorhees and co-workers at NBS on kinetic effects has resulted in significant progress toward evaluating

the effect of stress on coarsening processes.

89
2. Johns Hopkins University

A fruitful collaboration between Johns Hopkins University graduate

students (T. Hsieh, K. Hershman, and E. Lindgren) and NBS (M. Rosen)

has begun in the area of composite materials interface

characterization. The collaboration centers around the use of guided

stoneley waves for characterizing the elastic property gradients at

interfaces. It extends the approach of an earlier collaboration on Rayliegh wave characterization of surface elastic property gradients.

3. Johns Hopkins University

A cooperative program between Johns Hopkins University (J. Kruger) and

NBS (G. Long) for the study of the influence of alloying on the nature

of passive films has been in progress for the past year. Considerable

progress has been made in applying both ex situ and in situ EXAES

techniques to the study of the passive film on iron, and the research

is continuing at the NBS/IMSE x-ray beamline at the National

Synchrotron Light Source. One senior post-doc (D. Tanaka) and two

graduate students from Johns Hopkins are stationed at NBS.

4. Johns Hopkins University

Studies on the mechanism of transgranular stress corrosion cracking

are being pursued in cooperation with J. Kruger of Johns Hopkins

University. The experimental part is being carried out at NBS by a graduate student (T. Cassagne), and the staff of the Corrosion Group

is involved both in the experimental and in the analysis of the

results

.

5. Johns Hopkins University

A cooperative program between the Johns Hopkins University and NBS for

study of rapid solidification processes has been in progress for the

past five years. Typically, in this program rapidly solidified alloys

are produced in the NBS Metals Processing Laboratory and then

characterized by electron microscopy techniques by scientists from

Johns Hopkins (D. Shechtman and L. Bendersky). The results are jointly analyzed by the cooperating NBS and Johns Hopkins scientists

to determine the effect of rapid solidification processing on alloy

microstructure. This collaboration has recently resulted in a major

discovery of a new class of materials, quasicrystals, that do not obey

previously accepted crystallographic restrictions concerning

periodicity.

6. Massachussetts Institute of Technology

The Nondestructive Characterization Group has commenced a close

collaboration with J. Cornie and his colleagues at the Massachussetts

Institute of Technology (MIT) as part of a new SDI/SDIO program on advanced composites. The Nondestructive Characterization Group is

responsible for developing innovative methods for determining the

mechanical properties of the interfaces between metal matrix and

ceramic reinforcement in metal matrix composites.

90
7. North Carolina State University

This research is a collaborative effort between North Carolina State

University (H. H. Stadelmaier and I. K. Simonsen) and NBS

(A. C. Fraker) to determine the identity and conditions of formation

of carbides found in Co-Cr-Mo-C alloys. The results should be useful

in controlling the amounts and distribution of carbide phases in this

material.

8. University of Illinois

R. D. Shull and M. J. Kaufman, both of NBS, have been collaborating

with D. Konitzer and H. Fraser at the University of Illinois

(Urbana-Champaign) to clarify the structures of the intermetallic

compounds found in titanium-aluminum alloys. A recent notable finding

was that the previously reported T^Al phase does not exist; but is

instead a ternary phase formed on contamination with nitrogen.

9. University of Manchester -- Institute of Science Technology

A long-term study of the statistics of pit distribution and their

variations with time is being carried out in the Corrosion Group in

cooperation with the University of Manchester -- Institute of Science

Technology (UMIST) in the United Kingdom. This program is being

sponsored by the Nuclear Regulatory Commission.

10. University of Maryland

R. W. Armstrong (University of Maryland) and R. Polvani (NBS) are collaborating 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.

11. University of Virginia

A cooperative program on the electrodeposition of gallium arsenide is

being undertaken between the University of Virginia Materials Science

Department and the Electrodeposition Group (D. Lashmore).

12. University of Wisconsin -- Madison

J. H. Perepezko (University of Wisconsin) and W. J. Boettinger

(Metallurgical Processing Group) have been collaborating on problems

related to microstructure formation during rapid solidification.

Extensive experience at the University of Wisconsin on the

undercooling and nucleation behavior of liquid metal droplets has been

combined with NBS work on alloy growth kinetics to yield results which

present a more comprehensive view of how microstructures develop in

91
rapidly solidified powders and ribbons. This knowledge can be used to

tailor microstructures to meet specific alloy property requirements.

13. Vanderbilt University

A cooperative program on corrosion of amorphous alloys is being

undertaken.

92
TECHNICAL/ PROFESSIONAL COMMITTEE LEADERSHIP ACTIVITIES

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

R. Ricker, Committee on Corrosion and Environmental Effects

American Society for Metals

L. H. Bennett, Editor, "Resonance Techniques," The Metals Handbook:

Materials Characterization, Volume 10

NDT Committee

H. N. G. Wadley

Subcommittee on Metallurgical Reactions and Electromigration in

Electronic Devices

C. A. Handwerker, Chairman

Washington, DC Chapter

P. J. Blau, Chairman

A. W. Ruff, Chairman, Program Committee

American Society for Testing and Materials

B7 : Light Metals and Alloys; Aluminum Alloy Ingots and

Castings

B7.07.09: 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

E7 : Nondestructive Testing

Joint Task Group on Acoustic Emission; System Calibration

J. A. Simmons, Chairman

93
E24: Fracture Testing

C. G. Interrante, Member of Executive Committee

E24.05: Terminology for Fracture Testing

C. G. Interrante, Co-Chairman

E38: Resource Recovery

J. G. Early, Executive Committee

E38.02: Metals Resource Recovery

J. G. Early, Chairman

F4: Medical and Surgical Materials and Devices

F4.G1: Joint Section on Corrosion of Implants

A. C. Fraker, Co-Chairperson

F7 : Aerospace Industry Methods

F7.04: Hydrogen Embrittlement Testing

C. G. Interrante, Chairman, Task Group on Terminology

Gl: Corrosion of Metals

G1.06: SCC and Corrosion Fatigue

R. Ricker

Gl.ll: Electrochemical Measurements in Corrosion

R. Ricker

G2 i G2.2:

G2.9:

G2.91'

Erosion and Wear

Solid Particle Erosion

A. W„ Ruff, Task Group Leader

Executive Subcommittee Task Group on Operations

A. Wo Ruff, Chairman

Terminology and Definitions

Po J. Blau, Chairman

ASTM Committee on Nondestructive Testing

L. J. Swartzendruber , Member

L. H. Bennett, Member

ASTM Coordinating Group on Terminology for Environmental Efforts

C. G. Interrante, Convener

ASTM Standing Committee on Terminology

P. J. Blau, Chairman, Terminology Coordinating Task Group on Tribology

C. G. Interrante, Technical Committee Representative

American Society of Mechanical Engineers

Tribology Division, Executive Committee

A. W. Ruff

94
Electrochemical Society

Editorial Committee

U. Bertocci, Division Editor

Electrodeposition Division

D. S. Lashmore, Secretary-Treasurer

Federation of Materials Societies

S. R. Coriell, Trustee

G. M. Ugiansky, Trustee

G. M. Ugiansky, First Vice President/Treasurer

Awards Committee

G. M. Ugiansky, Chairman

Instrument Society of America

S. J. Norton, Session Organizer, 1986 Annual International Meeting

Interagency Strategic Materials Stockpile Advisory Group

J. G. Early, NBS Representative

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 Journal of Crystal Growth

R. L. Parker, Associate Editor

International Metallographic Society

P. J. Blau, Member of Technical Committee

International Society of Electrochemistry

TC156: Corrosion of Metals

G. M. Ugiansky, Delegate

2. Stress Corrosion

G. M. Ugiansky, Delegate

TC16A: Medical Testing

1. Terminology

C. G. Interrante, Delegate

Committee on Fuel Cell Materials Technology in Vehicular Propulsion

U. Bertocci, Liaison Representative

95
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

Materials Science Division

R. Ricker, Committee on Corrosion and Environment Effects

R. Ricker, Executive Committee, Notre Dame, South Bend, IN, Chapter

Student Affairs Coordinator

Mechanical Failures Prevention Group

Committee on Mechanisms of Failure

J. G. Early, Chairman

National Association of Corrosion Engineers (NACE)

E. N. Pugh, Director, ex officio. Board of Directors

E. N. Pugh, Research Committee, Chairman

R. Ricker, Reviewer, Corrosion '86 Symposium on New Electrochemical

Techniques

R. Ricker, Reviewer for Journal: Corrosion -- The Journal of

Science and Engineering

R. Ricker, Review Board for the Journal: "Materials Performance"

T.l Corrosion Control in Petroleum Production

T.1D Corrosion Control by Chemical Treatment

R. Ricker, Unit Committee

T.1D.26 The Role of Bacteria in Corrosion

R. Ricker, Task Group

T.3 Corrosion Science and Technology Committee

T.3E R, Ricker, Unit Committee on SCC and Corrosion Fatigue

T.3L R. Ricker, Unit Committee on Electrochemical Techniques

T.3.1 Computers in Corrosion

Ann Van Orden, Vice Chairman of Task Group

G. M. Ugiansky, Director, ex officio. Board of Directors

96
Government Affairs Committee

G. M. Ugiansky, Chairman

Strategic Planning Committee

G. H. Ugiansky, Chairman

1986 Conference on Magnetism and Magnetic Materials

L. H. Bennett, Member, local committee

L. H. Bennett, Local Treasurer

Office of Energy-Related Inventions, National Bureau of Standards

L. H. Bennett, 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

U.S. Department of Transportation

Technical Safety Standards Committee

J. H. Smith, Secretary

Versailles Advanced Materials and Standards

Subcommittee on Wear

A. W. Ruff, U.S. Representative

97

U.S.

DEPARTMENT

OF

COMMERCE

National

Bureau

of

Standards

A 1

Suxpuad

-[FAOjddv*
A2
NBS-114A (REV. 2»8C

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET ( See in struction s) 4. TITLE AND SUBTITLE

1. PUBLICATION OR 2 REPORT NO.

NBSIR 86-3438

. Performing Organ. Report No. 3. Publication Date

OCTOBER 1986

Metallurgy Division Annual Report 1986

NBSIR 86-3438

5. AUTHOR(S)

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions) 7. Contract/Grant No. national bureau of standards

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City. State. ZIP)

10.

SUPPLEMENTARY NOTES

I | 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 1986 activities of the Metallurgy Division of the

National Bureau of Standards. The research centers upon the structure-processingproperties relations of metals and alloys, and on the methods of their measurement.

Efforts comprise studies of synchrotron radiation research for materials

characterization, metallurgical processing, wear and mechanical properties, chemical

metallurgy, corrosion and protection of metals, electrodeposition, nondestructive

characterization, and magnetic materials. The work herein described includes three

cooperative data programs with American professional societies and industry: the

American Society for Metals-NBS Alloy Phase Diagram Program, the National

Association of Corrosion Engineers-NBS Corrosion Data Program, and the American

Iron and Steel Institute-NBS Steel Sensor Program. The scientific publications,

committee participation, and other professional interactions of the 86. full-time

and part-time members of the Metallurgy Division and its 70 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 14. NO. OF

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