Reference

NBS

PUBLICATIONS

AlllOLi 0342fiS

Institute for Materials Science and Engineering

METALLURGY

NBSIR 85-3191

U.S. Department of Commerce

National Bureau of Standards

-QC

100

• U56

85-3191

1985

Technical Activities

1985
Superimposed selected area diffraction and convergent beam

diffraction patterns of aluminum-maganese icosahedral phase

revealing true 5 -fold symmetry

Microscopy by R. J. Schaefer and L. Bendersky
Institute for Materials Science and Engineering

ME1ALIJURGY

E. N. Pugh, Chief

J. G. Eariy, Deputy

NBSIR 85-3191

U.S. Department of Commerce

National Bureau of Standards

Technical Activities

1985
METALLURGY DIVISION

CHIEF

E. Neville Pugh

Phone: (301) 921-2811

DEPUTY CHIEF

James G. Early (Acting)

Phone: (301) 921-2811

GROUP LEADERS

Structure Characterization

Masao Kuriyama

Phone: (301) 921-2986

Metallurgical Processing

John R. Manning

Phone: (301) 921-3354

Wear and Mechanical Properties

Arthur W. Ruff " Phone: (301) 921-2966

Chemical Metallurgy

James G. Early (Acting)

Phone: (301) 921-2982

Corrosion

U. Bertocci (Acting)

Phone: (301) 921-2094

Electrodeposition

David S. Lashmore

Phone: (301) 921-2958

Nondestructive Characterization

Haydn N. G. Wadley

Phone: (301) 921-2956

ii
ABSTRACT

This report summarizes the FY 1985 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. Task efforts

comprise studies of synchrotron radiation research for materials

characterization, metallurgical processing, wear and mechanical

properties, chemical metallurgy, corrosion and protection of metals,

electrodeposition, and nondestructive characterization.

The work herein described also includes three cooperative data 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.

The new Institute for Materials Science and Engineering beam lines

at the National Synchrotron Light Source were commissioned this

year and the first synchrotron radiation experiment successfully

completed. The feasibility of the new piezoelectric sensor developed

under the AISI-NBS Steel Sensor Program for detection of porosity

in steel was demonstrated. This new technology was turned over to

Argonne National Laboratory for development of a field system.

The scientific publications, invited talks, committee participation,

and other professional interactions of the 91 full-time and part-time

permanent members of the Metallurgy Division and its 33 guest re- searchers are identified.

iii
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TABLE OF CONTENTS

PAGE

OVERVIEW 1

METALLURGY DIVISION

ORGANIZATIONAL CHART 9

RESEARCH STAFF 10

TECHNICAL ACTIVITIES

Structure Characterization 15

Metallurgical Processing 23

Wear and Mechanical Properties 35

Chemical Metallurgy 45

Corrosion 51

Electrodeposition 61

Nondestructive Characterization 71

Magnetic Materials 85

OUTPUTS/INTERACTIONS

Recent Publications 86

Industrial and Academic Interactions ... 96

Technical/Professional Committee 102

Leadership

Associated Activities . 106

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, Acting Deputy Chief

June Toms, Secretary

The Metallurgy Division conducts fundamental research on the structureproperties-processing relations of metals and alloys, and on the methods

of their measurement. It also evaluates data, compiles data bases, and

produces standard reference materials. It performs these activities for

the benefit of American industry, government, and universities. Within

the Division the work is carried out in seven discipline or interestoriented groups.

The National Bureau of Standards/Institute for Materials Science and

Engineering (NBS/IMSE) part of the National Synchrotron Light Source

(NSLS) was commissioned this year. The first synchrotron radiation ex- periment using white radiation was conducted in March 1985. Scientists in

the Structure Characterization Group completed the alignment of the monochromator system so that either white radiation or tunable monochromatic

radiation is available. Initial experiments have confirmed the high

resolution achievable with the small eraittance source at NSLS. A significant

new effort to develop a high resolution x-ray image camera has been started.

This direct detection camera, based on a charge coupled device (CCD) area

sensor, has the potential for providing both good spatial resolution and

high sensitivity for NDE radiography.

Continuing studies of new phenomena produced during rapid solidification

have been directed towards developing materials with improved properties or potential for improved properties not attainable by conventional means.

Extensive studies of the conditions necessary for the formation of a new

alloy phase, a quasicrystalline Al-Mn phase, with five-fold point group

symmetry have been carried out. A second quasicrystalline phase exhibiting

decagonal or ten-fold symmetry was discovered under certain solidification

conditions. Recent studies of diffusion-induced grain boundary motion

(DIGM) and liquid phase sintering have identified diffusion induced co- herency strains as the driving force.

The initial studies using the new materials characterization technique

of thermal wave microscopy detected density differences in the wear

debris from sliding contact surfaces which may be related to the observed

differences between reversed and unidirectional sliding. A new standard

reference material, No. 1891, has been issued for corrosion studies of

synthetic implant alloys. A highly reliable acoustic emission technique

has been developed for inspection of large pressure vessels.

The collaborative effort with the American Society for Metals (ASM) in

the ASM/NBS Alloy Phase Diagram Data Center continues to provide critically

evaluated phase diagrams. During the year, thirteen titanium, seven

1
aluminum, and three iron based binary systems were evaluated by NBS

scientists. Dr. J. Murray of NBS is now the editor of the Bulletin of

Alloy Phase Diagrams. A major new effort was initiated to digitize

over 1500 binary phase diagrams for the new ASM compendium to replace

the compilations of Hansen, Elliott, and Shunk. Scheduled for com- pletion the end of 1985, this enlarged data base will contain consistent

pure element properties, nomenclature, diagram style, and format.

Mechanistic studies of corrosion processes continue to focus on environmentally induced cracking (both stress corrosion cracking and

hydrogen embrittlement) and pitting. A new, computerized, portable

corrosion measuring system was placed in field testing by measuring

the corrosion of bridge decks and steel pilings. A new program was initiated for the Nuclear Regulatory Commission (NRC) in support

of NRC's program to identify a permanent solution to the problem of

nuclear waste disposal.

The NACE-NBS Corrosion Data Center expanded its efforts in the three

pilot projects on kinetic data for atmospheric corrosion, localized

corrosion, and uniform corrosion. Modifications to the graphics

software has increased the flexibility of the data display to include

greater accessibility and data manipulation. Techniques such as windowing, autoscaling, and statistical analysis are now available.

A very successful Corrosion Data Workshop was organized with strong

industry participation to address the corrosion data needs of users. Using the fund raising technique of the ASM-NBS Alloy Phase Diagram

Data Center as a model, efforts have been initiated through the

Secretary of Commerce to enlist the participation of the chief

executive officer or similar top management of a major corporation to

lead the private sector fund raising for the Corrosion Data Center.

Production of Standard Reference Materials by the Electrodeposition

Group continues to provide important support to the industrial sector.

Corrosion step-test standards for evaluating electroplated parts are now available to the automotive industry. A recently developed mathematical model of the alloy deposition process predicts the composition

of multi-component deposition by either pulsed or direct current.

Composition modulated alloys (CMA) with layer spacings as low as 1 nm

have been provided by electrodeposition. An automated microhardness

system has been developed that provides hardness data as well as information on other aspects of deformation.

The collaborative program with the American Iron and Steel Institute

(AISI) to develop sensors for the steel industry has led to the successful demonstration of an ultrasonic sensor for detecting porosity in hot

steel ingots. A prototype system is currently undergoing field trials.

A new program has been initiated in the Nondestructive Characterization

Group to develop NDE techniques for characterizing fiber/matrix interfaces in metal matrix composites. Continued efforts to develop non- contacting measurement techniques has concentrated on laser/EMAT systems

which have been successfully demonstrated on steel at 750°C.

2
A new activity in magnetic materials was started in the Metallurgy Division

this year under the leadership of Dr. L. H. Bennett. Focus is on the properties of both soft and hard magnetic materials. Of particular concern for

soft materials are magnetic thin films, especially compositionally modulated

alloys where proximity effects and local anisotropies will dominate. For

hard magnets, concern has centered on the relationship between the real space

atomic topology and the occurrence of local site magnetic moments. A new

laboratory for the measurement of ac magnetic susceptibility was established.

This technique provides information not generally available from dc measurements. Attention is currently being addressed to obtaining coil designs

useful to the measurement of magnetic thin films.

The Division was staffed in 1985 by 91 full-time and part-time permanent

people. In addition, there were 33 guest researchers and research associates

in residence during the past year who collaborated with Division scientists

on various studies.

3
The activities of the Division are formally identified in eight tasks

which largely parallel the objectives of the seven groups. These tasks

are listed below. The major accomplishments associated with each of

these tasks, and a fuller description of task-related activities follow.

Task 2 6 10 5-- SYNCHROTRON RADIATION RESEARCH FOR MATERIAL SCIENCE . Relates to joint NBS/Naval Research Laboratory x-ray instrumentation

complex at the National Synchrotron Light Source, and its use to perform microstructural characterization.

Task 15442—STRUCTURE CHARACTERIZATION . Addresses activities in the

application of synchrotron radiation to materials science, with

particular emphasis in microstructural details for evaluation of

materials quality processing, and new materials design. Also addresses the activities on analytical electron microscopy to com- plement the evaluation performed by radiation.

Task 1 5443—METALLURGICAL PROCESSING . Contains most of the Division's

competence in rapid solidification, surface modification, interface

stability and measurement, and the Diffusion in Metals Data Center.

Task 15444—WEAR AND MECHANICAL PROPERTIES . Focused on measurement

methods, understanding, and predictive methodology of tribology. It

also includes research on synthetic metal implants.

Task 15445—CHEMICAL METALLURGY . Contains all activities related to

the ASM/NBS Alloy Phase Diagrams Program including data/bibliographic

base compilations, graphics, phase system evaluations, and modelling,

and the publication of the Bulletin of Alloy Phase Diagrams.

Task 15446—CORROSION AND PROTECTION OF METALS . Relates to major

focused effort on study of corrosion in metals, including predictive

models and measurement methods. Now contains all activities related

to NACE/NBS Cooperative Program for Corrosion Data.

Task 1 5447—ELECTRODEPOSITION (ELECTROCHEMICAL PROCESSING).

Covers all Division activities in electrodeposition, and its processing/structure/ properties relations. Also covers electrodeposited Standard Reference Materials for hardness, thickness,

and crack dye-penetrant.

Task 15448—NONDESTRUCTIVE CHARACTERIZATION . Addresses activities

in nondestructive evaluation and processing control. Includes work

on acoustic sensing, including that related to the new cooperative

American Iron and Steel Institute (AISI) program.

4
FY 85 Significant Accomplishments

Task 15442—ADVANCED MICROSTRUCTURE CHARACTERIZATION.

Task 26105—SYNCHROTRON RADIATION RESEARCH FOR MATERIAL SCIENCE.

o The IMSE synchrotron radiation beam lines were commissioned on March 5, 1985 and "stand-alone" status established on May 11, 1985.

o First synchrotron radiation experiment, using white radiation

beam, was carried off at NBS/IMSE X-23A beamline of NSLS on March 5-7, 1985, to establish the selected area diffraction/

microradiograph technique in real time.

o Monochromatic real time topographic capability was established on May 9-22, 1985. An assessment of the crystal perfection of the

electro-optical materials was made.

o The experimental confirmation of the x-ray Raman EXAFS of low Z elements was carried out using hard radiation.

o An atomic scale model for rapidly cooled Al-Mn alloys with icosahedral symmetry based on internal modulations was proposed.

o Dental microradiographic techniqiues were used to reveal detailed

structural features in teeth.

Task 15443—METALLURGICAL PROCESSING.

o A new alloy phase that shows 5-fold icosahedral symmetry both in

its electron diffraction pattern and growth morphology was discovered as a result of a cooperative program on rapid solidification

between NBS and The Johns Hopkins University. This icosahedral

Al-Mn phase belongs to a new class of materials that are neither

crystalline, since crystallography does not allow periodic crystal

lattices with 5-fold symmetry, nor amorphous.

o Ouasicrystals have been produced in the NBS Metals Processing

Laboratory by all three major rapid solidification techniques,

melt-spinning, surface melting with subsequent rapid re-freezing,

and atomization, and have been found in a number of different

alloy systems.

o The effect of container side walls on the convection produced

during directional solidification was analyzed. It has been

assumed that side walls will reduce convection because of forces

between the side walls and the flowing fluid. It was found that

there are regimes where the presence of side walls will instead

increase alloy convectional instabilities.

5
o A driving force arising from the effect of diffusion-induced

coherency strains has been identified as responsible both for

diffusion-induced grain boundary migration and for liquid film

migration that occurs during liquid phase sintering. This result

has significant implications for surface alloying to produce

protective coatings and for diffusional interactions at interfaces

in composite materials.

o Coarsening of the microstructure in rapidly solidified Al-8 wt%

Fe powder was measured. The rate of coarsening depended strongly

on the original powder microstructure, which in turn depended on the original powder particle size. The slowest, most desirable

coarsening regimes were found in alloy samples having the smallest

original particle diameters.

Task 15444—WEAR AND MECHANICAL PROPERTIES.

o Application of the new technique of thermal wave microscopy (TWM)

to the study of wear debris accumulations on sliding contact

surfaces was accomplished. TWM of wear tracks on an oxidized Cu15 wt.% Zn alloy showed evidence for periodic density differences

in debris compacts. The presence of such compacts may help explain

the differences in the frictional running-in behavior between re- versed sliding and unidirectional sliding.

o Standard reference material 1891, a Co-Cr-Mo material for use with

ASTM F 746, was completed and is now available for monitoring the

corrosion behavior of that alloy and similar synthetic implant

alloys. Corrosion and fatigue data from porous metal coated

surgical implant metals show effects of porous coating production

on material properties and indicate microstructural changes to be

avoided during processing steps on such alloys.

o Design and test criteria based on fracture mechanics analysis were developed to establish the basis for constructing seamless pressure vessels from significantly higher strength steels while maintaining the same level of safety. A technique has been developed

for the use of acoustic emission to periodically inspect large

pressure vessels.

o A method has been developed for the quantitative measurement of the

severity of galling wear damage. The method employs topographic

parameters obtained from data acquired by means of an automated

profilometer system developed at NBS. The system permits quantitative assessment of the amount of galling damage, and the

results can then be compared with others using different test

methods or involving other alloys.

6
Task 15445—CHEMICAL METALLURGY

o Graphics programs to provide publication quality diagrams for the

Bulletin of Alloy Phase Diagrams and provide input program for

the phase diagrams database were made fully operational.

o An inter-phase diagram database has been set up to allow for efficient searching of the metallurgical important information

embedded in a phase diagram. This subset is extracted by a newly

written program which performs a topological analysis of the

curves in the phase diagram.

o Graphing algorithms to allow isotherms or isopleth representation

of ternary phase diagrams have been developed. Algorithms which

allow real time translation and rotation of diagrams on the (b/w)

Evans and Sutherland terminal are now available.

o Theoretical and experimental results in the area of magnetic

particle inspection led to the incorporation into a new military

standard of a new method for using Hall-effect probes to determine proper magnetization levels for effective inspection.

Task 15446—CORROSION AND PROTECTION OF METALS.

o Substantial progress has been made towards understanding the

discontinuous nature of cleavage crack propagation in ductile

fee alloys undergoing transgranular stress corrosion cracking.

o Modeling of the chemistry and electrochemistry inside transgranular cracks has been extended to CuAu alloys in chloride

solutions. The results confirm that hydrogen embrittlement can

be excluded as a cause of brittle fracture.

o Portable computer systems have been developed to measure cor- rosion rates in the field and are being used to monitor the

corrosion of steel reinforcing bars in concrete bridge decks

and underground steel pilings.

o A Corrosion Data Workshop, organized jointly with the National

Association of Corrosion Engineers (NACE), was attended by

approximately fifty corrosion specialists from industry, government, and academe; the Proceedings will be used to help direct

the future activities of the NACE-NBS Corrosion Data Program.

o Analysis of the statistical properties of the random fluctuations of the passive current during pit initiation has shown

that the process cannot be modeled by renewal processes or homogeneous Markov chains, but more complicated stochastic

models have to be employed.

7
Task 1 5447 —ELECTRODEPOSITION (ELECTROCHEMICAL PROCESSING)

o The first stage of a mathematical model of the

alloy deposition process taking into account diffusion migration

and convection was completed. The model is capable of predicting

composition of alloys of up to 15 components using pulsed or direct current. The model was tested for the electrodeposition

of Sn-Pb (solder). Future work will focus on the effects of the

substrate on exchange current and on nucleation and growth.

o Electrodeposition from a single electrolyte produced composition

modulated alloys of copper—nickel and nickel-palladium with

layer spacings as low as lnm. Comparison made between potentiostatic and galvanostatic deposition indicated that potentiostatic

deposition provided significantly sharper interfaces.

o Development and production of 150 corrosion step-test Standard

Reference Materials samples were completed and have now been

made available to the automotive industry.

o An automated microhardness system was developed and was shown to

be capable, not only of measuring microhardness but also of yielding information on modulus and ultimate tensile strength.

Task 15448—NONDESTRUCTIVE CHARACTERIZATION.

o Research on an ultrasonic sensor for detecting gross porosity/pipe

in hot steel ingots has been completed, and a prototype system

incorporating the NBS approach is undergoing trials at the Argonne

National Laboratory.

o Improved tomographic algorithms for reconstructing internal temperature distributions have been developed and successfully

experimentally evaluated on austenitic stainless steel samples

at temperatures up to 750° C.

o Noncontact laser/EMAT measurement methodologies for high temperature ultrasonic sensors have been developed and successfully

tested on steel up to 750° C.

o The eddy current inverse problem of determining the depth profile

of the electrical conductivity has been implemented and applied

to laboratory models.

8
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RESEARCH STAFF

Beauchamp, Carlos R. © Computer simulation of electrodeposition

processes

© Electrochemical measurements of kinetic

parameters

© Corrosion measurements of electrodeposited

coatings

Bertocci, Ugo © Electrochemical measurements

© Computer modeling

© Passivity and pitting

Biancaniello, Francis S. © Special alloy and quasicrystal preparation

© Melt-spinning rapid solidification

© Inert gas atomization and metal powder

processing

Black, David R. © Inelastic x-ray scattering

© Energy dispersive x-ray diffraction

© X-ray optics

Blau, Peter J. © Friction and wear transitions

© Wear microstructure relations

© Microindentation and scratch hardness

Boettinger, William J. © Rapid solidification

© Alloy microstructural characterization

© Relation of alloy microstructures to

processing conditions

Brown, Henrietta J. © Coating thickness SRM development

© Simultaneous thickness electropotential

(STEP) SRM development

Burdette, Harold E. © X-ray optics engineering

© Crystal growth

© Instrumentation

Clough, Roger B. © Acoustic emission

© Mechanical properties

© Surface modification

Coriell, Sam R. © Modeling of solidification processes

© Interface stability

© Convection and alloy segregation during

solidification

Dobbyn, Ronald C. © X-ray dynamic imaging

© X-ray optics

© Synchrotron radiation instrumentation

IQ
Early, James G. , Jr. © Powder metallurgy

© Hot isostatic pressing

© Ferrous alloys and resource recovery

Escalante, Edward © Corrosion rate measurement for practical

applications

© Underground corrosion

© Atmospheric corrosion

Fraker, Anna C. © Titanium alloys

© Corrosion processes

© Transmission electron microscopy

© Surgical implant metals

Handwerker, Carol A. © Interface studies

© Diffusion-induced grain boundary

migration

© Liquid film migration

Hardy, Stephen C. © Alloy coarsening

© Surface tension measurements

© Interface segregation

Harris, Jonice S. © Scanning electron microscopy

© Fatigue properties measurements

© Wear and friction properties

Interrante, Charles G. © Hydrogen embrittlement

© Nuclear waste disposal

© Environmental testing

Ives, Lewis K. © Wear of metals

© Transmission electron microscopy

© Erosion of metals

Johnson, Christian E. © Ultra-black coatings

© Electroless deposition processes

© Metallic glass alloy deposition

© Microhardness SRM research

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

© Prepare computer graphics for phase

diagrams

Kahn, Arnold H. © Eddy current modeling

© Electromagnetic theory

© Solid state physics

Kaufman, Michael J. © Physical Metallurgy

© Electron Microscopy

© Stress Corrosion Cracking

11
Kelley, David R.

Kuriyama, Masao

Lashmore, David S.

Linzer, Melvin

Long, Gabrielle G.

Manning, John R.

Mauer, Floyd A.

McAlister, Archie J.

Mullen, Jasper L.

Murray Joanne L.

Norton, Stephen J.

© Microhardness SRM development

© Dye penetrant SRM development

© Precious metal electrodeposition

© Scattering physics

© Solid state physics

© Crystallography

© Electrochemical mechanisms of coating

processes

© Pulsed alloy deposition

© Composition modulated alloy deposition

© Properties and structure of

electrodeposited coatings

© Ultrasonic imaging

© Acoustic emission

© Ultrasonic scattering

© X-ray scattering physics

© X-ray absorption spectroscopy

© Disordered materials

© Metallurgical processing

© Diffusion kinetics

© Interface migration

© Ultrasonic tomography

© X-ray diffraction

© Ultrasound-microstructure relations

© Differential thermal analysis

© Equilibrium phase diagrams

© Enthalpy and kinetics of metastable phase

transformat ions

© Evaluation of binary and higher order

phase diagram data

© Development of automated hardness testing

© Electrochemical measurements for

determining metal corrosion

© Analytical spectroscopy

© Thermodynamic modeling of alloy phase

diagrams

© Data evaluation for Ti and Al-based alloy

systems

© Editor, Bulletin of Alloy Phase Diagrams

and Constitution of Binary Alloys

© Computer database development for alloy

phase diagrams

© Ultrasonic imaging

© Inverse modeling

© Dimensional resonance tomography

12
Olson, Craig D.

Parker, Robert L.

Polvani, Robert S.

Pugh, E. Neville

Ridder, Stephen D.

Ruff, Arthur W.

Schaefer, Robert J.

Shull, Robert D.

Simmons, John A.

Smith, John H.

Spal, Richard D.

Stockton, Charlotte K.

o Scanning electron microscopy

© X-ray microanalysis

© Thermal wave microscopy

© Ultrasonic detection of solid/liquid

interface, interface kinetics

© Applications to alloys, continuous

casting, metallography, solidification

© Mechanical behavior

© High temperature strengthening mechanisms

© Microindentation measurements

© Dimensional instability behavior

© Mechanistic studies of SCC

© Electrochemistry of localized

environments

© Physical metallurgy

© Microparticle rapid solidification

© Solidification dynamics

© Inert gas atomization

© Wear and friction

© Microstructure effects

© Mechanical behavior

© Microscopy

© Quasicrystals

© Electron beam rapid solidification

© Convection and interface effects during

solidification

© X-ray and neutron diffraction

0 Physical metallurgy

© Environmentally induced cracking

© Electron microscopy

© Dislocation theory

© Acoustic emission

© Inverse modeling

© Mechanical properties of materials

© Fracture of materials

© Structural integrity analysis

© X-ray imaging

© X-ray optics

© Instrumentation

© Rapid solidification

© Alloy characterization

© Quasicrystals

13
Swartzendruber, Lydon J. o

©

©

Magnetic methods, NDE

Gamma-ray resonance spectroscopy

Iron binary phase diagrams

Ugiansky, Gilbert M. © Corrosion data evaluation and

dissemination

© Computer database management

© Slow strain rate testing

Van Orden, Ann C. © Corrosion data collection and

evaluation

© Marine corrosion

© Localized corrosion

Voorhees, Peter W. © Coarsening phenomena

© Elastic effects during pahse

transformations

© Anisotropic interface effects

Wadley, Haydn N. G. © Dislocations and fracture

© Acoustic emission

© Ultrasonics
ADVANCED MICROSTRUCTURE CHARACTERIZATION

Task 15442

SYNCHROTRON RADIATION RESEARCH FOR MATERIALS SCIENCE

Task 26101

Important new materials in industry are produced by far more sophisticated

control and processing methods than heretofore utilized. Coupled with increased national emphasis on quality control and automation for increased

productivity, these advanced materials require a new, wide range of atomistic

structural determination techniques and raicrostructural characterization

methods as well as new techniques to utilize well-controlled solid-state

engineering. The objectives of Task 15442 and Task 26101 are to address

this challenge through the development of measurement methods and

standards for the advanced quantitative characterization of metallurgical

microstructures and other high-tech materials. Methods in these tasks are primarily centered around the use of synchrotron radiation and x-ray scattering principles. The research coverage is, therefore, quite wide, ranging

from the atomic structural determination of disordered materials and films,

through studies of solidification processes, nondestructive evaluations of

flaws and strains in materials, microstructural characterization of films

and high-tech materials, to a study of the structural features of human

teeth.

These tasks are related directly 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 has contributed

to the support of this effort, in particular, in the areas of data

processing and image detector development for real time observations. This

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 a synchrotron radiation facility

for NBS and NRL scientists at the National Synchrotron Light Source (NSLS),

Brookhaven. In FY85, scientists from the Structure Characterization Group

have been working on a regular basis at NSLS to commission the IMSE synchrotron radiation beam lines.

FY 85 Significant Accomplishments

o The IMSE synchrotron radiation beam lines were commissioned on March

5, 1985 and "stand-alone" status established on May 11, 1985.

o First synchrotron radiation experiment, using white radiation beam,

was carried out at NBS/IMSE X-23A beamline of NSLS on March 5-7,

1985, to establish the selected area diffraction/microradiography

technique in real time.

o Monochromatic real time topographic capability was established on May

9-22, 1985. An assessment of the crystal perfection of electro-optical

materials was made.

o The experimental confirmation of the x-ray Raman EXAFS of low Z element ; was carried out using hard radiation.

15
o An atomic scale model for rapidly cooled Al-Mn alloys with icosahedral

symmetry based on internal modulations was proposed.

o Dental microradiographic techniques were used to reveal detailed

structural features in teeth.

Commission of the NBS/IMSE X-23A BEAM Lines at NSLS

Subtask 1 of Task 15442 and

Subtask 1 of Task 26101

R. C. Dobbyn, D. R. Black, R. D. Spal, H. E. Burdette, G. G. Long and

M. Kuriyama

On March 5, 6 and 7, 1985, NSLS operated the x-ray storage ring at 2.045

Gev with a current starting at 9mA down to 4mA. This low current beam

is called an "alignment beam" for the alignment of experimental stations

and instruments for individual Participating Research Teams (PRTs). After

the beam transport pipes and experimental stations were aligned for the

NBS/IMSE beam lines (NBSX-23A) , scientists in the Structure Characterization Group took advantage of the availability of this beam to perform an experiment using white radiation.

The purpose of this experiment was to establish the real time selected

area diffraction technique for multigrain materials combined with microradiography. An imaging detector was positioned to view a radiographic

image of an Al-5 wt.% Sn multigrained sample 1.5 mm thick, while Laue

spots from the sample were observed by the same detector. With a 6 mm

aperture, multigrains were observed in the radiographic image (non diffracted forward direction image), and many Laue spots appeared associated

with these differently oriented grains. Inserting a pinhole apperture

(~ 1 mm in diameter), one grain was located in the radiographic image.

Then the number of Laue spots seen on the screen was reduced to give the

orientation of this grain. Mapping of the grain orientation was completed

by positioning the pinhole apperture onto each visible grain. The

ability to determine and follow the relative orientation of growing (or

shrinking) adjacent grains and the change in their grain boundaries is

valuable in various materials science problems, such as liquid-phase

sintering, grain boundary migration, grain coarsening and recrystallization.

In spite of the weak synchrotron radiation beam in this running period,

the experiment was successful to prove the potential value of this technique.

During the period of May 9 to May 22, NSLS provided, for the first time,

usuable synchrotron radiation beams (almost 13 hours per day) for experimenters. Scientists in the Structure Charcterizatrion Group utilized

this opportunity to complete the set-up and alignment of a monochromator

system and the topography station. Either white radiation or tunable

monochromatic radation is provided in this station. Debugging and re- finement of this beam line continues, but various experiments can now

be carried out.

16
In this beam running period, the characteristics of the NSLS synchrotron

radiation beam were measured. This provides valuable information, particularly on the source size, for the planning of experiments in the

regular running periods. Also, a routine monochromatic radiation topography capability has been commissioned. Synchrotron radiation was produced

at about 60 mA, 2.4 Gev and a fill (uninterrupted duration of available

beam) normally lasted 3 to 4 hours, with 3 to 4 fills a day. Monochromatic

radiation topography was employed to study the microstructure of advanced

electro-optic single crystals, in collaboration with a scientist in the

ceramics division. The structural perfection of lithium niobate crystals

was investigated as a function of growth direction and selected processing

parameters. Since some samples of very high quality were evaluated, it

now becomes possible to measure the quantitative effects of processing

technology. Filamentary raicrostructures of the size 1 pm or longer

were observed among the high quality samples grown from the congruent

melt. Research is being carried out on these filamentary microstructures

in samples processed by an improved stoichiometric optimization technique.

Experiments on bismuth silicate single crystals yielded extraordinary topographs (figure 1) showing evidence of very unusual "moire" type patterns.

These crystals did not show any evidence of imperfection under an optical

microscope or under infrared microscopy. However, the topographs clearly

show dislocations, regular grain boundaries, almost coherent coexistence

of two domains, in addition to the imperfect surface treatment. Although

these data are still being analyzed, they are early evidence of the high

resolution results that can be achieved with the small emittance source

at NSLS.

Inelastic X-Ray Raman EXAFS of Low Z Elements in Materials using Hard

Radiation

Subtask 2 of Task 15442

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

The detection of atoms of low atomic number, such as carbon, phosphorus,

sulfur and etc., in materials is required to determine the overall properties of the materials. The mere identification of these species, normally obtained by Auger spectroscopy, is not sufficient to determine their

precise role within the materials. The chemical and electronic states of

these atoms in their environment must be determined. For this purpose.

Extend X-Ray Absorption Fine Structure (EXAFS) measurements tuned to these

elements are desirable. However, the wave length of radiation that excites

their K-shell electrons is quite long. For such soft radiation, ultra

high vacuum systems are required to deliver radiation and collect data.

Normally, these clean beam lines do not permit "dirty" real materials in

the systems.

When hard radiation is scattered by a sample, it experiences inelastic

scattering as well as elastic (coherent) scattering. This is known, in

general, as Compton scattering; it consists of the scattering due to "free - ' electrons (traditional Compton scattering) and the scattering due to bound

17
electrons, such as K and L shell electrons. The latter is called x-ray

Raman scattering [1], [2]. The scattered radiation suffers energy losses

corresponding to the K-shell or L shell excitation. In theory, the differential cross section of the scattered radiation (as a function of

energy) is proportional to the absorption cross section [3], [4]. Thus,

the measurement of the energy spectrum of scattered radiation yields the same information as absorption spectroscopy, namely EXAFS. For low Z

elements, this principle is used to obtain their EXAFS data without using

soft radiation, thus avoiding complex experimental problems associated

with soft x-ray absorption spectroscopy. Since the harder x-ray photons

penetrate much deeper into the sample, bulk properties of low Z atoms in

materials can be measured, and sample preparation is much less critical.

Several experiments were performed using amorphous boron, amorphous carbon,

graphite, diamond and a lithium crystal to confirm the existence of EXAFS in

x-ray Raman scattering. The energy loss spectra were obtained with a double

flat crystal spectrometer using two Ge (111) crystals and a proportional

counter. The smallest step size available corresponded to a resolution of

0.2 ev/channel (step), but typically experiments were performed at 1.2

ev/channel. The incident energies of photons were 6.40 kev and 8.04 kev,

respectively for lithium and for boron and carbon. Data for boron and

carbon, with K edges at 183 ev and 277 ev, respectively, were accumulated

by the spectrometer at 1.71 ev/channel, and the spectra of lithium whose K

edge is at 54 ev were taken at 1.1 ev/channel. All of these spectra

clearly indicated the presence of the x-ray Raman scattering. Experiments

are being performed to extract the EXAFS portion of x-ray Raman scattering

spectra with better statistics.

[1] T. Suzuki, J. Phys. Soc. Jpn 22_ 1139 (1967).

[2] N. G. Alexandropoulos and G. G. Cohen, Phys. Rev. 187 455 (1969).

[3] Y. Mizuno and Y. Ohmura, J. Phys. Soc. Jpn 22^ 445 (1967).

[4] M. Kuriyama, Acta Crystall. A 27^ 634 (1971).

Atomic Structure of Rapidly Cooled Alloys with Icosahedral Symmetry

Subtask 3 of Task 15442

M. Kuriyama, G. G. Long and L. Bendersky

As part of the atomic structural research in this task, this work was undertaken to explore the unique opportunity offered by the fabrication

of an icosahedral phase alloy. A recent report [1] of the existence of an icosahedral phase with long-range orientational order and icosahedral

point group symmetry has stimulated the suggestion [2] that crystallography

should be generalized to include nonperiodic structures which retain simple

point group symmetries (i.e., which have long range correlations). Other

proposals are that the astonishing electron diffraction patterns are due to

either the existence of a real three-dimensional modulated crystal [3], or alternatively an ordered-glassy incommensurate structure [4]. [For

detailed information on the significance of this material, see Task 15443].

The objective of this work was to determine whether the diffraction data

are consistent with a fundamental aperiodicity , or if the material is more

18
correctly described as a new type of real crystal.

The experimental data consisted of a set of five diffraction patterns

taken from a single sample: a twofold pattern, a fivefold pattern,

a threefold pattern and two apparent mirror patterns. The present analysis

originated from the assumption that the new phase can be described as an imperfect crystal in which lattice translations do not necessarily hold.

This starting point should not bias the interpretation of the data because

the mathematics of icosahedral symmetry, or any other symmetry or periodicity, is not invoked.

The result of the analysis [5] is the identification of two sets of modulations in momentum space, each of which has six independent modulation

vectors. The sets of modulations are found to have the same icosahedral

angles (63.4° and 116.6°) and their magnitude are approximately in the

ratio of ;

t where t is the Golden section. After conversion to real

space, one of the sets is considered to represent "correlation distances"

rather than being referred to as ordinary modulations. Using these, an atomic arrangement was found which lead to the identification of a unit

cell for a reference cubic lattice. The two rhombohedra (pointed and flat)

commonly used in nonperiodic icosahedral models were derived, where these

rhombohedra are decorated by atomic sites on each face as well as at each

vertex. The unit cell for the reference lattice is called "icosahedral

cubic," since the properties of the icosahedral point-group are accomodated

in this unit cell. The unit cell is constructed from four flat and four

pointed rhombohedra with the lattice parameter a=0.738 nm.

Despite the conformance of the derived unit cell to icosahedral point-group

symmetry, one would not expect a cubic cell to produce the observed patterns. Since each diffraction spot was indexed by six vectors, unlike

ordinary diffraction patterns, and only three vectors define the unit cell,

three more vectors in real space are required to explain the appearance of

the point-group symmetry patterns. The explanation of these patterns lies

in the fact that, from the icosahedral cubic unit cell of the reference

lattice, additional icosahedral atomic positions are found to lead to a different length scale whose ratio to the unit cell is r . It is recognized

that the length of the original unit cell is comprised of the new length

scale cube and another smaller cube. The occupancy of the atomic sites

depends on the sequences of these cubes, thus creating local deviations

from periodicity everywhere in the material. These deviations appear in

the diffraction patterns as internal modulations, whose modulation wave

length is smaller than the unit cell length of the reference lattice.

The key is to identify the internal modulations as the external (in regular

sense) modulations through Umklapp processes. It is remarkable that the

mathematical relationship, x ^-(-1)^ t~n=L, with an integer N and a Lucas

number L, holds, and thus Umklapp processes (relating to L) always exist.

One of these modulation periodicities, N=3, agrees well with the second set

of observed modulations. It is significant that the atomic scale models

constructed via experimental analysis lead to periodic (modulated) structm-'

rather than aperiodic ones. However, successively larger periodic arrays

19
are required to complete the description of the atomic occupancy. This

suggests that the true structure is at the limit of the periodic approximations. The structure of this material consists of the three dimensionally

modulated puckered layers whose modulated frequency is not monochromatic

and which resembles in nature that of almost periodic functions.

[1] D. Shechtman, I. Blech, D. Gratias and J. W. Cahn, Phys. Rev. Lett.

53 1951 (1984).

[2] D. Levine and P. J. Steinhardt, Phys. Rev. Lett. _53, 2477 (1984).

[3] P. Bak, Phys. Rev. Lett. 54_ 1517 (1985).

[4] D. R. Nelson and S. Sachdev, Phys. Rev. B 32^ 689 (1985).

[5] M. Kuriyama, G. G. Long and L. Bendersky, Phys. Rev. Lett. _55^ 849

(1985).

Design of an X-ray Camera Using a CCD Sensor

Subtask 4 of Task 15442 and

Subtask 2 of Task 26101

R. Spal and M. Kuriyama

It is extremely important to develop an image camera with high spatial

resolution for x-ray wave length regions. This camera would make NDE

radiography and synchrotron radiation topography as easily accessible as SEM. Due to the lack of true lenses, x-ray images with fine microstructural details must be recorded on special high resolution photographic

plates that were originally developed for recording of tracks of cosmic

rays or high energy particles. This is a slow and tedious process, and

cannot be used in real time. Recently many improvements in image

detectors for real time observation of microstructural changes have been

made. However, most of these are on indirect detection devices. X-ray

camera are classified as either direct or indirect detection devices.

A direct detection camera detects the electric charge produced when x-rays

strike a photoconductor, while an indirect detection camera detects the

visible light rays produced when x-rays strike a phosphor. The latter

detection scheme is called indirect since the visible light rays must

still strike a photoconductor to produce an electric charge. This scheme

has the disadvantage that the spatial resolution is controlled by the

phosphor thickness, and the sensitivity is controlled by the efficiency

of converting x-rays to visible light rays (typically about 10 percent).

While the sensitivity can be improved by inserting an image intensifier

after the phosphor, this further degrades the spatial resolution. By

comparison, direct detection camera based on the x-ray vidicon tube have

superior spatial resolution but inferior sensitivity. A direct detection

camera based on a charge coupled device (CCD) area sensor should have

spatial resolution comparable to the x-ray vidicon, but much better sensitivity. The resolution is controlled by the CCD photosite size, which is

currently as small as 15 by 15 microns for one commercial area sensor. The sensitivity is controlled mainly by the photosite dark current. Since

the sensor is small, it is practical to cool it to reduce the dark current

enough to detect single x-ray photons. These advantages of spatial

20
resolution, sensitivity, and size promise to make the device useful for NDE

radiography and synchrotron radiation topography.

A CCD image sensor which is being developed in this group has a rectangular

array of square pixels with 490 rows and 328 columns. The pixel dimension,

and the center to center distance between pixels, is 24.4 j:m. Half of the

rows are used for image integration, and the rest for image storage. The

integration period may vary from 1/60 sec to about 10 minutes. At the end

of the integration period, the charge accumulated in the image integration

region is rapidly transferred to the image storage region. During the

next integration period, rows of charge in the storage region are shifted

through the storage region into a serial register, and charge packets in

the serial register are shifted through the serial register to an output

amplifier. The output contains a signal component, a clock component, and

a dark current component. The output is processed to remove the clock and

dark current components, and is converted to a video signal. A commercial

frame grabber stores the video signal, and drives a TV during the integration period. Constructions of the camera is in progress, and comprehensive

tests are planned.

Collaborative Synchrotron Radiation Research: Dental Microradiography

Subtask 5 of Task 15442

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

In collaboration with scientists from American Dental Association Health

Foundation Unit, a technique that is called parallel beam microradiography

with x-ray image magnification [1], [2] has been applied successfully to

the identification of structural details of carious lesions in human

tooth specimens, revealing considerably more structural features of the

lesion than do conventional contact radiographs [3], While conventional

microradiographs show dentinal tubules running parallel to one another,

the present technique reveals a woven structure in which the tubules are indeed oriented in various directions throughout the thickness of the

specimen. Also while the lines of Retzius in a lesion are seen as continuous radiolucent bands in a contact micrograph, the parallel beam

microradiograph with an x-ray magnifier show that each band contains

alternating radiopaque and radiolucent cross striations. In these

parallel beam microradiographs taken with the x-ray magnifier (70X), the

spatial resolution has reached less than 2 urn.

[1] W. J. Boettinger, H. E. Burdette, M. Kuriyama, Rev. Sci. Instr. _50_ 26-30 (1979).

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

Nuclear Instr. & Methods 222 256-258 (1948).

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

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

21
Figure 1 Synchrotron Radiation Topograph of a Bismuth Silicate Single Crystal

This topograph was taken at X-23A, NBS Materials Science Beam Lines at National

Synchrotron Light Source, Brookhaven National Laboratory. Monochromatic (8 Kev)

radiation was prepared by a double asymmetric Si crystal diffraction arrangement

to obtain (930) diffraction in surface reflection from a supposedly perfect bismuth

silicate crystal. The storage ring was operated at 35mA, 2.4 Gev. The sample was supplied by A. R. Tanguay, Jr., University of Southern Califronia.

22
METALLURGICAL PROCESSING

Task 15443

The properties of alloys depend on their processing history. The

objective of this task is to develop measurements and predictive models

to allow prediction of the effects that processing conditions have on alloys. Increased reliability, cost savings, and higher performance of

final products can be expected from the resulting improved control of

metallurgical processing. Moreover, investigations of new metallurgical

phenomena, such as encountered in rapid solidification and diffusioninduced grain boundary migration, may lead to improved types of materials

unobtainable by conventional means. For example, work on this task during

the past year has resulted in the production and investigation of a dramatically new class of materials, called quasicrystals, which do not

obey previously accepted crystallographic restrictions concerning periodicity. This work has sparked intense interest in the scientific community

because of the implications it has for fundamental understanding of

materials and the wide variety of new properties that might be provided.

Solidification effects, solid state transformations, diffusion, interface

processes, and kinetic changes that alloys undergo during their production

into final form are central areas of investigation in this task. These

processes determine the microstructures and compositional distributions

in alloy parts and products, which in turn decide the alloy properties

and performance in use. Advanced processing techniques, such as rapid

solidification, and development of improved methods for control of conventional techniques, such as continuous casting of steel and directional

solidification processes, both are important parts of the solidification

studies. In the solid state processing area, new activities on powder

metallurgy, alloy coarsening, and the effect of diffusion-induced stresses

at grain boundaries and other interfaces have been initiated. Applications

of this work include improving the strength of structural alloys, modification of surface properties for corrosion and wear resistance, and optimizing

fiber-matrix bonding in metal matrix composites.

Strong interactions have been established with industry, universities, and

other government agencies. Visiting scientists from industry and universities

come to NBS to participate in preparation of rapidly solidified alloys

for exploratory research and to collaborate with NBS scientists. Major

studies in this task on quasicrystals and rapid solidification are funded

by the Defense Advanced Research Projects Agency. Powder processing work

on rapidly solidified Al-Fe is supported by the Naval Air Development

Center and studies of stress effects on coarsening in rapidly solidified

alloys by the Office of Naval Research. Measurements and modeling of

convection during directional solidification are being sponsored by the

National Aeronautics and Space Administration. Diffusion-induced grain

boundary migration studies directed toward surface alloying were supported

during the past year by the Army Research Office. Interface studies

for application to metal matrix composites are being funded by the Office

of Naval Research.

23
FY 85 Significant Accomplishments

° A new alloy phase that shows 5-fold Icosahedral symmetry both in its

electron diffraction pattern and in its growth morphology was discovered

as a result of a cooperative program on rapid solidification between

NBS and The Johns Hopkins University. This icosahedral Al-Mn phase

belongs to a new class of materials that are neither crystalline,

since crystallography does not allow periodic crystal lattices with

5-fold symmetry, nor amorphous. These new materials, called quasicrystals, have major implications for scientific understanding of

alloy theory and for producing unusual alloy properties and performance.

0 The conditions under which quasicrystals can be produced were systematically investigated. These materials now have been produced in the

NBS Metals Processing Laboratory by all three major rapid solidification

techniques, melt-spinning, surface melting with subsequent rapid

re-freezing, and atomization, and have been found in a number of

different alloy systems. Importantly, a second quasicrystalline

phase showing decagonal symmetry was discovered at higher Mn concentrations. Moreover, it was found that addition of Si to Al-Mn

suppressed competing phases, such as the decagonal phase, and for the

first time allowed the formation of single phase icosahedral material.

° The effect of container side walls on the convection produced during

directional solidification was analyzed. Usually it has been assumed

that side walls will reduce convection because of forces between the

side walls and the flowing fluid. Surprisingly, it was found that

there are regimes where the presence of side walls will instead

increase alloy convectional instabilities. Thus reducing the distance

between side walls will not help to eliminate convection in those

regimes

° A driving force arising from the effect of diffusion-induced coherency

strains has been identified as responsible both for diffusion-induced

grain boundary migration and for liquid film migration that occurs during liquid phase sintering. Convincing evidence for this conclusion

was found by analyzing experiments in which the migration rates went

to zero when a composition range was selected where the lattice

parameter change with composition was zero. This result has significant

implications for surface alloying to produce protective coatings and

for diffusional interactions at interfaces in composite materials

since it predicts that coherency strains can produce significant

changes in alloy interface compositions.

° Coarsening of the microstructure in rapidly solidified Al-8 wt% Fe

powder was measured. The rate of coarsening depended strongly on the

original powder microstructure, which in turn depended on the original

powder particle size. The slowest, most desirable coarsening regimes were found in alloy samples having the smallest original particle

diameters

24
Rapid Solidification

Subtask 1 of Task 15443

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 provides

a new approach to alloy design which can permit the tailoring of microstructure to meet specific alloy property requirements. To promote the

evolution 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;

(b) the kinetics of microstructure formation; and (c) improvements in

processing techniques used for the production and consolidation of rapidly

solidified alloy particulate.

Quasicrystalline Al-Mn Phases

The recent discovery by guest worker D. Shechtman from The Johns Hopkins

University and scientists at the National Bureau of Standards of new types

of materials, called quasicrystals, which do not obey previously accepted

crystallographic restrictions concerning periodicity has opened up major

new areas of investigation important for our fundamental understanding of

materials. This discovery has generated great interest in the scientific

community, both in the U.S. and abroad. Quasicrystal Al-Mn alloys now have

been produced at NBS by all three major rapid solidification techniques,

melt spinning, surface melting with rapid re-freezing, and atomization.

The current quasicrystal alloys are metastable but do not transform until

heated above 300°C.

One major area of investigation currently underway is analysis of the

crystallography of these new structures. Until quasicrystal alloys were

found, the general wisdom had been that even rapidly solidified alloys

would be either crystalline (with fully periodic structures) or amorphous.

Thus, the discovery of a new phase, that diffracted electrons like a single

crystal with long-range orientational order but had point group symmetry

m35 (icosahedral) , figure 1, which is inconsistent with lattice translations,

was indeed surprising. This phase shows 5-fold symmetry both in its

electron diffraction pattern and in its growth morphology. It has now been

observed in a number of aluminum-transition metal alloys and over a wide

composition range, from 15 to 35 wt% Mn, in rapidly solidified Al-Mn alloys.

The solidification conditions required to form quasicrystals were examined

in detail. Controlled electron beam melting and resolidification experiments were conducted in the NBS Metals Processing Laboratory at scan rates

between 0.1 and 200 cm/s on compositions between 3 and 30 wt% Mn. The

microstructures produced by these experiments are summarized in figure 2.

At compositions of 18 or more wt% Mn, the equilibrium phases are replaced

by quasicrystals in the more rapidly scanned melts. Two types of quasi

crystals are found to grow competitively in these melts; the icosahedral

phase discovered by Shechtman and a phase, labeled T in the figure, which

belongs to another noncrystallographic point group (decagonal). This phase.

25
which is formed by higher Mn concentrations, has a single 10-fold rotation

axis and has translational periodicity along this axis. However, it is

non-periodic in the other two dimensions. The decagonal phase was discovered in collaboration with guest worker L. Bendersky of The Johns

Hopkins University. In the electron beam melts, the decagonal phase

dominated at slower velocities (10 cm/sec) while the icosahedral phase

dominated in the fastest scans (200 cm/sec). The addition of 5 wt% Si to

the alloy suppresses the formation of the decagonal phase and allows the

formation of single-phase icosahedral in an alloy containing 33 wt% Mn.

This recently discovered ability to produce samples that are 100% icosahedral is important for many types of measurements.

X-ray diffraction studies have demonstrated that the icosahedral phase

can exist with a wide range of compositions in the Al-Mn system. However,

the exact arrangement of the atoms in this phase is not known, in spite

of the world-wide research effort that has developed since its initial

announcement. Quasicrystal phases are now being reported with additional

non-crystallographic point groups (an infinite number are possible) and

in other alloy systems, so it is evident that a large new class of

materials has been found.

Kinetics of Microstructure Formation

Experiments have been performed on two alloy systems, Al-Fe and Ag-Cu, to

investigate critical areas where modification of solidification theory is

necessary to predict the microstructure of rapidly solidified alloys.

Rapidly solidified Al-Fe base systems are considered technologically

important because, among other things, fine precipitates which strengthen

the alloy and do not coarsen quickly can be produced in these systems.

The low equilibrium Fe solubility and the metastable extended solubility

produced by rapid solidification are important in this process. Vacuum

atomized powder of Al-8 wt% Fe was examined and found to exhibit four

distinct microstructures whose relative abundance changed greatly with

increasing particle diameter in the size range of 5 pm to 45 pm: microcellular a-Al; cellular r*-Al; a~Al + AlgFe eutectic; and A^Fe primary

intermetallic structure (fig. 3). The importance of initial undercooling

was demonstrated in the small powder particles (~10 pm or less) which

exhibit a two-zone microcellular-cellular structure in individual powder

particles (fig. 4). In the two-zone microstructure, there is a transition

from solidification dominated by internal heat flow (recalescence) and

high growth rates (microcellular) to solidification dominated by external

heat flow and slower growth rates (cellular). The formation of a two-zone

microstructure from an initially cellular structure was unanticipated and

indicates the importance of solute redistribution in preventing free

dendritic growth. Larger particles experience little or no initial

undercooling prior to solidification and do not exhibit the two-zone

structure. The larger particles contain cellular, eutectic, or primary

intermetallic structures that are consistent with coupled zone analysis

and imposed growth rates controlled by heat extraction through the particle

surface (external heat flow).

26
Ag-15 wt% Cu alloys were solidified at controlled rates between 0.1 cm/s

and 18 cm/s using electron beam melting and resolidification to document

the change in cellular microsegregation patterns which occur with increasing

growth rate. The amount of solute incorporated into the cell interiors has

a direct influence on the volume fraction of intercellular phases and the

degree of precipitation (strengthening) which can occur in the cell interiors

during subsequent thermomechanical treatment. The cell spacings for this

range of growth rates are between 2.5 pm and 0.25 u®, respectively, and

the measurement of microsegregation profiles was performed by STEM in

collaboration with L. Bendersky of The Johns Hopkins University. The

average Cu content of the cells increases with increasing solidification

rate at a rate faster than predicted by existing theory. Also the shapes

of the profiles are flat compared to profiles from cells formed at slower

rates. Both of these results suggest potential areas for detailed

theoretical modelling of cellular solidification.

Powder Processing

The effect of consolidation processes on alloy microstructure can be

especially critical for application of rapidly solidified alloys such as high temperature aluminum alloys. These alloys obtain their improved

properties from the fine distribution of precipitate particles that can

be produced during rapid solidification. The rate at which these as- solidified structures change during subsequent consolidation is dictated

by the nucleation, growth, and coarsening of precipitates, and thus,

careful control of the precipitation processes is required.

Figure 3 summarizes the microstructure differences which exist in Al-8 wt%

Fe alloys as a function of powder size. As a result of these microstructural

differences, the microstructural response of different size powder particles

as well as different regions within individual powder particles could vary

significantly under different consolidation conditions. In particular, it

is important to distinguish between the thermal effects and the deformation

effects in the consolidation processes in order to minimize precipitate

coarsening. The coarsening behavior of the various microstructures was

investigated by optical and transmission electron microscopy and precipitate

coarsening data for selected microstructures was obtained. Substantial

variations in precipitate coarsening behavior were observed with the microcellular coarsening rates being the slowest. The activation energy for

volume diffusion computed from the precipitate coarsening data was found

to be consistent with literature values for the diffusion of iron in

aluminum. Based on these results, additional experiments have been started

to investigate the effect of simultaneous application of deformation and

temperature on the as-solidified raicrostructures.

Controlled Solidification

Subtask 2 of Task 15443

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

27
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 have modelled

convection occurring during alloy solidification and cellular interface

morphologies during directional solidification. This predictive modelling

can be used to guide alloy designers in choosing experimental conditions

that will optimize properties of the solidified materials, for example,

in providing homogeneous defect-free material needed for electronic

applications. Ultrasonic techniques are being developed to measure

interface position, velocity, and morphology during the solidification of

steel and other metals. This work is directed toward monitoring of

continuous casting processes to provide real-time feedback and control,

thus aiding in maintaining a uniform product and avoiding catastrophic

breakouts. It also can be regarded as real-time ultrasonic metallography.

Convection during Directional Solidification

During directional solidification of a binary alloy, double-diffusive

convection may occur and cause solute inhomogeneities in the resultant

solid. Our previous two-dimensional time-dependent calculations of doublediffusive convection assumed periodic boundary conditions on the vertical

boundaries. This is a reasonable approximation when the horizontal wavelength of the flow is small compared to the lateral dimensions of the

sample. For the wavelength comparable to the lateral dimensions of the

sample, our numerical algorithm has been modified to use boundary conditions

appropriate for rigid walls. At a rigid wall the fluid velocity and the

solute flux vanish. The boundary condition on the temperature variation

depends on the thermal properties of the boundary, with two limiting

possibilities being vanishing temperature variation (perfectly conducting)

or vanishing heat flux (perfectly insulating). Numerical calculations

indicated that for certain parametric ranges convective instabilities

occurred at lower solutal Rayleigh numbers in the finite system with

rigid walls than in the infinite system with periodic boundary conditions.

This result was unexpected since for a single component system side walls

stabilize the flow.

The linear stability analysis for the directional solidification system

in these ranges is intractable, and a simpler problem has been treated in

order to clarify the role of lateral boundaries in a double diffusive

system. The effect of rigid vertical boundaries on the onset of convective

instability for the salt finger regime of double diffusive convection has

been calculated. The unperturbed state is a quiescent fluid with constant

vertical gradients of temperature and solute, which are stabilizing and

destabilizing, respectively. The horizontal boundaries are stress-free

and perfectly conducting. The lateral boundaries are perfectly insulating

for solute. Changing from thermally insulating to thermally conducting

side walls results in a strong destabilization of the flow for large

thermal Rayleigh numbers even in the limit that the separation between

the side walls approaches infinity. Further, for thermally conducting

side walls, a decrease in the separation of the side walls may destabilize

the system.

28
A series of calculations have been carried out for a model material with

a Schmidt number of unity in order to describe a number of the flow

transitions that can occur during the directional solidification of a binary alloy. Distinct steady states can arise from different initial

conditions for identical values of the processing conditions and materials

properties. In addition, these steady states can transform to time

periodic states.

If the crystal-melt interface is planar and there is no fluid flow in the

melt, then at steady state the solidified material will have a uniform

solute distribution equal to the bulk concentration in the melt. It is

well known that for sufficiently high solute concentrations, a planar

crystal-melt interface will be morphologically unstable, and develop into

a cellular or dendritic interface with lateral solute segregation (microsegregation) . A review of the present theoretical and experimental status

of cellular growth during directional solidification was recently completed

as part of the current work. It appears that the theory is on the verge

of providing a quantitative understanding of cellular growth. Critical

wavelengths predicted by linear stability analysis agree with measured cell

spacings near the onset of instability to within about a factor of two.

For conditions far from the onset of instability, definitive experiments

would provide valuable guidance for theoretical advances. Modern computers

have made possible calculations of nonplanar interface morphologies that

differ significantly from planarity. In collaboration with the NBS

Center for Applied Mathematics, numerical algorithms are being developed

for calculation of three-dimensional solute and temperature fields and

the accompanying interface morphologies. Such calculations will provide

insight into the complex morphologies and transitions which occur during

directional solidification, for example, the occurrence of nodes, elongated

cells, and regular cells for different processing conditions.

Ultrasonic Measurements of Solidification Interfaces in Metals

Ultrasonic techniques are being developed to provide real-time, in-situ , nondestructive measurement of the position, motion, and shape of solidification interfaces in opaque materials. Such a technique would be useful

for feedback and closed-loop process control of solidification to achieve

improved quality control and productivity in continuous casting of steel

or other metals. The technique can be regarded as real-time ultrasonic

metallography

The use of pulse-echo ultrasonic flaw detectors to detect the presence

and location of cracks, voids, and other flaws in metals and non-metals

is well known. The solid-liquid interface in a melting or freezing metal

should also produce a reflected echo, in that there is a measurable

difference in both sound velocity and density across the interface.

Results from the present work have shown that the melting and freezing of

pure iron can be followed satisfactorily by this technique; however, for

304 stainless steel at 1 MHz, weaker signals were obtained resulting from

(1) attenuating effects on beam strength caused by Rayleigh scattering

from enlarged grains produced by rapid grain growth in the solid portion

of the specimen, and (2) weaker reflection from the solid-liquid mushy

29
s?one due to Its more gradual change In acoustical Impedance compared to

the sharp solid-liquid interface for pure iron.

During the past year, a series of measurements on 304 stainless steel and on pure iron was completed, with an improved digital signal processing

system being utilized. In addition, a tungsten-argon arc was used to

establish more planar controlled interfaces. The results showed that the

solid/liquid interface can be followed during both melting and freezing

even in concentrated alloys with substantial mushy zone width, and even

in the presence of substantial bulk beam attenuation due to grain growth

in the solid. A simple optical-type interference theory was proposed to

account for the reduced reflectivity observed from the mushy zone in

concentrated alloys.

Further development of signal processing has proceeded with the assistance

of Professor N. C. Peterson of the Polytechnic Institute of New York.

Software has been written to permit faster averaging to improve signal/noise

ratios in measurements in alloys. This will be particularly important

for practical applications where non-contact transducers, with lower

sensitivities than those that directly contact the metal, must be used to

avoid damage from hot metal contact.

Solid State Processes and Alloy Interfaces

Subtask 3 of Task 15443

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

and S. A. Hackney

Kinetic processes in solids can be strongly affected by interactions

between stress fields and composition gradients. Diffusion processes

modify and in turn are influenced by the forces from these fields and

gradients. Studies have been initiated in this task to investigate these

types of interactions, especially those influenced by interfaces in

alloys. The solid state processes considered here can strongly influence

the microstructure and composition profiles in alloys and hence alloy

properties. Diffusion-induced grain boundary migration may be important

for production of protective coatings , reactions at nonequilibrium interfaces influence bonding in composite materials, and alloy coarsening

strongly affects mechanical properties.

Diffusion-Induced Grain Boundary Migration and Liquid Film Migration

When an alloying element diffuses into a strain-free, chemically homogeneous polycrystal, diffusion theory predicts that solid solutions will

form by a combination of grain boundary diffusion and lattice diffusion.

For fee metals, diffusion is isotropic and concentration profiles that are symmetric across the grain boundaries are thus expected. In contrast

to these expectations, grain boundaries in polycrystals when exposed to a diffusion source have been found to migrate against their radii of curvature

with solid solutions being formed only in the regions swept by the moving

grain boundaries. This recently discovered process, known as diffusioninduced grain boundary migration, has now been found in numerous binary

30
metal systems and provides a new method of surface alloying as well as influencing discontinuous precipitation. When the grain boundary is

replaced by a liquid film, as in liquid phase sintering, the liquid film

can migrate with concomitant alloying under diffusion conditions analogous

to the grain boundary case.

In current work, the driving forces for both grain boundary and liquid film

migration were found to arise from the same source, that is, from coherency

stress. Diffusion of the solute from the grain boundary or the liquid

into the solid creates a stressed diffusion layer if the lattice parameters

of the alloyed and the unalloyed regions are different. Diffusion-induced

migration of liquid films and grain boundaries was analyzed for a variety

of liquid phase sintering systems in cooperation with Professor Duk N. Yoon,

guest scientist from the Korea Advanced Institute of Science and Technology.

By simultaneously changing the concentrations of two solute atoms in liquid

phase sintered Mo-Ni alloys, a perfect lattice matching can be achieved

between the parent grains and the thin diffusion zone, thereby reducing

the coherency strain to zero. In these alloys, it was found that migrations

of grain boundaries within the particles being sintered as well as migration

of the liquid films between neighboring particles ceased at the lattice

matching compositions and increased as one moved away from these compositions.

An analysis of liquid film migration based on the thermodynamics of stressed

solids was developed which explains many features of both diffusion-induced

grain boundary and liquid film migration, including the initiation of

migration, the direction of motion, and the morphology based on the elastic

anisotropy of the dissolving grain alone.

The discontinuous precipitation of liquid droplets at the migrating grain

boundaries induced by temperature decrease has been studied in Mo-Ni and

Co-Cu alloys which have retrograde solidus curves. The solids formed

behind the migrating grain boundaries were found to have the equilibrium

compositions. Recrystallization was found to occur on the grain surfaces

when the liquid matrix of Mo-Ni alloy was replaced by a Cu-Fe melt. A

similar phenomenon occurred when a KC1 single crystal was immersed into

aqueous solutions saturated with KC1 and KBr at room temperature. The

composition analyses showed that the solute concentrations at the migrating

interface decreased because of the increasing length of the diffusion

paths for solute atoms.

Chemical Thermodynamics and Kinetics of Reactions at Non-Equilibrium

Interfaces

The presence of an interface in a system undergoing chemical mixing by

interdiffusion can lead to complex reactions, changes in interfacial

structure during diffusion, and mass transport along and across the

interface not predicted by standard diffusion theory. The most important

issues which are being addressed in our current work are the establishment

of the thermodynamic rules governing interface reactions and the determination of the forces and kinetic effects controlling these various Interface

reactions. Results provided by this work are applicable to a wide range

of interface problems, including matrix-fiber bonding in metal matrix

composites. During the first phase of the study, simple interfaces and

3X
diffusion within single phases in Cu-Mn, Cu-Ni, and Al-Zn systems are being used to isolate the effect of self-stress (stress due to compositional

gradients) on the thermodynamics and kinetics at interfaces. The theory

of the thermodynamics of stressed solids developed in this work predicts

that a compositional discontinuity will exist at interfaces in these

systems as a result of coherency stresses.

Alloy Coarsening

Standard theories of coarsening all assume that the matrix and precipitate

phase behave thermodynamically as fluids, and thus the presence of nonhydrostatic stresses is neglected. As a result, standard coarsening

theory does not describe adequately coarsening phenomena in solids. This

is particularly true in certain precipitation-strengthened alloys where

significant non-hydrostatic stresses exist. In an effort to redress

these deficiencies in our current understanding of ripening phemonena,

work has been undertaken in conjunction with Professor W. C. Johnson of

Carnegie-Mellon University to develop a self-consistent theory of late

stage phase transformation processes in solids. During the course of

this work, examinations have been made of (1) the equilibrium conditions

at the interface of a growing spherical precipitate and (2) the relationship between the interfacial energy of a coherent precipitate and the

mismatch between the precipitate and matrix.

A thermodynamic description of curved solid-solid interfaces has been

used to determine the equilibrium interfacial solute concentrations in

the precipitate and matrix phases in a system consisting of an isolated

spherical precipitate possessing a pure dilational mismatch and different

elastic constants than the matrix. A result of this investigation is

that the equilibrium concentrations at the interface depend strongly on the stress state of the two bulk phases and the interface itself. This

dependence gives rise to a strong coupling between the interfacial

concentrations and the stress generated by the non-uniform composition

field, i.e., the degree of matrix supersaturation, in the matrix. Since

such stresses do not exist in fluids, results for solids will differ

considerably from those given by previous fluid models. In contrast to

fluids, capillarity in a system with a coherent precipitate was found to

depend on both the surface stress, through the surface residual stress

and surface elastic coefficients, and the surface energy. In addition,

the magnitude of the shift in interfacial concentration due to capillarity

was found to depend on the degree of matrix supersaturation.

Using the thermodynamic description of the equilibrium conditions at the

interface of a spherical misfitting precipitate developed above, the

relationship between the precipitate mismatch and surface energy was derived. It was shown that the change in the magnitude of the surface

energy with mismatch depends on the sign of the surface stress and the

surface elastic constants. For example, if the interfacial elastic

constants are small and the surface residual stress is negative, increasing

the mismatch can decrease the surface energy. The ramifications of this

unusual result for Ostwald ripening theory are currently being examined.

32
Figure 1. Selected-area electron diffraction patterns taken from a single

grain of the icosahedral phase. Rotations between 5-fold and the various

2- and 3-fold orientations match the non-crystallographic point group m3 5.

0 10 20 30

Manganese Concentration, wt. %

Figure 2. Mapping of primary phases in electron beam Al-Mn melts of

different velocity and composition. In the icosahedral + T region, the

numbers indicate the relative fraction of the intermetallics which ar< icosahedral, from x-ray intensities.

33
E

a. o

EE E

a, a. a

0 o

CM CO

1 looi I o

Figure 3. Volume fraction of the microcellular, combined cellular and

eutectic, and primary intermetallic structures as a function of powder

diameter of rapidly solidified Al-8 wt% Fe. Possible separate curves for

the cellular and eutectic structures are shown dashed.

Figure 4. TEM micrograph of a Al-8 wt% Fe powder particle. A

single nucleation site (left)

initiates solidification at a high interface rate to produce

a fine cellular structure.

Recalescence slows the interface

rate to produce the coarser

cellular structure at the right.

34
WEAR AND MECHANICAL PROPERTIES

Task 15444

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 com- merically important alloys and coatings.

FY 85 Significant Accomplishments

o Application of the new technique of thermal wave microscopy (TWM) to

the study of wear debris accumulations on sliding contact surfaces

was accomplished. TWM of wear tracks on an oxidized Cu-15 wt.% Zn

alloy showed evidence for periodic density differences in debris

compacts. The presence of such compacts may help explain the differences in the frictional running-in behavior between reversed

sliding and unidirectional sliding. Fabricated specimens with

induced defects also have been examined systematically using TWM.

The data collected indicates that while TWM does reveal the fabricated

defects, other parameters (i.e., sample mounting, shapes, position of

defect in relation to the beam, specimen tilt) play an important

role that needs to be understood.

o Standard reference material 1891, a Co-Cr-Mo material for use with

ASTM F 746, was completed and is now available for monitoring the

corrosion behavior of that and similar synthetic implant alloys.

Corrosion and fatigue data from porous metal coated surgical implant

metals show effects of porous coating production on material properties

and indicate microstructural changes to be avoided during processing

steps on such alloys.

35
o Design and test criteria based on fracture mechanics analysis were developed to establish the basis for constructing seamless pressure

vessels from significantly higher strength steels while maintaining

the same level of safety. Research is continuing to develop valid

criteria for determining the ductility of metals used for pressure

vessels. A technique has been developed for the use of acoustic

emission to periodically inspect large pressure vessels.

o A method has been developed for the quantitative measurement of the

severity of galling wear damage. The method employs topographic

parameters obtained from data acquired by means of an automated profilometer system developed at NBS. The system permits quantitative

assessment of the amount of galling damage, and the results can then

be compared with others using different test methods or involving

other alloys. NBS is recommending a particular standard configuration

for the measurement of galling wear; the matter is now under consideration in the ASTM-G2 Wear and Erosion Committee.

Wear Properties of Metals

Subtask 1 of Task 15444

A. W. Ruff, L. K. Ives, P. J. Blau, J. Harris, C. Olson, P. Boyer, and

E. Whitenton

Friction and Wear of Alloys

The running-in behavior differences between three copper-based alloys

tested under unlubricated sliding conditions were compared. The effects

of direction reversal were of particular interest. The three alloys

(Cu-3.5 wt.% Al, -15 wt.% Sn, and -5 wt.% Sn) were chosen to represent

similar stacking fault energy, single-phase alloys with three different

solute species. In this way, the role of subsurface deformation modes

during sliding could be compared with any differences in sliding friction

and wear behavior. The standard test geometry involved using 52100 alloy

steel bearing balls as the fixed sliders on two computer-controlled traversing stages, one which stroked the surface in one direction then

raised, reset, and repeated, and the other which slid back and forth

without raising the slider. The average friction per stroke was quite

different between unidirectional and reciprocating cases as the surfaces

ran-in. (fig. 1) The nature of the debris distribution and track morphology also differed. The reciprocating cases had much more debris ac- cumulation, and this probably accounted for the friction differences which

were observed. Alloy to alloy differences in both friction and wear

running-in were also observed when testing with the same sliding direction. From these studies it was clear that friction and wear running-in

characteristic depend on both sliding direction and alloy composition.

The effects of oxide films on the running-in friction and wear behavior

of three copper alloys (Cu-3.5 wt.% Al, -5 wt.% Sn, -15 wt.% Sn) tested

in unidirectional and reversed sliding were also investigated. The

standard sliders were 52100 steel balls (unlubricated). Using baseline

36
data from a companion study of the same alloys tested unoxidized, the role

of oxide surface films of about 5.0 /4 m thickness was evaluated.

Aiding in the investigation, a newly acquired thermal wave microscope

(TWM) provided additional insights into the density of debris compacts on

the wear tracks. The use of the TWM represented one of the first applications of this technique to wear debris studies. Using average

track width as a measure of relative wear behavior gave the following

overall ranking of alloys (low to high): Cu-Sn, Cu-Zn, Cu-Al. Differences in friction coefficient were more pronounced than those in wear

rate because friction is more reflective of sliding interfacial conditions whereas the subsurface deformation and fracture properties influence wear. Further work on this project will be directed at modeling

the variations in friction during the running-in period and in microstructurally characterizing the surface film/ substrate interface as it

changes during wear.

Non-destructive testing methods for locating defects in materials, both

near-surface or subsurface, have received increased interest. Thermal

Wave Microscopy (TWM) affords this capability using a pulsed electron

beam in a modififed SEM, to generate thermal/accoustic resonance within

the material. Thermal wave image contrast is affected by thermal

conductivity, microstructural homogenity, and therraoelastic properties

of the materials observed. Practical applications in this area would be

defects in materials relating to inclusions, porosity, and wear.

Galling Wear of Metals

A comprehensive investigation of the process and mechanism of galling of

metals is being conducted under the sponsorship of the Department of

Energy. Galling is a severe form of wear which occurs at sliding surfaces.

Surfaces that have been subjected to galling are markedly roughened as a result of plastic deformation, fracture, and transfer of metal from one surface to the other. The Department of Energy has identified galling as

a significant cause of failure of valves which are employed to control the

flow of gasses and fluids in many energy conversion systems. Roughening

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

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

important aspect of our program has been the development of quantitative

methods to characterize the severity of galling damage. In the past

visual examination had been employed to obtain a qualitative description

of the damage. An automated profilometer system has been constructed

which yields a digitized record of the topography of the galled surface.

Having acquired such a record, parameters descriptive of the surface are then obtained by computer analysis of the data. In addition the measured

topography can be displayed from a perspective that is most useful for

comparison of different specimens. An example of a profilometer tracing

of a galled surface is shown in figure 2. So far, galling mechanism studies

have concentrated on pure metals. Metals having the BCC, FCC and HCP

structures have been examined. Using topographic parameters as the basis

for comparison, it found that damage is most severe in BCC and FCC structures and less so with the HCP structure. HCP cobalt is most notable for

37
its resistance to galling. In the future galling mechanism studies will

focus on alloys. In particular, a series of Cu-Al and Cu-Ge alloys will

be studied in order to determine the effect of stacking fault energy.

This project also involves an Industrial Research Associate from Deere and

Co. A number of machine components employed in agricultural and industrial

equipment are subject to galling damage. There is a need for suitable

design data on the galling behavior of commercial alloys as well as for

test and measurement methods. It is the purpose of this cooperative

program to address some of these problems. During the past year tests

and measurements using NBS methods have been made on several different

steel alloys that are employed in components where galling is an important

design factor.

Wear of Currency Printing Plates

The purpose of this project is to develop methods to improve the wear life

of plates employed by the Bureau of Engraving and Printing to produce U.S.

paper currency. The project is being conducted jointly with members of the

Electrodeposition Group. There are three major objectives; 1) determine

the raechanism(s) 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. All U.S. paper currency

is printed by the intaglio process. A plate with a design in depressed

relief corresponding to the printed image is coated with ink. The plate

is then wiped leaving ink only in depressed areas. Pressing the plate

against the currency paper with sufficient force transfers the remaining

ink to the paper. The plate itself is a replica of an original engraving

made by electroforming. The initial electroformed plate is of a relatively

soft nickel. Without a protective hard surface layer or coating the plate

would have a relatively short service life. Currently a layer of hard

chromium approximately lljLixa thick is electrodeposited onto the nickel.

Based on an investigation of the printing process and an examination of

used plates, we have concluded that the main source of Cr wear is in the

wiping step to remove excess ink from the plate. The ink contains pigments

and certain other solid particulate materials which are used to control

consistency of properties. Some of these particulates or contaminants in

them may abrade the chrome electroplate. In addition the polyvinyl chloride

wiping material contains hard particles which can contribute to the abrasion.

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.

Two laboratory wear test devices have been developed for the study of chrome

electroplate wear under conditions simulating critical aspects of the printing process. The tests have been used to gain insight into the printing

plate wear process and for the evaluation of experimental chrome electro38
plates. Future work on this project will involve the continued analysis

of the wear process as well as the development of test methods and the evaluation of experimental plating materials.

Wear Properties of Metal Coatings

Further studies of micromechanical properties have been carried out on a set of nickel-phosphorous alloy coatings that were previously subjected to

wear measurements. Those results under non-lubricated conditions against

52100 bearing steel showed a difference by a factor of x 16 between the

most and the least wear resistant alloy coating. However, the hardness

difference among the four coatings was only a factor of x 1.2, hence, the

wear difference was ascribed to other factors such as microstructure

differences and intrinsically different wear processes. Studies of these

same alloy coatings have been done on the instrumented microindenter

system (described below) and have revealed several new differences in

mechanical response. Table 1 shows the product of load x displacement for

both worn and unworn coatings, as well as the substrate steel. The microindenter test separates out the elastic (recoverable) material response

and the plastic (nonrecoverable) response. The ratio of these (elastic/

plastic) shown in the table is greatest for the most wear resistant

coating, Ni-5P (electroless). That coating also shows the greatest elastic

response change between unworn and worn condition (1-WE/UWE). These

effects are related to the work-hardening characteristics of the alloy,

and thereby to its wear resistance. The studies are continuing to further

understand this connection.

Mechanical Properties of Metals

Subtask 2 of Task 15444

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

An accurate assessment of the mechanical properties of materials is necessary in order to design and build mechanical components that can be used

under a wide range of loading and environmental conditions. The objectives

of this task are to (1) accurately characterize the mechanical properties

of materials, (2) develop test criteria and test methods for evaluating

the mechanical properties of materials, and (3) demonstrate the applicability of the test criteria and properties for use in the design and evaluation of mechanical components.

Micromechanical Properties

Conventional mechanical tests that are used to measure such properties as strength, ductility, fracture resistance and hardness can not be used reliably to determine the properties of very small bodies such as particles,

thin films, fibers, and coatings and for nonhomogeneous materials such as composites. Therefore, test methods and criteria for characterizing tin*

properties of these materials are needed. One area of the present work is

to identify mechanical properties requirements and develop test methods

39
that can be used to evaluate the mechanical properties of components used

in microelectronic devices and packages. The emphasis on this work is to

improve methods for determining the strength, fracture resistance, ductility and fatigue strength of fine wires and coatings used in microelectronics devices.

Test Methods and Design Criteria for Pressure Vessels

Research and technical assistance is provided to the Office of Hazardous

Materials in the Department of Transportation to develop safety standards

for metallic and composite pressure vessels used in the transportation

of hazardous materials and high pressure gases. During the present year,

design and test criteria have been developed, based on fracture mechanics

technology, to permit the manufacture of seamless steel pressure vessels

from significantly higher strength new steel alloys while maintaining the same level of safety previously obtained with much lower strength steels.

A second project has established acceptance criteria and test methods for

using acoustic emission techniques to periodically inspect large seamless

pressure vessels used to transport compressed gases. Research is continuing to develop valid criteria for determining the ductility of metals

used in the construction of metallic pressure vessels.

Evaluation of Metallic Chimneys

Under the sponsorship of the Consumer Product Safety Commission, extensive

metallurgical and mechanical properties evaluations were undertaken of

metallic chimneys used for wood burning stoves. These types of chimneys

have been associated with numerous house fires and therefore it was required

to determine if degradation of the chimney material during use was a significant cause of the fires. Extensive evaluation was made of chimneys

that had been removed from service and of chimneys that had been tested in

the laboratory under controlled conditions. Chimneys made from AISI type

304 stainless steel did not show significant degradation of the metal

after long terra exposure to flue gas environments in laboratory tests and

after lengthy use in service. Chimneys made from AISI type 430 stainless

steel did not show significant microstructural changes or embrittlement

after extended periods of normal use. Degradation of the properties of

the stainless steel was not identified as a significant cause of the

chimney fires.

Dynamic Microindentation

Facing a wide variety of applications, industrial parts and equipment designers need test methods for measuring dynamic mechanical properties.

A new and nondestructive approach to dynamic mechanical testing is being

developed in this project. Derived from conventional hardness testing

there are two important innovations in this approach. The indentation

is described by the load-displacement curve, and is performed over a wide

range of times, from hours to milliseconds. Recent modifications to the

NBS microindentation tester include a transient digital oscilloscope,

40
improved load and displacement measurements that are now made with respect

to the sample itself (eliminating the need for a compliance correction),

and, a variable duration pause between the test event and residual indentation depth measurement to give a means of determining anelastic

recovery. Table 2 offers preliminary data illustrating the effect of

dynamic loadings for a metal-matrix composite sample. The values report

the loaded condition, and reflect the combined elastic and plastic

deformation response. Explaining the relative softening at the extremes

of load duration requires conjecture. At the slowest rate, creep is a significant factor. At the highest rata, the input of deformation energy

is dissipated as both plastic deformation and local heating. For near

impact conditions, theory predicts about an 80 percent conversion of

the deformation energy into local heating.

Figures 3 a and b report typical test data for a 0-2 hardened and tempered

tool steel. Combining the results for driving into and withdrawing from

the sample, Figure 3b is the load-displacement curve for the indent. Loaddisplacement curves can serve two different functions. First, the deformation energy, the area under the curve, can be partitioned into elastic,

plastic and anelastic components. For example, the total work to indent the

0-2 steel was 430 gf-pm, and 26 percent was elastically recoverable.

Second, the load-displacement and stress-strain curves may be interchangeable. The interchangeability has been already shown for copper, but cannot be generally made. A primary goal of this task is developing a way

to make that general conversion to stress-strain behavior of materials.

Metallic Surgical Implants

Subtask 3 of 15444

A. C. Fraker and J. Harris

Metallurgical aspects of porous metal coatings which are applied to metal

orthopedic devices to support bony ingrowth and provide stabilizaion of the

implant were studied. Continuing work relating to corrosion and mechanical

behavior of surgical implant metals and the production of a standard reference material were carried out. The work planned and conducted is based

on the needs of the implant community which uses approximately 100,000

total hips, 50,000 total knees and 20,000 other joints in the United States

annually. Metals are also used for other needs including heart pacemakers,

heart valves, dental implants and cosmetic purposes. Three important

factors for metals to be used in the body are biocompatibility, corrosion

resistance and mechanical strength. Metallurgical studies are needed to

assure that appropriate materials are chosen and that processing methods

used do not adversely affect the integrity of the material for its intended

use. The nature of this year’s studies was microstructural , electrochemical

and mechanical, and the materials tested were T1-6A1-4V and Co-Cr-Mo alloys.

41
Microstructures of the T1-6A14V porous coated materials revealed effects of

sintering and could be correlated with corrosion-fatigue strength. Sintering above the beta transus lowered the fatigue strength due to the formation of a lamellar grain structure, and sintering, in general, lowered the

fatigue strength to a lesser degree by causing diffusion of oxygen. Some

impurities were found in the arc plasma sprayed porous coatings. Microstructures of sintered porous Co-Cr-Mo coatings were studied and attempts

were made to identify the second phases. Positive identification of these

phases is not easy, and studies in this regard are continuing. Methods

employed in microstructural analyses included light microscopy, scanning

electron microscopy, electron probe microanalysis, x-ray difraction and

microhardness measurements.

Electrochemical measurements were made on the sintered porous Co-Cr-Mo

and arc plasma sprayed porous Ti-6A1-4V. Anodic polarization measurements

were made in physiological saline solution at a pH of 7.4 and a temperature

of 37 C. Results for the porous Co-Cr-Mo materials showed an increase in

current density but no change in the breakdown potential. The results

with the porous Ti-6A1-4V show an increase in current due to the increased

surface area and a lower breakdown potential which probably is caused by

contamination that occurs during the application of the arc plasma sprayed

coating. The breakdown potential of the uncoated Ti-6A1-4V is +2.4 volts

vs. a standard calomel electrode (s.c.e.) and the breakdown potential of

the coated material ranges from +0.7 to +1.2 volts vs. s.c.e.

Mechanical property measurements consisted of corrosion-fatigue tests to

determine the effects of applying porous metal coatings and were conducted

in fully reversible torsion at a frequency of 1 Hz and in flowing physiological saline solution at 37 C. The process of applying Ti-6A1-4V

coatings by arc plasma spraying did not affect the corrosion-fatigue life

adversely. Heat treating the porous coated Ti-6A1-4V materials reduced

the fatigue life due to microstructural changes and contamination.

Microhardness of the coating and the substrate increased after heat

treating. Initial studies of corrosion-fatigue behavior of sintered CoCr-Mo material show a slight decrease in fatigue life. The change is

small and more data are needed before results can be fully analyzed.

Standard Reference Material 1891 was prepared. Sixty units containing two

specimens each of Co-Cr-Mo were delivered to the Office of Standard Reference Materials and are available for use with the ASTM test method F-746

for pitting and crevice corrosion.

42
Figure 1. These two plots compare the break-in friction paths to steady

state for two Cu-based alloys tested in unidirectional sliding

and using similar surface preparation techniques. Compositional

and microstructural reasons for the differences in behavior are

the focus of such studies.

Figure 2. Profile tracing of small section of galled track on Mo specimen.

43
Figure 3 Dynamic results for a 100 gram Knoop indentation

of a hardened and tempered 0-2 tool steel.

(a) Applied load and penetration depth curves versus time.

(b) The load-displacement curve.

Table 1. Load x displacement products for the Ni-P coatings in worn and

unworn condition.

LOAD x DISPLACEMENT [g.jjm]

UNWORN TOTAL ELASTIC PLASTIC EL/PL 1-WP/UWP 1-WE/UWE

0-2 steel 430 89 341 0.261 -0.04 -0.17

Ni-12P(DC) 475 134 341 0.393 0.17 0.22

Ni-5P(DC) 504 178 326 0.546 0.04 0.58

Ni-12P(PP) 430 89 341 0.261 0.13 -0.66

Ni-5P(X) 327 45 282 0.160 0.13 -1.98

WORN

0-2 steel 460 104 356 0.292

Ni-12P(DC) 386 104 282 0.369

Ni-5P(DC) 386 74 312 0.237

Ni-1 2P(PP) 445 148 297 0.498

Ni-5P(X) 379 134 245 0.547

Table 2. A comparison of the Knoop Hardness as a function of the duration

of the applied loading for an aluminum alloy matrix composite.

LOAD DURATION (seconds) 100 10 1 0.1 0.01

KNOOP HARDNESS (kg/mm2

) 80 156 160 147 133

44
CHEMICAL METALLURGY

Task 15445

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 and

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 alloy systems have now been completed and preparations

are underway to issue the evaluated titanium phase diagrams as an ASM

monograph.

A major new effort was initiated during the year to digitize over 1500

binary phase diagrams for the new ASM compendium updating the

compilations of Hansen, Elliott, and Shunk. All of the evaluated

diagrams will be included in this new book together with diagrams from

other sources. When finished, a complete on-line database will be

available with consistent pure element properties, nomenclature,

diagram style and format, and agreement with basic thermodynamic rules

of construction.

The experimental efforts in support of the alloy phase diagram work

continued with emphasis on aluminum-manganese and titanium-aluminum

binary alloys. Recrystallization of the recently discovered

quasicrystalline icosahedral and decagonal phases in rapidly solidified

Al-Mn alloys was studied as part of the evaluation of the metastable

phases in the Al-Mn phase diagram. Additional studies have been

carried out on the single phase field on the titanium rich side of the

Ti-Al system to aid in the interpretation of features observed in

earlier DTA experiments.

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 substantia]

interactions with standards writing organizations such as ASTM.

45
FY 85 Significant Accomplishments

© Graphics programs to provide publication quality diagrams for the

Bulletin of Alloy Phase Diagrams and provide input programs for the

phase diagrams database were made fully operational.

© An inter-phase diagram database has been set up to allow for

efficient searching of the metallurgically important information

embedded in a phase diagram. This subset is extracted by a newly

written program which performs a topological analysis of the curves

in the phase diagram.

© Graphing algorithms to allow isotherms or isopleth color

representation of ternary phase diagrams have been developed.

Algorithms which allow real time translation and rotation of

diagrams on the (b/w) Evans and Sutherland terminal are now

available.

© Theoretical and experimental results in the area of magnetic

particle inspection led to the incorporation into a new military

standard of a new method for using Hall-effect probes to determine

proper magnetization levels for effective inspection.

Alloy Phase Stability

Subtask 1 of Task 15445

L. K. Charlton 1

, R. M. Hayes, D. J. Kahan, A. J. McAlister, J. L.

Murray, C. L. Qualey 1

, H. E. Rubin, J. S. Sims 1

, C. E. Sirofchuck 1, L. J. Swartzendruber, and L. B. Wilkinson

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

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

stability of alloy systems, selected with a view to 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.

46
Swartzendruber for Iron alloys. Thirteen Ti-, seven A1-, and three

Fe-based systems have been assessed this year including: elemental Ti,

Ti-B, -C, -Ca, -Er, -Eu, -Gd, -Mg, -N, -Nd, -0, -Pu, -S, Al-Ag, ~Au,

-Cr, -Hg, -Mn, -Ni, -P , Fe~Cu, -Ni, -Nb. Coverage of the system

includes crystal structures, metastable and constrained equilibria, and

high temperature thermodynamic properties as well as the stable

equilibrium diagrams. Calculations of the phase diagram from

thermodynamic data are carried out using a number of computer programs

available at NBS.

In addition data center staff are responsible for technical editing and

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

prototype database project, the editing and computer graphics for a book, Constitution of Binary Alloys, which is to update the

compilations of Hansen, Elliott, and Shunk.

Major changes have been made in procedures for peer review, editing and

computer graphics for the Bulletin which have greatly increased the

efficiency of the staff. A style Guide for authors has been written

and distributed; it defines thermodynamics, crystallographic and phase

nomemclature as well as standard format for the evaluations. Reviewers

are provided with guidelines for the assessment of the manuscripts.

Procedures for graphics data entry have also been standardized.

Graphics and crystal structure data are now loaded into the on-line

database immediately upon publication of the Bulletin. A backlog of

previously published diagrams is also being revised and loaded to the

database. Technical editing of manuscripts is done by the editor and

associate editor, J. L. Murray and B. Burton, ASM Research Associate.

The prototype user-friendly phase diagrams database of graphical and

numerical information is now complete. Before it can be made

commercially available on-line it must be tested by a small number of

users, revised to their specification and documented. More importantly

the bulk of the data needs to be loaded, a very time-consuming data

entry task.

The digitization of figures for the book, Constitution of Binary Alloys

was undertaken at NBS to take the opportunity to load the database

while providing figures for the book that would otherwise have been

drawn by draftsmen. This is a major effect, involving the digitization

of over 1500 phase diagrams in approximately a four-month period. New

diagrams available through the data program are used, the remainder

coming from standard compilations. The project requires considerable

editing on the part of NBS technical staff, increased support for the

VAX software and hardware, tracking and quality control of phase

diagrams, in addition to the actual data entry. To date 700 diagrams

have been digitized and it is anticipated that camera-ready copy will

be available for the entire collection of diagrams by the end of 1985.

This project represents a major accomplishment of the data center in

several respects. First, a complete on-line database will be

available. Second, the diagrams are mutually consistent in pure element
properties, phase nomenclature, and drawing conventions, a first for

phase diagram compilations. Diagrams are required to "pass” computer

checks for the validity of phase diagram construction. They are also

checked by the editors for violations of basic thermodynamic rules of

construction. As a result, the diagrams being entered are all of

extremely high quality.

Experimental Phase Diagrams

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

the study of the complex recrystallization of the quasicrystalline

icosahedral and decagonal 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

occuring during the process identified 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^Mn^ phase was confirmed and

that of 'AljjMn' established. Certain other features of recent

experimental studies of the system were confirmed. The measured heats

of transformation facilitated modeling of the non-equilibrium phases

and permitted estimates of the true liquidus in this region of the

diagram to be made.

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

strongly suggests that these systems too may contain long lived

metastable phases, and that their presently accepted equilibrium

diagrams are incorrect. Studies of these systems similar in scope to

that of Al-Mn will be undertaken in the coming year.

Expansion of our DTA capability is underway. Equipment is being

acquired which will raise the maximum achievable temperature from

1 200°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

tranformation temperatures in the 600 °C to 2000 °C range, and offer

improved accuracy in the heats of tranformation, as well as expanding

the scope of our work.

The low temperature 'thermal event' observed within the single phase a 0 (ordered hep) field on the Ti-rich side of the Ti-Al binary has been

further studied this year. Earlier work had been done on samples of

low oxygen and nitrogen (0/N) content. Selected samples of relatively

high gas content were studied, and display the same thermal effect,

which suggests ordering at the composition Ti^Al. At this composition,

the effect, a weak one, appears at ~740°C. Mechanical properties

change at this temperature, ductility for example being higher above

740°C. Three independent attempts have been made to associate this

phenomenon with a structural change, via high temperature x-ray,

neutron and electron diffraction. No change was discernable in the

superlattice diffraction peaks between room temperature and 900°C. At

48
present, interstitial ordering is suspected as the cause. A similar

situation is encountered in the a (ordered bcc) field in Fe-rich Fe-Al

alloys. Distinct reversible changes are observed thermally and in

mechanical properties, without structural change detectable by X-ray or neutron diffraction. In this latter case, vacancy ordering is the

likely culprit. The two cases should be thermodynamically similar, and

thermodynamic modeling will be undertaken to assess the validity of

these views.

The experimental staff will be augmented in the coming year by the

arrivals of U. Kattner, a guest worker from the Max Planck Institute

and D. Moffat, an NRC post doctoral fellow from the University of

Wisconsin.

NDE Activities

Subtask 2 of Task 15445

L. J. Swartzendruber

A number of the results obtained previously in the area of magnetic

particle testing have now been incorporated into a new military

standard on magnetic particle inspection, MIL-STD-1 949 , which

supersedes the Air Force document MIL-I-6868E, and the Army document

MIL-M-1 1 472 (actual preparation of the document was funded by AMMRC).

The new standard includes a method for using Hall-effect probes or equivalent to determine proper magnetization levels for effective

inspection. This is possible because we have shown, both theoretically

and experimentally, that the tangential value of the H field at the

surface of the part being inspected is the primary factor which

determines the magnitude of the leakage field from a defect of a given

size. Previously it had been assumed that optimum results would be

obtained when the value of B/H was a maximum, thus making the best

value of applied field very difficult to measure and strongly dependent

on the material under test. Our results have shown that, for the

majority of materials, the optimum applied fields drive the material

well into the saturation region. In this case the material properties

are of secondary importance for determining the optimum applied field.

Correctly instrumented Hall probes can then be used to test for proper

magnetization when using either alternating or direct currents.

Another important factor in improving standards for magnetic particle

inspection is testing of magnetic inks and powders for proper physical

characteristics, including particle size, shape, and magnetic

properties. Current specifications, both in the existing ASTM

document, and in the Military Standard are inadequate in this regard.

Future work will be concerned with improving this area, primarily in

cooperation with the ASTM subcommittee.

In the area of dye penetrant testing we have participated in designing

and conducting a round-robin test of three proposed new ASTM dye

penetrant documents (this was done in cooperation with J.J. Hsia and

49
K.L. Eckerle of the Radiometric Physics Division, Center for Radiation

Research). The round-robin results for one of these draft documents

were considered encouraging enough to warrant submission for

subcommittee balloting. Results for the other two documents, one for

measuring thermal stability and the other for measuring ultraviolet

radiation stability, appeared unacceptable. Improvements of the

techniques spelled out in these two documents and a new round-robin are

in the planning stage. This work has pointed out the considerable

importance for a strong effort at NBS to provide a mechanism for the

calibration of the ultraviolet intensity meters used in NDE and for

providing standards against which the fluorescence of dye penetrants

(and magnetic inks) may be compared.

Because of the potential need for standards and specifications in the

field of Barkhausen noise NDE, an evaluation of this field, its

applications, and possible requirements for specifications and

standards, is being conducted. Although the field of Barkhausen noise

is an old one, serious efforts on NDE applications appear to have

started around 1975 with the design of commercial apparatus by the

Southwest Research Institute in the United States, by the Technical

Research Center in Finland, and by a number of groups in the USSR.

Barkhausen noise analysis on metals using inductive sensors is

basically a surface technique, being most sensitive to material within

approximately 0.3 mm of the surface. A number of studies have shown

that Barkhausen noise from deeper regions in a metal can be observed by

sensing the acoustic emission which accompanies a Barkhausen

discontinuity. This has also been called "magnetomechanical acoustic

emission" and is due to the presence of magnetostriction. Although this

technique is generally less sensitive than the inductive method, it can

be expected to have a number of specialized applications.

Barkhausen noise analysis (BNA) has been shown to be correlated to

various material properties including grain size, hardness, internal

stress, and microstructure. It has also been suggested that BNA could

be used for flaw detection. Besides its evident application in quality

control of magnetic material such as silicon steel and ferrites, one of

the most interesting possibilities for BNA is in automated on-line

testing in a steel mill, heat treating plant, or similar facility.

There appear to be two important areas where NBS might make a contribution to the field of NDE using Barkhausen noise. One is in the area of coil characterization, and the other the provision of reference

materials with well characterized noise spectra which could be useful

for system comparison and calibration.

50
CORROSION AND PROTECTION OF METALS

Task lb A 46 ” ~

The activities in this task are designed to combat the effect of metallic

corrosion, which continues to cause severe economic losses in virtually

all sectors of industrial and government endeavor and also poses a serious

threat to safety and reliability. Our efforts in FY 85 can be divided

into four main areas, namely basic research into the mechanisms of the

major forms of corrosion, many of which remain poorly understood; the

development of measurement techniques, both for laboratory and field use;

the evaluation, organization and dissemination of corrosion data from the

literature, conducted in joint National Association of Corrosion Engineers

(NACE)-NBS Corrosion Data Program; and studies of problems associated with

the disposal of high level nuclear waste in geologic repositories.

The mechanistic studies continued to focus on two forms of localized

corrosion, namely environmentally induced cracking and pitting. The

former centered on stress corrosion cracking (SCC) and hydrogen embrittlement (HE), both of which are delayed failure phenomena which lead to

catastrophic and often unexpected failures in virtually all engineering

alloys. Current examples of SCC include the cracking of austenitic

stainless steels and nickel alloys in nuclear reactors; HE most commonly

occurs in steels, particularly in sulfide bearing media such as those

encountered in sour oil wells. Research on the structure of passive

films, traditionally a major strength at NBS, continued in FY 85. These

thin oxide films are responsible for the excellent corrosion resistance of

materials such as austenitic stainless steels, aluminum and titanium, but

unfortunately they undergo local breakdown in the presence of certain

chemical species, leading to the widespread practical problem of pitting.

In FY 85, the development measurement techniques focused on the corrosion

of steel reinforcing bars in concrete, a major problem in bridges and

highways where salt is used for deicing. Our efforts here are designed to

develop an in-situ technique for measuring the corrosion rates of the

steel in the field. This activity is sponsored by the Federal Highway

Administration. Other ongoing programs involve the use of the linear

polarization method to measure corrosion rates of steel in soil, an activity supported by the American Iron and Steel Institute, and the

development of the electrochemical noise technique to study pitting and

other localized corrosion processes. The latter is also being used in

the nuclear waste program described below.

The Corrosion Data Center, the NBS component of the joint NACE-NBS program, has continued to grow in FY 85. Begun in FY 83, the program was developed in response to the clear need for a central source of reliable,

evaluated data which are essential in the selection of materials to combat

corrosion. Rapid access to the data by means of a central computerized

system is an essential feature of this program. A highlight of this year's

activities was the organization of a Corrosion Data Workshop, in which

representatives of various sectors of industry and government came together

to identify the major needs in corrosion data.

51
A new activity in FY 85 concerns a critical national problem, the disposal

of high level nuclear waste. Beginning in the next decade, waste packages

will be buried at several different geologic sites and will be expected to

maintain their integrity for times much in excess of normal service lifetimes.

Localized corrosion, particularly SCC and pitting, have been identified as

a major threat to the metallic outer containers, and, in view of our expertise in these areas, we have initiated a long term program with the Nuclear

Regulatory Commission to address this complex yet critical set of problems.

Our programs were strengthened during the year by the participation of

several guest workers: T. B Cassagne, The Johns Hopkins University; V. H.

Desai, University of Central Florida; A. J. Forty, University of Warwick,

United Kingdom, and F. Qiu, Fujian Institute of Research on the Structure

of Matter, Peoples Republic of China.

FY 85 Significant Accomplishments

© Substantial progress has been made towards understanding the discontinuous nature of cleavage crack propagation in ductile fee alloys

undergoing transgranular stress corrosion cracking

© Modeling of the chemistry and electrochemistry inside transgranular

cracks has been extended to Cu-Au alloys in chloride solutions. The

results confirm that hydrogen embrittlement can be excluded as a cause

of brittle fracture.

© Portable computer systems have been developed to measure corrosion rates

in the field and are being used to monitor the corrosion of steel reinforcing bars in concrete bridge decks and underground steel piling.

© A Corrosion Data Workshop, organized jointly with the National

Association of Corrosion Engineers (NACE), was attended by approximately fifty corrosion specialists from industry, government, and

academe; the Proceedings will be used to help direct the future

activities of the NACE-NBS Corrosion Data Program.

© Analysis of the statistical properties of the random fluctuations of

the passive current during pit initiation has shown that the process

cannot be modeled by renewal processes or homogeneous Markov chains,

but more complicated stochastic models have to be employed.

Environmentally Induced Cracking

Subtask 1 of Task 1 5^46

Stress Corrosion Cracking

E. N. Pugh, U.

Forty 3, M. J.

Bertocci, T.

Kaufman, and

Cassagne 1

, V.

R.D. Shull.

H. Desai 2

, J. L. Fink, A. J.

12

3

Guest Worker,

Guest Worker,

Guest Worker,

Johns Hopkins University

University of Central Florida

University of Warwick, United Kingdom

52
During FY 85, we continued to concentrate on the transgranular stress

corrosion cracking (SCC) of ductile fee materials. Our studies have

focused on what we consider to be the two primary issues in T-SCC,

firstly, how is a brittle cleavage crack initiated in these ductile materials during T-SCC and, secondly, once initiated, why does it stop. In

the terms of the latter issue, our experimental observations of the T-SCC

fracture surfaces of susceptible alloys, such as a-brass and austenitic

stainless steels, and less susceptible materials, such a high strength

Al-Zn-Mg and pure Cu, have indicated the possible significance of the

cleavage step formation process in arresting a brittle cleavage crack. For

instance, it appears that the cleavage steps, which connect the parallel,

but displaced, cleavage facets on transgranular fracture surfaces are formed by basically different processes; for susceptible alloys, the steps

form by some low energy process such as localized plastic shearing or dissolution, whereas for the less susceptible materials, they form by

higher energy processes such as plastic necking (pure Cu) or secondary

cleavage (Al-Zn-Mg). For the two plastic processes it seems probable that

the velocity of cleavage step formation is much less than that of brittle

cleavage. As a result during brittle crack propagation the unfractured

ligaments (the material which eventually fractures to form cleavage steps)

which are believed to lag behind the main crack front, will lengthen.

Since these ligaments are load bearing and become increasingly so as they

lengthen, their restraining effect will increase as the crack propagates.

Thus, it seems likely that the ligaments will effectively lower the stress

intensity at the crack tip to values insufficient for sustaining cleavage,

thereby arresting the crack. This process is illustrated in figure 1

When the unfractured ligaments reach a critical value, l s , the crack will

propagate, provided "embrittlement" has occurred, until the stress intensity at the crack tip falls below the critical value for cleavage. As

indicated, arrest occurs when the ligament length reaches l a and the

propagation distance Ax, simply equals l a-l 3

.

To pursue the above ideas concerning the role of unfractured ligaments,

we have continued our work on the high purity Al-Zn-Mg aqueous chloride

system. Originally, it was felt that by varying the hardness of the

material, it might be possible to alter the process by which the cleavage

steps are formed and, thereby, affect to some extent the susceptibility

to transgranular cracking. As a result, samples were tested in the

underaged, fully hardened and overaged conditions. For all conditions

transgranular cracking was observed (e.g. figure 2), but the cleavage

steps varied significantly in appearance as suspected. Further work aimed

at understanding these differences in cleavage step appearance and their

importance during crack propagation is underway.

Efforts are also underway to investigate the intergranular stress corrosion

cracking (SCC) of the 7000 series aluminum alloys when exposed to aqueous

NaCl solutions or wet atmospheres. In particular, attempts are being made

to determine whether the fracture in these systems occurs by stress assisted

anodic dissolution or hydrogen embrittlement (HE). The role played by the

MgZn2 precipitate that forms at the grain boundary in these alloys is being

determined by careful analysis of the effect of precipitation on the crack

velocity. Variation of the precipitate size and distribution is being per

53
formed by careful control of the alloy heat treatment and composition. The

width of the precipitation free zone (PFZ) near the grain boundaries is

being monitored , and any grain orientation effect on the crack velocity is

being checked. Several specialized experimental methods (e.g. small angle

scattering, neutron activation and inelastic scattering) are also presently

being evaluated to determine their usefulness in the detection of small

amounts of the metastable aluminum hydride (AlHo) phase. The presence of

this phase will then be checked in the 7000 series aluminum alloys subjected

to the harsh environments mentioned above.

The studies concerning charge and matter transport in cracks, in order to

define the localized chemistry which ultimately is responsible for the

accelerated failure, have continued. Since one of the aims of this work

is to identify cases where transgranular stress corrosion cracking cannot

be attributed to hydrogen embrittlement, the modeling of the crack tip

conditions under discontinuous crack advance was extended to the case of

Cu-Au alloys in acidic chloride solutions. These alloys undergo brittle

fracture which is morphologically quite similar to that of brasses. Open

circuit potential measurements show that if a freshly abraded Cu-Au specimen is rapidly immersed in a ferric chloride solution, an initial steep

transient minimum can be observed, but, since the potential varies rapidly,

the determination of the minimum is uncertain. The modeling calculations,

therefore, have been undertaken to establish what could possibly be the

minimum potential attained at the crack tip at the instant of crack advance.

Even taking "worst case" values for the kinetic parameters involved in the

calculations, the results have conclusively shown that hydrogen discharge

cannot occur in these alloy/solution systems, indicating that brittle fracture mechanisms other than hydrogen embrittlement have to be postulated.

Hydrogen Embrittlement

C. G. Interrante and S. A. Harrison

Industrial users of steels must often employ costly strategies to reduce

the possibility of the occurrence of hydrogen embrittlement. Knowledge of

bulk properties and average stress levels is often not sufficient to predict the damaging effects of hydrogen because local property differences

may enhance embrittlement susceptibility. Work in this area at NBS has

centered on relating the fundamental parameters controlling hydrogenassisted crack growth in structural and pressure vessel steels. The objective 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 hydrogen-assisted cracking, to the driving force (the fugacity of

hydrogen associated with a given metal/environment system) and to the important metallurgical factors, such as hardness and inclusion size, shape, and

orientation. These empirical relationships will be useful in predicting

conditions under which cracking is to be expected. These relations can also be useful in the development of our understanding of the cracking

process. When taken with other information they aid in the development of

theoretical models that describe 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

54
with severe hydrogen-charging environments containing hydrogen sulfide, a common contaminant found in that industry. To date these NBS studies have

included development of methods (and techniques) for: (1) measurement of

permeation of hydrogen in steels; (2) removal of iron sulfides from fracture

surfaces; and (3) automated real-time electric resistance measurement of

crack length; and in cooperation with the University of Notre Dame, a method

for measurement of the effective fugacity of hydrogen in steels and environments of interest to this program.

These methods have been used to study and describe conditions that promote

crack branch formation in steels tested. in high-fugacity environments. An

area of research initiated in FY 84 involves the use of acoustic measurements to supplement the other measurements in developing a better understanding of the cracking process and the mechanism of embrittlement. This

work is being interfaced with other studies being conducted within the

Division in the Nondestructive Characterization Group. Preliminary results

are encouraging. The aim is to characterize the cracking process in more

than one way and then measure the size of each increment of cracking, so as

to gain insight into the nature of the cracking (e.g. its intermittent character: the magnitude of the crack jumps, their location in relation to the

crack front, the microstructural features, etc.) In this way, models can be

developed to describe the process and mechanism of hydrogen-assisted cracking in steels. Real-time, electric resistance crack length measurements

will be used to estimate the rate of strain energy released at the crack

front. Acoustic energy detected over various intervals of time will be

compared with and related to the estimates of the energy released. Using

this information, it will be possible to evaluate whether the magnitude of

the crack extension and of the fracture area associated with each acoustic

emission can be estimated from the acoustic emission alone.

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

for use in these studies. The servo-hydraulic test machine will be use for

precracking of fracture mechanics test specimens and for conducting fracture mechanics tests that require complex loading, such as the J-integral,

constant K, and others. This year, computer codes have been written and

techniques have been developed and implemented for the measurements of

acoustic energy and crack length. Next year, wedge-loaded, fixed displacement tests will be conducted using 2.25 Cr-IMo steel, and with various

partial pressures of H2S in an aqueous acetic acid environment. 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 of Task 15446

E. Escalante and D. E. Mathews

In FY 85, we have continued the application of the linear polarization

method to the measurement of corrosion rates in three diverse practical

cases:

55
Steel Reinforcing Bara In Concrete

This project, sponsored by the Federal Highway Administration, was undertaken in response to the problem of corrosion damage to concrete bridge

decks and overpasses resulting from the use of deicing salts. The specific

objective was to develop a non-destructive test to measure the corrosion of

the steel bars in situ. A portable, battery operated, corrosion measuring

system has now been assembled and applied to laboratory and field measurements. The laboratory data show very good correlation to actual weight

loss, and the system is currently being used to measure corrosion on bridge

decks located in Frederick County, Maryland.

Steel Piling in Soil

The American Iron and Steel Institute has supported this project since 1958.

In FY 85, the first measurements of underground corrosion have been made by

a computerized, portable, battery-operated system capable of performing the

corrosion measurement, collecting data in memory, and calculating the corro- sion rate. This system has been applied to piling located in Turcot Yard,

Canada.

Atmospheric Corrosion of Structural Materials

This project, started in FY 83 as part of a program directed by the Federal

Acid Rain Task Force, was completed in FY 85. Over the past year, attention

was focused on the feasibility of using the three-electrode linear polarization technique to measure rates of atmospheric corrosion. Initial laboratory tests indicated that there are limitations to the method but that

rates of attack on a material in different atmospheres could be determined

on a relative scale. Experiments were then conducted on samples exposed on

our roof site and monitored from the laboratory. It was found very difficult to compensate for IR drop using conventional Wheatstone bridge circuits

or by calculating IR and subtracting it from the potential measurement.

However using a current interrupt technique the corrosion measurement was improved, resulting in better agreement between weight loss measurements

and the electrochemical measurements. Thus it was concluded that the linear

polarization technique is in fact a promising method for this application.

Corrosion Data Center

Subtask 3 of Task 15446

G. M. Ugiansky, U. Bertocci, D. E. Clausen 1

, D. F. Derr, E. Escalante,

M. Marek, E. N. Pugh, and A. C. Van Orden

i NACE Research Associate

The highlight of this year’s activities in the NACE-NBS Corrosion Data

Center was the Corrosion Data Workshop, held June 24-27. This workshop,

sponsored jointly with the Office of Standard Reference Data and NACE,

attracted attendees from industry, academia, and government to discuss

their corrosion data needs and the technology to address those needs.

Issues such as the priority of users needs, quality of corrosion data and

56
how corrosion data will be accessed and used in the future were discussed.

A draft version of a standard format for data taking and database input

was produced and will be submitted to ASTM for possible inclusion in

Committee G1 as a standard format. The results from this workshop will be

published and available to the corrosion community and will be used by the

Corrosion Data Program to help plan future work.

Work continued on the three pilot projects on kinetic data described in

the previous report:

Atmospheric Corrosion

The database for atmospheric corrosion of structural materials was extended

in FY 85 by the inclusion of literature data back to 193^; new data are being added as they become available. This year, the software that generates

the map of corrosion across the United States was modified to allow easier

access and manipulation of the data, and, at the same time, the generation

of graphics has been improved. Through the correlation of the atmospheric

corrosion data and the atmospheric pollution data, preliminary damage

function equations have been developed that allow calculation of corrosion

deterioration from pollution data for the six metals studied.

Localized Corrosion

Software has been developed for graphical display of data for pitting

and crevice corrosion of austenitic stainless steels in aqueous chlorides.

The computer program permits autoscaling and statistical analysis of the

data. The database is also being expanded by incorporation of additional

data from the literature.

Uniform Corrosion

Data from the NACE Corrosion Data Survey is being digitized and entered

into our database. Software has been developed to display these data in

a similar but improved format to that in the Survey; also the file can be

searched by material, environment, concentration, temperature and corrosion

rate, and the data printed in tabular form.

Software has also been developed to represent selected uniform corrosion

data in the form of isocorrosion charts. The program permits the temperature and concentration for any point on the graph to be displayed digitally.

In the area of thermodynamic corrosion data, attention has focussed on developing programs for calculating and plotting Pourbaix diagrams on a personal computer. During FY 85, software was completed to generate high

temperature diagrams using the Criss and Cobble approximation for estimating high temperature thermodynamic properties.

57
Nuclear Waste Disposal

Subtask 4 of Task 15446

C. G. Interrante, U. Bertocci, E. Escalante, S. Harrison, M. Kaufman,

E. N. Pugh, F. CHu 1

, R. D. Shull, and G. M. Ugiansky

1 Guest Worker, Fujian Institute of Research on the Structure of Matter,

Peoples Republic of China.

Two programs on nuclear waste disposal were initiated in FY 85, both

supported by the Nuclear Regulatory Commission (NRC). In April, a program

was begun in support of NRC's High Level Waste Management Program, which

is designed to achieve a permanent solution to the problem of disposing of

nuclear waste generated principally from civilian power plants. The work,

centered in the Corrosion Group, will involve scientists from throughout

the Bureau who will assess information concerned with long-term (300 to

1000 years) performance of the nuclear-waste package that will be enclosed

in a geologic repository. Major problems threatening the integrity of the

package are pitting, stress corrosion cracking, and hydrogen embrittlement,

which are the main thrust of research in the NBS Corrosion Group. While

about twenty percent of the NBS effort is expected to be laboratory work,

the main task will be the evaluation of both data and technical models

(used for extrapolation) being developed by the Department of Energy (DOE);

the evaluated data will enable NRC to provide guidance to DOE on the waste

package portions of the disposal system. The NBS work this fiscal year has

involved familiarization with background literature, attendance of meetings

at NRC and DOE and other meetings, and the establishment of an NBS team of

specialists for our long-term future participation in this program.

The second program, sponsored by NRC's Office of Nuclear Regulatory Research,

deals specifically with pitting corrosion which, as indicated above, is

considered a potential threat to the integrity of the waste package. The

program is concerned with the statistics of pitting. Once a pit is initiated, the mechanisms of its growth are reasonably understood; however, the causes of pit initiation are still obscure. Since pitting is, on the whole,

a rare event, a number of researchers maintain that the phenomenon is a stochastic process, and some statistical models have been recently proposed.

These models assume that the underlying stochastic processes have rather

simple properties, but an experimental check that this is the case has not

been carried out.

In the past year, a statistical analysis of the current fluctuations

observed before pit initiation on Fe-Cr alloys has been completed. The

results have shown that the process cannot be modeled by single renewals

processes or homogeneous Markov chains , but more complicated models have

to be employed. Figure 3* for instance contains plots of the intensity of

the process of breakdown of the passive film for 4 experiments, each one estimated in three different ways. Wide fluctuations with time are evident, indicating that pit initiation cannot be modeled by a simple Poisson

process. This work is being extended to pure iron in chloride-containing

solutions, and the development of adequate statistical models has been

initiated.

58
ax* = r - £s where:

AX* •- Crack advance distance = Length of unfractured ligament before propagation

i * = Length of unfractured ligament after propagation

Figure 1. Schematic illustration depicting the manner in which the unfractured

ligaments are believed to lengthen during' a brittle cleavage event

resulting in crack arrest.

Figure 2. Low magnification secondary electron image of a transgranu 1 a

fracture surface of an overaged Al-Zn-Mg alloy displaying tinbrittle "cleavage-like" appearance.

59
(s/s t u#A<») (t)Y A1ISN31NI (s/sjuoas) (*) y A1ISH31NI

(s/s(u«a») (j)y A1ISN31NI (s/sjueA*) (() Y X1ISN31NI

Figure 3. Intensity plots obtained from four recordings of passive fihn

breakdown, each calculated with three different methods.

60

TIME

(s)

TIME

(j)
ELECTRODEPOSITION (ELECTROCHEMICAL PROCESSING)

Task 15447

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 in this field 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

industry in the United States. (1) Strategic Materials - It has been shown

that coatings have been estimated to provide a 30% savings of imported raw

chromium. Research on coatings of amorphous alloys and nickel chromium

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 167 billion dollars/year.

Research in the use of metallic glass coatings and chromium containing

alloys is in progress. (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 so that the substrate alloy can be optimized for mechanical

properties and surface coatings can be optimized for wear. Studies in this

area are in progress to aid the Bureau of Engraving and Printing with

solving problems they are having in wear of their printing plates.

Electrodeposition is one of the few metals processing techniques that in

principle provides the opportunity to control, on an atomic scale, both

composition and structure of the alloy. This technology has been exploited

for many years without an in-depth understanding of the process both to

apply 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 materials.

Significant progress in this area was made last year in modeling the alloy

deposition process and in developing a new kind of alloy whose composition

is modulated perpendicular to the growth direction.

FY 85 Significant Accomplishments

o Completion of the first stage of a mathematical model of the alloy

deposition process taking into account diffusion migration and convection.

The model is capable of predicting composition of alloys of up to 15

components using pulsed or direct current. The model was tested for the

electrodeposition of Sn-Pb (solder). Future work will focus on the effects

of the substrate on exchange current and on nucleation and growth.

61
o Electrodaposition from a single electrolyte of composition modulated

alloys of copper-nickel and nickel-palladium with layer spacing® as low as

Inm. Comparison made between potent iostatic and galvanostatie deposition

indicated that potentiostatic deposition provided significantly sharper

interfaces.

o Development and production of 150 corrosion step-test Standard Reference

Materials samples were completed and have now been made available to the

automotive industry.

o An automated microhardness system was developed and was shown to be capable, not only of measuring microhardness but also

of yielding information on modulus and ultimate tensile strength.

Modeling of the Deposition Process and Metals Processing

Subtask 1 of 15447

C. R. Beauchamp, D. S. Lashmore, R. R. Oberle, and M. Ratzker

A model using a finite difference technique to solve the one dimensional

diffusion equation for a multicomponent system under forced convection has

been developed for the rotating disk electrode. The purpose of this model

is to predict the composition of the deposit and to provide information on concentration profiles in the electrolyte. This model can easily be

adapted to other convection situations and can be used for both direct

current and pulsed current deposition. The model takes into account

migration and has been tested for electrodeposition of Sn-Pb (solder). A

summary of these results is shown in table 1.

The feasibility of applying the model to predict alloy composition of a nickel-chromium electrolyte is now under investigation. The required

parameters for the execution of the model were measured for nickel using a rotating disk electrode system. The software required to control the

instrumentation responsible for current-potential measurements synchronized

with rotational speed was developed for a microcomputer using the CPM

operating system. In addition, an algorithm for the analysis of the data,

including noise suppression, was implemented. Partial results are shown

in figure 1. Each point represents an experiment, and three experimental

series have been plotted. The equivalent analysis for chromium parameters

is presently under study. In this case, the rotating disk electrode is

replaced by a dropping mercury electrode because of the higher hydrogen

overvoltage of the second system.

Studies on the electrodeposition of modulated alloys of both nickel-copper

and of nickel-palladium are in progress. These have indicated that

conducting electrodeposition (from a single electrolyte) using

potentiostatic control provides a sharper interface than the galvanostatie.

technique discussed in the literature. Layers of pure copper and 98 weight

percent nickel have been made and an optical micrograph of 300nm layers is

shown in figure 2. Magnetic properties of copper-nickel composition

modulated foils made in the electrodeposition group are being investigated,

and some preliminary results will be reported in a conference this Fall.

Material with layer spacings of down to lnm have been produced. These

materials contain many thousands of layers and can be made millimeters

62
thick. An investigation of the mechanical properties and a study of the

structure of the interface by transmission electron microscopy and X-ray

diffraction is in progress.

Research on a nickel -chromium alloy deposition process has indicated that

the corrosion currents for the direct current deposits are considerably

higher than those for the pulsed currents and that a sharp transition

exists for both types of coatings. This result as shown in figure 3

indicates that the passive film undergoes a sharp transition, probably from

crystalline to amorphous at about 12 weight percent chromium and is

consistent with results reported by other investigators on similar alloys.

Applied Research

Subtask 2 of 15447

C. E. Johnson, D. R. Kelley, D. S. Lashmore, and M. Ratzker

An investigation of electrodeposited nickel phosphorus metallic glasses

indicated that their corrosion performance was strongly affected by their

layered structure, shown in figure 4. This layered structure inhibits

pitting because every other layer will always be cathodically protected by

its neighbor so that once a pit is initiated, say at some defect, then

corrosion will proceed laterally. This mechanism is indicated in figure 5

which shows dissolution in concentric circles in an amorphous alloy

containing 12 weight percent phosphorus.

A study of the electrodeposition of engraving plates for the Bureau of

Engraving and Printing (BEP) has been in progress for over a year in

collaboration with Dr. Ruff in the tribology group. The first portion of

this focused on developing technical advice to the BEP to improve control

over the process variables and to improve measurement of properties of

electroformed printing plates. Subsequently the investigation focused on a characterization of abrasive wear of various coating materials under a simulated printing environment. Some of the results of this part of the

investigation are shown in figure 6. A new kind of duplex chromium coating

shown in figure 7 shows particular promise in this simulated environment

and its wear performance is compared with various 'hard' chromium coatings

in figure 8.

Standard Reference Material

Subtask 3 of 15447

H. J. Brown, C. E. Johnson, D. R. Kelley, D. S. Lashmore, S. P. Lewis,

J. L. Mullen, P. N. Sharpless and T. C. VanVechten

The microhardness indentation process involves a sampling of a very small

volume of material in the region of the indentor. The instantaneous values

of hardness and load displacement characteristics provide information

related to microdeformation and contain information related to the elastic

properties and yield strength of the material. This project was designed

to develop the instrumentation to characterize the process and to measure

microindentation characteristics of important alloys. This project made

use of commercially available instruments due to the desirability of

63
rapidly transfering to industry a new technology. The development of this

kind of a NDE technique is particularly important to the electrodeposition

field because of the typically small volumes of material available for the

measurement of mechanical properties. Significant improvements in the

apparatus this last year have resulted in very clean load-displacement

curves, an example of which is shown in figure 9 for very fine grained

polycrystalline copper. The Vickers Hardness Number as a function of

displacement is shown in figure 10 for the same material. From the

unloading portion of this curve it is possible to calculate the Young's

modulus, which was found to be 1,400 Kg/imn (20 million psi), consistent

with the literature values. An estimate of the Ultimate Yield Stress

obtained from the data using a value of 2.9 for the ratio of Vjckers

Hardness to ultimate tensile strength was found to be 46 Kg/mm . (65,320

psi). This value is typical for very fine grain copper. Microhardness

standards have been in production for two years and are selling well.

Research is now in progress to a new very high hardness standard which

should be available sometime next year.

An investigation of two major electrochemical techniques for the

measurement of surface area has been completed. This project was undertaken in order to determine the feasibilty of fabricating surface area

standards. The first of these techniques utilizes a measurement of the

capacitance of the double layer as an indication of the surface area. This

technique was found to be extremely accurate and very sensitive to the

surface roughness. The second technique utilizes a measurement of the

diffusion current, a much more convenient measurement for larger samples.

Using the former technique the specific surface area for the

? NBS

2

"Ultra

Black" electrodeposited coating was found to be about 100 cm /cm . The high

specific surface area coupled with the well known catalytic activity of

nickel oxide for the hydrogen evolution reaction has indicated that this

coating may have application in hydrogen electrolysis. An example of the

diffusion current measurement as a function of surface area is shown in

figure 11.

A new Corrosion Standard (SRM 2350) designed to assist the automotive

industry in assessing the corrosion resistance of electroplated parts has

been completed and has gone into production. The standard consists of two

nickel layers, each of different sulfur content, electrodeposited over a copper layer. The function of this standard is to provide industry with a precise means of calibrating their 'step test' apparatus by providing a physical standard whose properties are well characterized. An example of a graph of electrochemical potential as a function of thickness for one of

these standards is shown in figure 12. A computerized data reduction

scheme has been developed to provide accurate values of potential and

thickness.

2

A new gold thickness standard with a nominal thickness of 2.2 mg/cm was requested by the electronics industry and is now in production. The

electrodeposition group now produces a total of seven different gold on nickel coating thickness standards.

The computer programs used to automatically measure the majority of

nonmagnetic copper on steel coating thickness standards have been revised

by Sharon Lewis to make them easier to use. A large manual has been

written by Fielding Ogburn, Retta Brown, Sharon Lewis, and Carole Derr

64
describing, in detail, the steps necessary to fabricate coating thickness

standards and will be made available to those industries who wish to

prepare their own secondary standards.

A dye penetrant crack standard made with a dull surface has been

evaluated by industry and found to be the most representative material

containing actual fatigue cracks of any crack standard now available.

Table 1. Comparison of computed and experimental results for the

composition of lead in deposits of lead-tin alloys.

Direct.-Current Computed Values Experimental Difference

(ma/cm ) Molar % Pb Results in percent

20 64.6% 45.48% 19.12%

25 51.68 48.89 2.79

30 43.07 50.13 -7.06

35 36.92 39.25 -2.33

40 32.31 37.29 -4.98

Pulsed Current

20 64.98 44.01 20.97

25 52.04 65.00 -12.96

30 43.39 47.54 -4.15

35 37.21 45.5 -8.29

40 32.56 45.89 -13.55

65
OWCS

ION

OJRRFNI

- 7.824

Figure 1. The Log of the current as a function of potential for nickel incorporating

the noise reduction scheme.

Log i

10.0 758.0

14.04

E(mv)

fe

Figure 2. An optical micrograph

of a cross section of a nickel -copper

composition modulated alloy.

Figure 3. The corrosion current measured in

Hank's solution for nickel -chromium alloy as

a function of chromium content, for both direct

and pulsed current deposition.

iO'

1

t in l?

*r r wwin

It 18 7C 66
Figure 4. An optical micrograph

of an etched cross section of

Ni 12% P showing the layered

structure. Unlike the composition

modulated alloys (figure 2) this

material undergoes only about 3-5%

(by weight) variation in composition

from layer to layer.

Figure 5. An optical micrograph of an nickel-phosphorus alloy following the

corrosion measurement. This micrograph

shows the tendency of one layer to

cathodically protect its neighbor.

Figure 6. The wear measured by

weight loss for various coatings

and counterfaces.

Steal Nickel Chromium Phosphorus

4

S. 1.

67 I Worn Material or Coating
Figure 7. An optical micrograph

of an etched cross section of duplex

chromium consisting of a ductile

base layer and a very hard but

mi crocracked surface layer.

10 pm

10.6 um Cr on Fe

12.6 um Cf on Fe

I 1

16 um Cr on Fe

16.6 um Cr on Fe

15 um Cr on Fe

t > t 17.

um 8 E P Cr on Fe

* # 1 CRACK FREE

AVERAGE FOR ALL

4 um Cr on Fe

I e 1

12.6

um BEP Cr on Nl on Fe

I e 1

6 um BEP Cr on Nl on Fe

I • 1

12.6

um BEP Cr on Fe

I • 1

6 um BEP Cr on Fe

10 ~r~

15 20

-8 WEIGHT LOSS / CYCLE xIO g

Figure 8. The wear in weight loss per cycle for many types of chromium.

68
HARDNESS(V)

—I -T- ^

0.0 2.5 5.0

DISPLACEMENT

Figure 9. The load as a function of displacement for copper

using a Vickers diamond indentor.

o

li)

o

N

T 0.0 2.6 5.0

DISPLACEMENT

Figure 10. Vickers hardness(projected area hardness) as a fundi

of displacement. This figure shows 8% strain upon unloading an from this data both modulus and ultimate yield stress can be found

69
Figure 11. The diffusion current as a function of measured surface

area for copper in copper sulfate. The error bars are standard deviations.

MICROMETERS

Figure 12. The electrochemical potential as a function of depth

for a duplex nickel corrosion 'step-test' standard. The point at

which potential measurements are made by the computerized data

reduction system are illustrated by the vertical lines.

70
NONDESTRUCTIVE CHARACTERIZATION

Task 1 5^48

This task is concerned with the development of basic nondestructive

measurement methodologies and their application to both process control

and Nondestructive Evaluation (NDE) . The demand for improvements in

materials performance drives both the development of advanced materials

and quality enhancement (homogeneous optimal microstructures free of

defects) of basic materials. This, in part, is being addressed by the

development of automated materials processing techniques featuring process

control sensors. The juncture of expertise in Nondestructive Evaluation

and materials processing has created the unique opportunity for the

Nondestructive Characterization Group to make significant contributions to

the development of sensors for materials processing. During the past

three years research on sensors has become a major component of the work

of the group. Research has been conducted ( in a collaborative program with

the American Iron and Steel Institute) to develop sensors for a) detecting

porosity /pipe in hot steel ingots and b) for measuring the internal

temperature distributions in solidifying/ solid steel bodies.

Considerable national interest has been shown in this sensor research. One

tangible result of this is an instruction from Congress to develop further

sensors in support of a "leap frog" technology program in the Federal

Laboratories —a new FY 86 initiative. A second tangible result is the

imminent start of a new collaborative program with the Aluminum Association directed at the noncontact measurement of internal temperature

profiles during high speed aluminum extrusion.

As the group's research programs in sensors matures, a new program has

been initiated on interface characterization. Interfaces in general, but

particularly those in composite materials, play a very important role in

determining properties and performance. However, the physical and

mechanical properties of interfaces are notoriously difficult to measure

and thus predictive models relating these quantities to performance are

not verifiable. Partially supported by Strategic Defense Initiative (SDI)

funding, we are exploring techniques for characterizing the interfaces in

metal matrix composites with ultrasonics and acoustic emission.

We have conducted basic measurement science in acoustic emission (an area

in which NBS enjoys a world renowned reputation) and in eddy current

research. For acoustic emission, this has involved research on the

inverse problem and on an approximate calibration technique for commercial

measurement systems (scalar calibration). For eddy current research, the

inverse problem of determining the electrical conductivity depth profile

from eddy current measurements at different frequencies has progressed

well, and a multitude of potential applications are now emerging.

During FY 85 a strong collaborative interaction has continued and includes

a cooperative research agreement with the AISI, steel industry research

associates, cooperative research with The Johns Hopkins University, and

several guest worker collaborations.

71
FY 85 Significant Accomplishments

o Research on an ultrasonic sensor for detecting gross porosity/pipe in

hot steel ingots has been completed, and a prototype system incorporating the NBS approach is undergoing trials at the Argonne National

Laboratory.

o Improved tomographic algorithms for reconstructing internal temperature distributions have been developed and successfully experimentally evaluated on austenitic stainless steel samples at temperatures up

to 750° C.

Noncontact laser/EMAT measurement methodologies for high temperature

ultrasonic sensors have been developed and successfully tested on steel up to 750° C.

o The eddy current inverse problem of determining the depth profile of

the electrical conductivity has been implemented and applied to

laboratory models.

Acoustic Emission in Metallurgy

Subtask 1 of Task 15448

R. B. Clough, J. A. Simmons, and H. N. G. Wadley

If in a solid a defect suddenly grows, elastic waves are emitted. These

waves are known as acoustic emission and by properly analyzing such

acoustic emission signals at one or more locations, one can obtain unique

information about the event. This work on multichannel source characterization attempts to develop the measurement methodologies necessary for

extracting quantitative source information from the emitted signals.

Multichannel Tensor Source Characterization

Studies were made of microcrack propagation in a plate of embrittled 02

tool steel. It was generated by indenting the surface with a Vickers

indenter. Figure la. shows an example of the set of waveforms generated by

the microcrack. The signals were not deconvolved because after the plate

was sectioned, additional large cracks were found. This problem and

others can be eliminated using an in-situ calibration technique which has

been developed. To test the system, indentation microcracks are being

created in soda glass before proceeding to cracking in other brittle

metallic materials (e. g. metal matrix composites).

Scalar Source Characterization

During the past year methods have been developed for scalar calibration of

acoustic emission source strengths. In these methods, a test configuration is stimulated by a series of sources of known strengths (produced, for

example by laser absorption) at the site of the natural source. The ensuing acoustic emission is measured to provide a calibration curve, figure

1b. This curve is then used to deduce the strength of the natural source [1,2]. A significant result found is that the measured energy is approx72
imately independent of the source position, which greatly simplifies

interpretation of data. These calibration methods will be used extensively in future characterization of materials by acoustic emission [

—

5 H

[1] H. N. G. Wadley and R. B. Clough, submitted to Materials Evaluation.

[2] R. B. Clough, submitted to Materials Evaluation.

[3] R. B. Clough, R. J. Schaefer and H. N. G. Wadley, Adv. Mat. Proc.,ed.

H. N. G. Wadley, American Society of Metals, Metals Park, OH, (1985).

[4] Y. Berl insky, H. N. G. Wadley, R. B. Clough, J. A. Simmons and M.

Rosen, Review of Progress in Quantitative Nondestructive Evaluation, ed.

D. 0. Thompson, Plenum Press, NY, Vol.-5, (1986).

[5] H. N. G. Wadley, Review of Progress in Quantitative Nondestructive

Evaluation, ed. D. 0. Thompson .Plenum Press, NY., Vol. 5, (1986).

Eddy Current Conductivity in Metals

Subtask 2 of Task 1 5448

A. H. Kahn, K. R. Long, S. A. Ryckebusch, and L. R. Testardi

It is necessary to develop a theoretical and experimental basis for the

determination of electrical conductivity depth profiles of metallic

materials by eddy current methods. Traditional eddy current testing,

based on a comparison with selective calibration samples, is commonly used

for quality control but samples only some average depth. This research is

aimed at introducing quantitative profiling methods. The methods are generic and may be used for the study of a conductivity profile, no matter

how produced. One area of emerging interest is that of temperature

profiling, since in many materials the conductivity is a unique and

monotonic function of temperature. Discussions with The Aluminum

Association have indicated that such an approach could be very useful for

determining temperature profiles during the extrusion of aluminum. The

Association and the National Bureau of Standards have joined in announcing

the initiation of a Joint Research Associateship to pursue research in

non-contact methods of temperature measurement in FY 86.

The approach to conductivity profiling is based on the depth of penetration of induced eddy currents which varies inversely with the square root

of the excitation frequency. By performing impedance measurements at high

frequencies one can measure the conductivity near the surface. Low frequency measurements reflect the conductivity averaged over varying depths

beneath the surface. The inversion methods under study allow one to con- struct the conductivity profile by unfolding the multi-frequency data [1].

Results of typical impedance measurements and their inversions are shown

in figures 2 and 3 . In figure 3 the solid lines give the step-like

approximation of the reconstruction process; the dashed lines give the

input profile. It is clear that at the present level of operation the

location of a change of conductivity is quite well detected, but the

calculated magnitude of the conductivity change is only qualitative.

Effort is now being applied toward improvement in the computational

algorithms and in the selection of the frequency range of the input data.

73
[1] A. H. Kahn, K. R. Long, S. Rykebusch, T. Hsieh and L. R. Testardi,

Review of Progress in Quantitive Nondestructive Evaluation, ed. D. 0.

Thompson, Plenum Press, NY., Vol. 6, (1986).

Ultrasonics In Metallurgy

Subtask 3 of Task 15448

B. Droney, J. Martinez, J. Cook, F. Mauer, S. Norton, K. Sandstrom, C.

Turner, L. Testardi, T. Hsieh, M. Rosen, B. Elkind, M. Linzer, D. Rogers,

J. Simmons, K. Hershman, and H. N. G. Wadley

Ultrasonic Measurement of Temperature

In 1982, a workshop sponsored jointly by the National Bureau of Standards

(NBS) and the American Iron and Steel Institute (AISI) identified an urgent 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.

Scientists from NBS and AISI are now collaborating to develop methods

based on ultrasonic time of flight (TOF) tomography.

Much of our effort during the past year has gone into consideration of

ways of formulating the temperature-profile reconstruction (tomography)

problem in order to take full advantage of constraints based on the

heat -conduction equation. Because a set of measurements cannot be

completed (by present, manual methods) in a time period that is negligible

compared to the cooling rate, it has also been necessary to include the

time dependence of the TOF explicitly in the formulation. Our approach has

been to express the unknown temperature distribution as an expansion in

the eigenfunctions of the heat-conduction equation. Spatial resolution is

determined by the number of terms retained in the expansion. In general,

numerical ill-conditioning of the inversion problem increases rapidly with

the number of retained terms. Thus, there is a trade off between

resolution and sensitivity to measurement errors. However, heat flow

simulations suggest that, for most metals (which have relatively high

thermal conductivity), higher order terms damp out very quickly.

Reconstructions based on the first term only have been quite successful

and can be estimated from a set of from 4 to 10 TOF measurements by

minimizing the error in a least-squares fashion.

The formulation of the reconstruction problem that has resulted from these

considerations has been tested using data obtained with a manually

operated test rig [1], Ultrasonic pulses were generated by laser

excitation and received by an electromagnetic acoustic transducer (EMAT) so that TOF data could be obtained without making physical contact with

the hot steel. Measurements were carried out on two 304 austenitic

stainless steel bodies, one a 6 inch diameter cylinder and the other a 6

inch square block. Apparatus used for measurements on the square block is

shown schematically in figure 4. The received wave was digitized at 5 ns intervals, and the time of arrival was determined by fitting the leading

edge by linear regression and extrapolating to the baseline. An example

of a reconstruction from ten first-arrival TOF measurements (corrected for

temperature drift between measurements) is shown in figure 5. Thermocouple

74
readings at three points in the block are shown for comparison. Agreement

is within 10° C, which is adequate for most practical purposes and can be

expected to improve when measurements are automated to reduce the effect

of temperature drift.

Meanwhile, components needed for a fully automated system have been

purchased. Software drivers for stepping motors that position beamsteering mirrors have been written. Other software needed for readout of

four waveform digitizers is under development. A schematic drawing of the

automated system is shown in figure 6.

[1] H. N. G. Wadley, F. Mauer , S. Norton and B. Droney, Proc. Roy Soc.

series A (London), 1985 (in press).

Dimensional Resonance Profiling

The search for sensor techniques to be used in steel processing has led to

the discovery of a new method for nondestructive characterization [1].

Combining the simplicity and precision of acoustic dimensional resonance

measurements with the spatial mapping advantage of tomography, the new

method allows one to quantitatively map the variation of the elastic

modulus and density of a material or structure from measurements of only

its resonant frequencies. The technique is physically rooted in the fact

that each different mode pattern of an overtone will sample, and be

affected by, only a single component in the Fourier expansion of the

inhomogeneity. If a number of successive resonant frequencies are excited

and measured, then the inhomogeneity may be recovered by Fourier

summation. The advantages of the dimensional resonance method are that it can utilize narrow bandwidth detection, has its signal enhanced by the

resonant Q, generally utilizes lower frequencies (than pulse-echo

techniques) where attenuation and scattering are less of a problem, and

allows the separation of modulus and density defects for localized

defects. Its largest advantage may be that it is one of the few methods

for mapping spatially broad inhomogeneities in modulus and density.

A complete theoretical analysis of the dimensional resonance problem was carried out for one-dimensional structures [2]. Earlier theory has been

extended to show how both the symmetric and antisymmetric parts of an arbitrary inhomogeneity (corresponding, respectively, to its even and odd

Fourier components) can be recovered by measuring two sets of resonant

frequencies associated with free-free and free-fixed boundary conditions

at the ends of the structure. The more recent theory also includes a second-order analysis of the dimensional resonance problem which provides

an estimate of the error resulting when higher-order terms are neglected

in the first-order theory [3]. We show that under most conditions, when

the material perturbation is small (up to 5 percent of its mean value),

the higher-order contribution can be safely neglected.

Finally, we have obtained, this year, a new result showing that the

thermal diffusivity of a one-dimensional rod can be directly measured by

heating the rod and then observing the change in resonant frequency of the

cooling rod as a function of time [ 3 ]. This latter technique provide::

quantitative diffusivity data while allowing an arbitrary and unknown

75
initial temperature distribution.

[1] L. R. Testardi, S. J. Norton and T. Hsieh, J. Appl. Phys. _56,

2681-2685 (1984).

[2] S. J. Norton and L. R. Testardi, J. Acoust. Soc. Amer. submitted.

[3] L. R. Testardi, S.J. Norton and T. Hsieh, J. Appl. Phys. submitted.

Characterization of the Age Hardening Behavior of 2024 A1 by Resonance

Methods

In Al-Cu alloys, a diffusion controlled- nucleation and growth process

forms precipitates from the supersaturated solid solution. By measuring

the changes in acoustic properties, the effect of the presence of the

precipitates on the elastic moduli may be determined as a function of

aging time and temperature.

The experimental results are shown in figure 7 and figure 8 and are plotted as the change in elastic moduli as a function of aging time. The low

aging temperatures favor nucleation of the precipitates while the higher

aging temperatures favor growth of the precipitates. The aging temperaature also has an effect on the fractional volume of the precipitates in

the matrix. The specimens aged at the lower temperatures will have a higher volume fraction of precipitates relative to those aged at the

higher temperatures. This effect causes the relative change in moduli to

be greater for those samples undergoing aging at the lower temperatures.

Ultrasonic Characterization of Microstructurally Modified Surfaces of

Steels Subjected to Electron-Beam Irradiation

A nondestructive method has been developed for the determination of the

depth and the elastic properties of surface modified layers. Both

parameters can be conveniently observed as variations in velocity with

changes in frequency of Rayleigh surface waves because the waves sample a depth that is frequency dependent. As a test of this technique, studies

were conducted on AISI 1053 plain carbon steel that has been subjected to an electron-beam treatment that created a thin, microstructurally modified

surface layer. On samples with an approximate 1 mm thick rapidly

solidified, martensitic surface layer on a pearlitic substrate, the

Rayleigh velocity varied from 2984 m/s at low frequency (deep penetration

into the substrate) to 2960 m/s at high frequency (penetration confined to

the surface layer): see figure 9. The nondestructive determination of the

layer thickness was found to be 1080ym, compared to 1034pm determined from

metallography

Pipe/Porosity Detection

In the past year, a technique for measuring pipe and porosity in hot steel

has been developed. Ultrasonic inspection with piezoelectric transducers

is a classical approach for the detection of flaws in metals. The

principal technical challenge in the NBS program was to develop a means of

thermally isolating the transducers from the hot steel surface while still

maintaining good acoustic contact with the surface. This is because

76
piezoelectric transducers, such as the ceramic PZT-5A, become depolarized

above their Curie point (-290° C for PZT-5A ) and cease to be piezoelectric. Additional problems inherent in the use of contact transducers are irregularities in the steel surfaces and the presence of surface oxide

(scale). Both of these surface characteristics produce air gaps between

the transducer and steel surface. This in turn can lead to very large

acoustic attenuation and make pipe/porosity signals virtually undetectable.

The NBS approach was to isolate the piezoelectric transducers from the

steel surface with buffer rods which have good mechanical and ultrasonic

transmission properties but lower thermal conductivity, figure 10.

Stainless steel was chosen as the buffer material which best satisfies

these requirements. Good acoustic contact between the steel buffer rods

and steel surface was insured by using a high temperature glass, Borax, as

a couplant. Borax not only melts at a temperature suitable for inspection

of hot steel surfaces (-750° C) but also very effectively fills in the air

gaps between the steel surface and the oxide scale. This ability to

penetrate the scale may well be due to its fluxing properties.

Ultrasonic signals reflected from a 1/4 inch hole side-drilled in a block

of steel with a 4 x 4 inch cross section are shown in figures 11 and 12.

The flaw signals from both the cold and hot steel are seen to be of

comparable amplitude. The feasibility of a pipe/porosity sensor based on

a piezoelectric transducer-buffer rod-liquid couplant configuration has

been established. Emphasis has now shifted to developing, at the Argonne

National Laboratory, a scanning arrangement for field applications.

Ultrasonic Characterization of Interfaces

The characterization of interfaces in metal matrix composites is a new area of investigation. An extensive literature search is underway for

finding interrelations between ultrasonic properties, particularly those

of interfaces waves, and a characterization of the elastic properties in

the vicinity of the interface. Stoneley waves have been generated on a polished contact interface between several aluminum, steel and titanium

alloys to confirm the effect of pressure upon the interface velocity. As

the pressure was increased, the interface velocity also increased,

reaching an asymptotic value which agreed with that of the Stoneley

velocity for the particular pair of materials involved.

A study was also initiated on the effect of incidence angle on the

generation of leaky interface waves both at the interfaces between two

materials and in the so-called ABC sandwich configuration in which a very

thin intermediate layer of material B is interposed between materials A and C. Such waves are more easily generated than pure Stoneley waves, and

the ABC sandwich can be expected to give a better model of real interfaces

in composites where reaction products are always present.

77
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Figure lb. Laser calibration of aluminum alloy plate showing

insensitivity of calibration to source position.

79
Conductivity

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Plots show imaginary vs real parts of impedance (Z)

of a solenoid surrounding the rods. Subscript 0

indicates empty coil.

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Figure 3. Inversion calculations for the data of figure 4.

Solid horizontal lines show computed profile;

dashed lines give the known conductivity. Heavy

vertical lines represent conductive shells.

80
STORAGE

TRANSLATION

Figure 4. Schematic diagram of apparatus for measuring TOF values

in square steel billet.

NORMALIZED DISTANCE

Figure 5. Reconstructed temperature profile for square steel billet

corrected for temperature drift.

81
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Figure 6. Schematic diagram of automated system for measuring

internal temperatures in steel.

82
2500

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Change of Young's modulus 1000 as a function of time for 3o 2024 aluminum alloy.

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Change of shear modulus as

a function of time for 2024

aluminum alloy.

RAYLEIGH VELOCITY vs PENETRATION 0EPTH-IO53 SAMPLE

Figure 9.

Rayleigh surface wave velocity as a function of penetration-depth.

83
Figure 11. Flaw Signal from

Cold Steel

Figure 12. Flaw Signal from

Hot Steel

84
Magnetic Materials

Subtask 6 of Task 15442

L. H. Bennett

A study of eletrodeposited compositionally modulated alloys (CMA) has been

initiated with the Electrodeposition Group, in cooperation with the Naval

Research Laboratory. Alloys with 500 alternating layers of 1.4 nm Cu and

1.4 nm Ni were prepared. This, and similar alloys of 1.6/1 .

nm and

2 . 0 / 2.0 nm were measured by ferromagnetic resonance and magnetic susceptibility. These measurements permit the separation of magnetization from

anisotropy. The results are consistent with a reasonable amplitude of

modulation, and comparable to vapor deposited Cu-Ni CMA.

In collaboration with Dr. R. E. Watson of Brookhaven National Laboratory, two

different applications of results from a new study of the local topology of

atoms in crystals was carried out. The original motivation for the study of

local topology was an inspection of Frank-Kasper phases (topologicallyclose-packed, TCP). These TCP phases were defined almost 30 years ago in

terms of icosahedral and icosahedral-like local topologies: Wigner-Seitz

(i.e., Voronoi) polyhedra are constructed about each atomic site. The TCP

phases are defined as having only coordination number 12 (0,0,12), CN=14

(0,0,12,2), CN=15 (0,0,12,3) or CN=16 (0,0,12,4) polytopes. Frank and

Kasper had difficulty in understanding a Mn which behaved like TCP but

appeared to have unallowed CN13. A recomputation of the Wigner-Seitz cell

for that site found CN=14, but not (0,0,12,2) and therefore was not TCP.

A relation to the magnetic moment distribution in the antiferromagnetic ot Mn

was found from the disclination paths. Detailed study of the crystal

structures and atomic positions for a number of magnetic metals and alloys

with Prof. William B. Pearson of the University of Waterloo, Canada led to

the suggestion of a new relation between magnetism and the topology of the

local atomic environment. It is proposed that there are paths (disclinations)

in the crystal along which essential magnetic exchange coupling occurs, and

that these paths play a role analogous to the superexchange paths which

are important in explaining the magnetism in transition metals salts.

Relations to magnetism have been largely unexplored until now. This procedure is being applied to the technologically important new hard magnetic

material Nd 2 Fei 4

B, as well as to the magnets SmCo5 and Nd2 (Fei_xCox ) i 7 , all of which bear structural resemblance to the Frank-Kasper phases.

The other application of the study of local topology is to the polymorphism

of metallic glasses, discovered earlier (based on NMR, density and EXAFS).

It was shown that there are two distinct local structural glass configurations in Ni-P, whose occurrence depends on the glass processing parameters.

Based on the "quasicrystalline" model, the fundamental building block In

the glass is taken to be the metalloid and its nearest neighbors which are assumed to have the arrangement characteristic of the crystalline system.

Using the Wigner-Seitz construction, it was found that the crystal structures

in transition metal rich Ni-P and related systems fall into two different

topological classes ("triangulated" and "non-triangulated" ) which may account

for the polymorphism in the glasses.

85
RECENT PUBLICATIONS

Bennett, L. H. ; Watson, R. E. Patterns in the occurrence of the brittle

toplogically close-packed phases: A1 in High Temperature Alloys: Theory

and Design. J. 0. Stiegler, ed. The Metallurgical Society of AIME;

103; 1984.

Bennett, L. H. ; Long, G. C. ; Kuriyama, M. ; Goldman, A. I. Local atomic

structure in transition metal/metalloid glasses: Ni-P in structure and

bonding in noncrystalline solids. G. E., Walrafen, ed. 1985; in press.

Bennett, L. H. ; Watson, R. E. Systematics of the alloying behavior of

the noble metals in Noble Metal Alloys. T. B. Massalski, L. H. Bennett,

Y. A. Chang and W. B. Pearson, eds. The Metallurgical Society of AIME;

1984; in press.

Bennett, L. H. ; Watson, R. E.; Pearson, W. B. Topology of local atomic

environments: implications for magnetism and superconductivity.

International Conference on Magnetism; 1985; in press.

Bendersky, L.; Kattamis, T. Z.; Biancaniello , F. S. An analytical TEM

study of new intermetallic phases in the Co-Sn system. MRS fall meeting.

L. H. Bennett; B. C. Giessen; T. B. Massalski, eds. Boston, MA; 82;

1984.

Bendersky, L. A.; Boettinger, W. J. Cellular microsegregation in rapidly

solidified Ag-15 wt% Cu alloys. Proc. of Fifth Inti. Conference on Rapidly

Quenched Metals. S. Steeb; H. Warlimont, eds. Elsevier Science publishers

B. V.; 887; 1985.

Bendersky, L. A.; Boettinger, W. J. Microstructural variations in melt

spun ribbons. Submitted for publication to EMSA, Louisville; 1985.

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. Mat.

Sci.; 1985; in press.

Berlinsky, Y. ; Wadley, H.N.G.; Clough, R. B.; Simmons, J. A.; Rosen, M. Acoustic emission as a nondestructive evaluation technique for

characterizing martensitic transformation. Proc. of Review of Progress in

Quantitative NDE. D. 0. Thompson, ed. Plenum Press, NY; 5; 1985.

Berlinsky, Y. ; Rosen, M; Simmons, J. A.; Wadley, H.N.G. Acoustic

emission: a technique for characterizing the martensitic transformation

in Fe-30wt%Ni. Proc. of Review of Quantitative NDE; 1985; in press.

Bertocci, U. Modelling of crack chemistry in the alpha brass- ammonia

system in embrittlement by the localized crack environment. R. P. Gangloff,

ed. The Met. Soc. of AIME; 49; 1984.

86
Bertocci, U. ; Wagman, D. S. Copper: oxidation reduction protentials

in aqueous solutions. A. T. Bard, J. Jordan, and R. Parson, eds.

M. Dekker, NY; 287; 1985.

Bertocci, U. ; Pugh, E. N. Modelling of potential and concentration profiles

in cracks in Cu alloys. Proc. of the Conference on Corrosion Chemistry

Within Pits, Crevices and Cracks; 1984; in press.

Bertocci, U.; Koike, M. ; Leigh, S.; Qiu, F. ; Yang, G. A statistical

analysis of the fluctuations of the passive current. J. Electrochem.

Soc; 1985; in press.

Blau, P. J. Measurements and interpretations of sliding wear damage in

metals. J. of Tribology; 1985; 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.

Blau, P. J.; Wear testing methods and standardization, ASTM Standardization News; 1985; in press.

Blau, P. J.; Olson, C. D. Some applications of thermal wave microscopy

to research on sliding wear break-in behavior of a Cu-15%Zn alloy in Wear

of Materials 1985. K. C. Ludema, ed. ASME, NY; 424; 1985.

Blau, P. J. Tribology terminology, ASTM Standardization News: 13:

15 ; 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; 1985; in press.

Blau, P. J.; Shives, T. R« Microindentation hardness testing, ASTM

Standardization News; 13: 47; 1985.

Boettinger, W. J. The structure of solid solutions. Metals Handbook;

9th edition; ASM; 1985.

Boettinger, W. J.; Bendersky, L. A.; Early, J. G. An analysis of the

microstructure of Al-8 wt% Fe rapidly solidified powders. Submitted for

publication to Met Trans. A.

Boettinger, W. J.; Coriell, S. R. Microstructure formation in rapidly

solidified alloys. Proc. of NATO Advanced Research Workshop on Rapid

Solidification Technologies. Submitted for publication; 1985.

Boettinger, W. J.; Shechtman, D. ; Kattamis, T. Z. ; Schaefer, R. J. The

effect of rapid solidification velocity on microstructure and phase

solubility extension in NiAl-Cr quasibinary eutectic. Proc. of Fifth

Inti. Conference on Rapidly Quenched Metals. S. Steeb; H. Warlimont,

eds. Elsevier Science Publishers B. V.; 871; 1985.

87
Boettinger, W. J.; Perepezko, J. H. Fundamentals of rapid solidification.

Proceedings of Symposium on Rapidly Solidified Crystalline Alloys; TMS-AIME

1985; in press.

Boettinger, W. J. ; Burdette, H. E.; Kuriyama, M. White beam synchrotron

topography of metals and alloys in Application of X-ray Topographic Methods

to Materials Science. S. Weissmann, ed. 283; 1985.

Bomberger, Jr., H. B,; Meyn, D. A.; Fraker, A. C. Environmental effects

on titanium and its alloys titanium, Science and Technology. Proc. of Fifth

Inti. Conf. on Ti. G. Lutzering, U. Zwicker and W. Bunk, eds. 4: 2435;

1985.

Clough, R. B.; Wadley, H.N.G. Acoustic emission studies of dislocation

motion and microfracture in rapid solidification of A1 and Al-4.5%Cu.

Proc. of Review of Progress in QNDE 4B, Plenum Press, NY; 661; 1985.

Clough, R. B.; Schaefer, R. ; Wadley, H.N.G. Acoustic emission monitoring

of laser drilling in Nondestructive Microstructure Characterization

and Process Control, H.N.G. Wadley, ed. ASM; 1985; in press.

Coble, R. L.; Song, H. ; Brook, R. J.; Handwerker, C. A.; Dynys, J. M. Sintering of MgO and AI 2O3

. Structure and properties of MgO and AI2 O3. Advances in Ceramics. W. D. Kingery, ed. 12: 839; 1985.

Coriell, S. R. ; McFadden, G. B.; Boisvert, R. F. ; Sekerka, R. F. Effect

of a forced Couette flow on coupled convective and morphological

instabilities during unidirectional solidification. J. Cryst. Growth

69: 15; 1984.

Coriell, S. R. ; McFadden, G. B.; Sekerka, R. F. Cellular growth during

directional solidification. Ann. Rev. Mater. Sci. 15: 119; 1985.

Dobbyn, R. C. ; Yoo, K. C. Observation of dislocation images in surface

reflection by synchrotron radiation topography in Applications of X-ray

Topographic Methods to Materials Science. S. Weissman, ed. Plenum, NY;

241; 1985.

Droney, B. E.; Wadley, H.N.G.; Norton, S. J. ; Mauer, F. A. Experiments

with ultrasonic sensors to measure internal temperature distribution.

Proc. of Review of Progress in Quantitative NDE; 1985; in press.

Early, J. G. Recycling ferrous metals. Kirk-Othmer Concise Encyclopedia

of Chemical Technology, Wiley-Interscience; 1985.

Elkind, B. ; Rosen, M. ; Wadley, H.N.G. Ultrasonic characterization of

surface modified layers. Submitted to Met. Trans. A; 1985.

Fang, Q. T.; Glicksman, M. E.; Coriell, S. R. ; McFadden, G. B. ; Boisvert,

R. F. Convective influence on the stability of a cylindrical solid-liquid

interface. J. Fluid Mech. 151: 121; 1985.

88
Frederikse , H.P.R.; Kahn, A. H.; Dragoo, A. L. Electrical resistivity

and microwave transmission of hexagonal boron nitride. J. Amer. Ceram.

Soc. 68 ; 1985.

Gilmore, C. M.; Imam, M. A.; Fraker, A. C.; Yang, S. H.; Van Orden, A. C.

The influence of thermal processing on fatigue crack initiation and

propogation of Ti-4.5Al-5Ma-l ,5Cr. Titanium Science and Technology.

Proc. of Fifth Inti. Conf. on Ti, Vol. 4, G. Lutjering, U. Zwicker, and W.

W. Bunk, eds. 4: 2091; 1985.

Gvishi, M.; Bendersky, L.; Rosen, M„; Wadley, H.N.G. Pre-martensitic

phenomena in equiatomic Ni-Ti alloy. Phi. Mag.; 1985; in press.

Gvishi, M; Rosen, M; Wadley, H.N.G. Acoustic emission characterization

of the martensitic phase transformation in NiTi. Proc. of Review of

Progress in QNDE 48; Plenum Press; 651; 1985.

Hahn, H.; Lare, P. J.; Roure, Jr., R. H.; Fraker, A. C.; Ordway, F.

Mechanical properties and structure of T1-6A1-4V with graded porosity

coatings applied by plasma spraying for use in orthopedic implants,

ASTM Spec. Tech. Pub. 859; 179; 1985.

Handwerker, C. A.; Cahn, J. W.; Yoon, D. N.; Blendell, J. E. The effect

of coherency stress on alloy formation: migration of liquid films in

Diffusion in Solids: Recent Developments. M. A Dayananda; G. E. Murch,

eds. TMS publication. 275; 1985.

Handwerker, C. A.; Cannon, R. M.; Coble, R. L. Final stage sintering of

MgO. Structure and properties of MgO and AI 2O3

. Advances in Ceramics.

W. D. Kingery, ed. 12: 619; 1985.

Hardy, S. C. The surface tension of liquid silicon. J. Cryst. Growth

69: 456, 1984.

Ives, L. K. An extraction replica method for the study of surface films,

ASLE Trans. 28: 87; 1985.

Ives, L. K. ; Peterson, M. B. Effect of solid additives on wear by

greases containing abrasive particles in Wear of Materials 1985.

K. C. Ludema, ed. ASME, NY; 335; 1985.

Ives, L. K.; Peterson, M. B. Models of solid lubrication mechanisms,

in Fundamental of high temperature friction and wear with emphases on solid lubrication for heat engines. Workshop Proc. sponsored by U.S. Army

Research Office, Industrial Tribology Institute, Troy, NY; 43; 1985.

Johnson, W. C.; Voorhees, P. W. Equilibrium solute concentrations

surrounding elastically interacting precipitates. Met. Trans. 16A: 337;

1985.

Kahn, A. H.; Long, K. R.; Ryckebusch, S.; Testardi, L. R. Determination

of electrical conductivity profiles from frequency-sweep eddy current

measurement. Proc. of Review of Progress in Quantitative NDE; 1985; in

press.

89
Kaufman, M. J. ; Fraser, H. L. MIcrostructural analysis of rapid solidification and undercooling in the Al-Ge alloy systems. Proceedings of the

MRS Symposium on Rapidly Solidified Matastable Materials. B. H. Kear,

B. Co Giessen, eds. 28: 335; 1984.

Kaufman, M. J.; Fraser, H. L. The importance of undercooling in the

formation of non-equilibrium structures in the Al-Ge alloy systems.

Into J. Rapid Solidification 1: 27; 1985.

Kaufman, M. J.; Fraser, H. L. Characterization of metastable crystalline

phases in the Al-Ge alloy system. Acta Met. 33: 191; 1985.

Kaufman, M. J.; Stanley, J. T.; Van Aken, D. C.; Field, R. D.; Fraser,

H. L. Microstructure of some rapidly solidified Al-base alloys.

Rapidly Quenched Metals. S. Steeb, H. Warlimont, eds. 941; 1985.

Kaufman, M. J. ; Pugh, E. N. A new approach to improving resistance to

transgranular stress corrosion cracking. Proc. of U.S.A.-Japan seminar

on Critical Issues in Reducing the Corrosion of Steels. H. Leidheiser,

Jr., S. Haruyama, eds. 250; 1985.

Kaufman, M. J. Characterization of stable and metastable phases using

analytical electron microscopy. MRS Symposium on Alloy Phase Diagrams

L. H. Bennett, B. C. Giessen, T. B. Massalski, eds. 62; 1985.

Kelley, D. R; Johnson, C. E.; Lashmore, D. S. Development of microhardness standards, LabCon West, San Mateo, CA; 1985; in press.

Kuriyama, M. ; Boettinger, W. J. Asymmetric crystal topography with

x-ray image magnification in Applications of X-ray Topographic Methods

to Materials Science. S. Weissmann, ed. Plenum, NY; 23; 1985.

Kuriyama, M. ; Long, G. G. Extinction theory in x-ray topography in

Applications of X-ray Topographic Methods to Materials Science.

S. Weissman, ed. Plenum, NY; 97; 1985.

Kuriyama, M. ; Long, G. G„; Bendersky, L. Unit cell structure of rapidly

cooled Al-Mn alloys with icosahedral symmetry. Phys Rev. Lett. 55:

849 ; 1985 .

Lashmore, D. L. Plating on aluminum: a review. Plating and Surface

Finishing. 72: 36, 1985.

Lashmore, D. L. Electrodeposition of nickel chromium alloys. Proc.

of Interfinish '84, Jerusalem, Israel; 1984; in press.

Lashmore, D. S. Pulsed Electrodeposition of nickel-chromium. Proc.

Surface Finishing 85, Detroit, MI.; 1985; in press

Lichter, B. D. ; Cassagne, T. B. ; Flanagan, W. F. ; Pugh, E. N. Studies

of transgranular stress corrosion cracking in copper gold. Microstructural Science 13: 361; 1985.

90
Linzer, M. ; Droney, B. E.; Martinez, J. W.; Mauer, F. ; Norton, S. J.;

Wadley, H.N.G. Progress in development of ultrasonic sensors for monitoring

hot steel product. Proc. of the Fifth Process Technology Division

Conference; 163; 1985.

Long, G. G.; Revez, A. G. ; Kuriyama, M. X-ray absorption study of

tantalum oxide films on silicon. J. Non-crystalline Solids 70: 271;

1985.

Low, S. R. ; Early, J. G. Drop-weight testing of non-standard specimen

geometries. Am. Soc. Testing Materials Spec. Tech. Pub.; 1985; in press.

Mehrabian, R. ; Wadley, H.N.G. Sensor needs for materials processing.

Proc. of Review of Progress in QNDE 4B; Plenum Press, NY; 839; 1985.

Melmed , A. J.; Twigg, M. E.; Klein, R. ; Kaufman, M. J.; Fraser, H. L.

The complementary use of atom probe field ion microscopy and analytical

transmission electron microscopy for the study of a Ni-base superalloy.

J. de Physique, Colloque C9, Supplement au n°12. Tome 45: C9; 1984.

McAlister, A. J. ; Murray, J. L. The Al-Ge system. Bulletin of Alloy

Phase Diagrams 5(4): 341; 1984.

McAlister, A. J. The Al-Sb system. Bulletin of Alloy Phase Diagrams

5(5): 462; 1984.

McAlister, A. J. The Al-As system. Bulletin of Alloy Phase Diagrams

5(6): 577; 1984.

McAlister, A. J. The Al-Hg system. Bulletin of Alloy Phase Diagrams

6(3): 219; 1984.

McAlister, A. J. The Al-P system. Bulletin of Alloy Phase Diagrams;

1985; in press.

McAlister, A. J. The Al-Pd system. Bulletin of Alloy Phase Diagrams;

1985; in press.

McAlister, A. J. ; Shull, R. D.; Reno, R. C. Phase equilibrium in the

titanium-aluminum system. Titanium '84 Science and Technology. North

Holland Publishing Co., New York, NY; 1985; in press.

McFadden, G. B.; Coriell, S. R. Nonplanar interface morphologies during

unidirectional solidification of a binary alloy. Physica D 12D: 253;

1984.

McFadden, G. B.; Rehm, R. G. ; Coriell, S. R. ; Chuck, W. ; Morrish, K. A.

Thermosolutal convection during directional solidification. Met. Trans.

A 15A: 2125; 1984.

McFadden, G. B.; Coriell, S. R. ; Boisvert, R. F. ; Glicksman, M. K.; Fang,

Q. T. Morphological stability in the presence of fluid flow in the melt . Met. Trans. A 15A: 2117; 1984.

91
Mullen, J. L.; Lashmore, D. S. The automation of microhardness measurements.

Proc. of the 40th MFPG Conference. 1985; in press.

Murray, J. L. The Al-Cu system. Inter. Met . Rev. 1985; in press.

Murray, J. L. The Bi-Ti system. Bulletin of Alloy Phase Diagrams

5(6): 610; 1984.

Murray, J. L. The Pb-Ti system. Bulletin of Alloy Phase Diagrams

5(6): 613; 1984.

Neyab-Hashemi , A. A.; Clark, J. B.; Swartzendruber , L. J. The Fe-Mg

system. Bulletin of Alloy Phase Diagrams 6(3): 235; 1985.

Norton, S. J.; Linzer, M. Reconstructing a spatially-incoherent random

source in the near field: exact inversion formulas for circular and

spherical arrays. J. Acoust. Soc. Amer. 26(6): 1731; 1984.

Norton, S. J.; Testardi, L. R. Reconstruction of one-dimensional

inhomogeneities in elastic modulus and density from measurements of

acoustic resonances. Proc. of the 14th International Symposium

on Acoustical Imaging. 1985; in press.

Norton, S. J. Iterative reconstruction techniques: convergence as a function of spatial frequency. J. Opt. Soc. Amer. A 2: 6; 1985.

Norton, S. J.; Testardi, L. R. Reconstruction of one-dimensional

inhomogeneities in elastic modulus and density using acoustic dimensional

resonances. Submitted to J. Acoust. Soc. Amer.

Norton, S. J.; Wadley, H.N.G. Tomographic reconstruction of internal

temperature. Proc. of Review of Progress in QNDE 3A; Plenum Press,

NY; 309; 1985.

Okamoton, N. ; Massalski, T. B.; Swartzendruber, L. J. ; Beck, P. A. The

Au-Fe system. Bulletin of Alloy Phase Diagrams 5(6): 592; 1984.

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. 1985; in press.

Patterson, D. E.; Hujar, R. B.; Escalante, E. Bronze, zinc, aluminum,

galvanized steel: corrosion rates as a function of space and time over

the United States. Proc. Symposium on Degradation of Materials Due to

Acid Rain. Amer. Chera. Soc. 1985; in press.

Paul, E.; Swartzendruber, L. J. The Fe-Nb system. Bulletin of Alloy

Phase Diagrams. 1985; in press.

Peterson, M. B.; Bhansali, K. J.; Whitenton, E. P.; Ives, L. K. Galling

wear of metals in Wear of Metals 1985. K. C. Ludema, ed. ASME, NY;

293; 1985.

92
Pugh, E. N. Progress towards understanding the stress corrosion problem.

Corrosion 41: 517; 1985.

Rogers, C. D.; Droney, B. E.; Toth, J. M.; Wadlev, H.N.G. Detection of

pipe and porosity in hot steel slabs, blooms and billets. Proc. of

26th Mechanical Working and Steel Processing Conf.; 1984; in press.

Rosen, M.; Ives, L. K. ; Ridder, S.; Biancaniello , F.; Mehrabian, R.

Correlation between ultrasonic and hardness measurements in aged 2024

aluminum alloy. Materials Sci. & Eng.; 1985; in press.

Ruff, A. W. Analysis of interlaboratory test results of solid particle

impingment erosion in Wear of Metals 1985. K. C. Ludema, ed. ASME, NY;

1985; in press.

Ruff, A. W.; Polvani, R. S. Micropenetration testing: Characterizaiton

of surface properties of materials involving wear. Surface Technology

BAM; Berlin; 1985.

Shechtraan, D.; Schaefer, R. J.; Biancaniello, F. S. Precipitation in

rapidly solidified Al-Mn alloys. Met. Trans. 15A: 1987; 1984.

Schaefer, R. J.; Coriell, S. R. Convection-induced distortion of a solid-liquid interface. Met. Trans. 15A: 2109; 1984.

Schaefer, R. J. Principles underlying coatings and surface modification

science. Mater. Sci. & Eng. 70: 1985.

Schaefer, R. J, Ion-beam and laser-induced surface modifications.

Mater. Sci. & Eng. 70: 1985.

Shull, R. D.; McAlister, A. J. ; Reno, R. C. Phase equilibria in the

titanium-aluminum system. Titanium Science and Technology. G. Lutjering,

II. Zwicker, and W. Bank, eds. Pub. by Deutsche Gesellschaft fur Metallkunde,

e.v. 1459; 1985.

Shull, R. D.; Kaufman, M. J. Nature of large Ti4Cu20 particles formed

during annealing of Cu55 Ti 45 metallic glass ribbons. Met. Trans. A;

1985; in press.

Simmons, J. A. New method for deconvolution and signature analysis of

causal and transient time series—I. Root transforms and causal boundary

roots. Submitted to IEEE Trans. ASSP.

Simmons, J. A. New method for deconvolution and signature analysis of

causal and transient time series—II. Root projection. Submitted to

IEEE Trans. ASSP.

Simmons, J. A. New method for deconvolution and signature analysis of

causal and transient time series—III. Deconvolution. Submitted to

IEEE Trans. ASSP.

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Singhal, So P.; Biancaniello , F. S.; Alperin, H„ A.; Herman, H. Smallangle neutron scattering study of phase decomposition in the Ni-rich side

of the Ni-N^Al miscibility gap. Scripta Met. 19: 133; 1985.

Smith, J. J.; Friant, C. L.; Rosen, M.; Wadley, H.N.G. Nondestructive

characterization of rapidly solidified alloys in Nondestructive Microstructure Characterization and Process Control. H.N.G. Wadley, ed.

ASM; 1985; in press.

Swartzendruber , L. J.; Shechtman, D.; Bendersky, L.; Cahn, J. W. Nuclear

y-ray resonance observations in an aluminum-based icosahedral quasicrystal. Physical Review B 33: 1382; 1985.

Swartzendruber, L. J. The Ag-Fe system. Bulletin of Alloy Phase Diagrams

5(6): 560; 1984.

Swartzendruber, L. J. The Fe-Rh system. Bulletin of Alloy Phase Diagrams

5(5): 456; 1984.

Swartzendruber, L. J.; Paul, E. The Fe-Ta (iron- tantalum) system.

Bulletin of Alloy Phase Diagrams; 1985; in press.

Swartzendruber, L. J.; Itkin, V. P.; Alcock, C. B. The Fe-Ni system.

Bulletin of Alloy Phase Diagrams; 1985; in press.

Swartzendruber, L. J. Thermodynamic assessment of the iron noble-metal

equilibrium diagrams. AIME Conference Proc.; New York, NY; 1985;

in press.

Takagi, S; Chow, L. C.; Brown, W. E.; Dobbyn, R. C.; Kuriyama, M.

Application of an x-ray image magnifier to the microradiography of dental

specimens. J. Dental Res. 64: 866; 1985.

Testardi, L. R. ; Norton, S. J.; Hsieh, T. Determination of inhomogeneities

of elastic modulus and density for one-dimensional structures using

acoustic dimensional resonances. J. Appl. Phys. 56(10): 2681; 1984.

Testardi, L. R. ; Norton, S. J. ; Hsieh, T. Acoustical dimensional

resonance tomography: some examples in one-dimensional systems.

Submitted to Appl. Phys.

Twigg, M. E.; Melmed, A. J.; Klein, R. ; Kauman, M. J.; Fraser, H. L.

A raicroanalytical study of secondary precipitation in RSR143 using atom

probe field ion microscopy and analytical transmission electron microscopy.

Proc. of Fifth Int. Conf. on superalloys. M. Gell, C. S. Kortovich,

R. H. Bricknell, W. B. Kent, J. F. Radavich, eds. 631; 1984.

Van Orden, A. C; Ugiansky, G. M.; Rodriquez, M. J.; Escalante, E.

Computer assisted corrosion data evaluation and dissemination in Proc.

of the Symposium on Computer Aided Acquisition and Analysis of Corrosion

Data. M. W. Kendig, U. Bertocci, J. E. Strutt, eds. 181; 1984.

94
Voorhees, P. W.; Glicksman, M. E. Thermal measurement of Ostwald ripening

kinetics in partially crystallized mixtures. J. Cryst. Growth; 1985; in

press.

Voorhees, P. W. The theory of Ostwald ripening. J. Stat. Phys. 38: 231;

1985.

Voorhees, P. W.; Johnson, W. C. ; Laraia, V. J. Elastic effects during

late stage phase transformations. Proc. of the Inti. Seminar on soluteDefect Interaction: Theory and Experiment; 1985; in press.

Wadley, H.N.G.; Norton, S. J.; Mauer, F. ; Droney, B. Ultrasonic measurement of internal temperature distribution. Proceedings of the Royal

Society of London; 1985; in press.

Wadley, H.N.G.; Mehrabian, R. Acoustic emission for materials processing:

a review. Materials Science and Engineering 65: 245; 1984.

Wadley, H.N.G. Acoustic emission: natures ultrasound. Proceeding of

Review of Quantitative NDE; 1985; in press.

Wadley, H.N.G; Norton, S. J.; Mauer, F; . Droney, B. Proceedings of

Royal Soc., Series A; 1985; in press.

Watson, R. E.; Bennett, L. H. Optimized predictions for heats or formation

of transition-metal alloys II, CALPHAD 8: 307; 1984.

Watson, R. E.; Sternheimer, R. M. ; Bennett, L. H. Trends in the electric

quadrupole fields at dilute impurity sites in transition metal-transition

metal alloys. Phys. Rev. B 30: 5209; 1984.

Watson, R. E.; Bennett, L. H. The physical modelling of transition metal

alloying: the roles that different levels of theory play in High Temperature

Alloys: Theory and Design. J. 0. Stiegler, ed. The Metallurgical Society

of AIME; 145; 1984.

Watson, R. E.; Bennett, L. H. The quasicrystalline structures of transition

metal/metalloid glasses. International Conference on Magnetism; 1985; in press.

Watson, R. E.; Bennett, L. H. The noble metals as incipient transition

elements in Noble Metal Alloys. T. B. Massalski, L. H. Bennett, Y. A. Chang,

and W. B. Pearson, eds. The Metallurgical Society of AIME; 1984; 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 symposium; ASM annual

meeting; Detroit; 1984; in press.

95
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 1985, 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:

INDUSTRIAL

1. The Aluminum Association

A new collaborative program with the Aluminum Association directed

at the noncontact measurement of internal temperature profiles during

high speed aluminum extrusion is being started in the Nondestructive

Characterization Group.

2. American Cyanamid Corporation

The American Cyanamid Company is sponsoring a Research Associate

position at NBS dealing with electrodeposited metal matrix composites.

3. The American Electroplaters Society (AES)

The AES has sponsored for several years a program in the Electrodeposition Group dealing with the electrodeposition of heat and

corrosion resistant alloys. A new program will start in FY 86

involving the development of a computer model to predict the com- position of binary and higher order alloys under both direct and

pulsed current conditions.

4. American Iron and Steel Institute.

During FY 85 a strong collaborative interaction has continued on

the development of process control sensors for steel. Under a cooperative research agreement with the AISI, steel industry Research

Associates J. Martinez (AISI), B. Droney (Bethlehem Steel),

D. Rogers (U.S. Steel), J. Cook (Armco), and T. Shelenberger

(Inland Steel) have obtained significant new results.

96
5. 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. Three category editors of the program

are working at NBS: J. L. Murray, L. J. Swart zendruber and

A. J. McAlister, for Ti-, A1-, and Fe- alloys, respectively.

6. Artech Corp.

Mr. Henry Hahn, President of Artech, 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.

7. Automotive Industry (Chrysler, Ford, General Motors)

The Electrodeposition Group in response to requests from the

automotive industry has developed a Step-Test Corrosion standard.

Our interaction with these companies has been through visits to

NBS by several of their representatives through ASTM and through

direct round robin tests of our standards.

8. CEM Corporation

The Electrodeposition Group has cooperated with the CEM Corporation

(Lois Jassie) in the development of a microwave thermocouple.

9. COMSAT Laboratories

Several members of the Corrosion Group interacted with scientists

from COMSAT Laboratories in a study of the effects of cathodically

generated hydrogen on the mechanical behavior of a nickel base

alloy, a problem related to the performance of a component of a communication satellite. Slow strain rate tests at NBS under

simulated service conditions demonstrated that the alloy can undergo

significant embrittlement and indicated the range of expected

crack velocities.

10.

The Construction Industries Manufactures Association (CIMA) and

the Farm and Industrial Equipment Institute (FIMI)

A workshop co-sponsored by Argonne National Laboratories ( ANL)

CIMA, and FIMI was held at ANL in March 1985 for the purpose of

evaluating the federal research areas of greatest interest to the

U.S. off-road machinery manufacturers. A series of panels re- presenting industrial and federal organizations identified several

key technologies including tribology (wear and friction) where

97
government research was of interest to industry. P. J. Blau (NBS)

described the wear and friction activities in the ISME, and specifically, in the Metallurgy Division. ANL personnel are following up on the workshop to identify possible federal laboratory/ industrial joint

efforts in the key areas.

11. Deere and Company

A Research Associate Program with Deere and Co. (L. K. Ives, NBS,

and P. A. Swanson, Deere and Co.) 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.

12. DePuy Mfg. Co. , Inc.

Mr. Todd Smith of DePuy has cooperated with A. C. Fraker, NBS,

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.

13. C. S. Draper Laboratory, Inc.

Studies are underway involving the microstructural design of

beryllium, specifically, the dimensional instability, time dependent

shape distortion, and coefficient of thermal expansion. These factors

critically determine the navigational precision of inertial

guidance instruments that use beryllium alloy components. This is

a collaboration among K. Kaplesh and J. McCarthy (Draper) and

R. Polvani (Metallurgy Division). Draper has supplied the materials,

fabricated the test samples and provided funding. NBS will provide

the special measurement capability and interpretation of the data.

14. DuPont Corporation

In cooperation with the DuPont Corp. , the Electrodeposition Group has

developed a new coating thickness SRM. A group of companies (Biddle

Instruments, Magna Flux, Duke Power Company, Pullman Sheet Metal

Works, and Frank J. Koch Inc.) have requested two new coating

thickness SRM’s which have been produced and are now in the FY 85

catalog.

15. FIBA, Inc. and Union Carbide Corporation

A collaborative effort is under way betwen J. H. Smith of NBS and

FIBA, Inc. (Mr. P. Horrigan) and Union Carbide (Mr. R. Tripolet)

to evaluate use of acoustic emission techniques for use in the

periodic inspection of large steel pressure vessels. NBS is in

98
the process of developing specific procedures and test criteria to

permit the use of acoustic emission techniques for this application.

16. Howmedica, Inc.

Mr. Larry Gustavison of Howmedica has cooperated with A. C. Fraker

of NBS and provided sintered porous coated Co-Cr-Mo research materials

amd devices for use in metallurgical studies. He also provided the

Co-Cr-Mo material used for the Standard Reference Materials 1891.

17. Leco Corp.; Leitz Corp.; Reichart Corp. ; Wilson Corp.

A number of industries have been interacting with the Electrodeposition Group in the area of microhardness measurements. These

include Leco (F. Toye), Wilson (A. Fee), Reichart (C. Spinella)

,

and Leitz (A. Graf). Each of these companies has been provided

with the load-time curve for one or more of their hardness testing

instruments. Discussions of hardness testing techniques and problems

have been held at NBS with engineers of each of these companies. As

a result of these interactions, several of the commercial instruments

have been modified.

18. Luxfer USA, Inc. and Detek, Inc.

A collaborative effort between J. H. Smith of NBS and G. Waite

of Luxfer and A. Julier of Detek, Inc. has been aimed at developing

a reliable method of using eddy current techniques to inspect com- posite pressure vessels for cracks.

19. National Association of Corrosion Engineers (NACE)

The Corrosion Data Program, a cooperative effort of the National

Association of Corrosion Engineers and the National Bureau of

Standards will provide materials scientists and engineers with

computerized evaluated corrosion data. The pilot project phase

has been successfully completed and work has begun on a prototype

of the accessible database. The Corrosion Data Workshop, held

this past June, brought together over 50 corrosion specialists

from industry, government, and universities for an intensive

discussion on the present state of and future needs for evaluated

corrosion data. The findings of the workshop, which will be published

in book form, will be used to help direct the corrosion data program. NACE is seeking funding support from industry to provide

start-up and implementation costs for the full scale corrosion

data program.

20. Parker Hannifin Corporation

Research on characterizing the weldability of a leaded, resul fur 1 /.<•<!

rephosphorized carbon steel is being carried out in a cooperatlvr

program between Parker Hannifin (W. Hertel), the U.S. Coast Guard

99
(H. Hime) , and J. G. Early (Metallurgy Division) of NBS. This

research is aimed at establishing welding limits for this steel

which is not currently allowed in ship components. Welded samples

prepared with several joint geometries were provided by Parker

Hannifin for characterization at NBS.

21. Shell Oil Company

Members of the Corrosion Group took part in several meetings and

discussions with representatives of the Shell Oil Company. These

interactions, which also involved staff of the Consumer Product

Safety Commission and the Department of Transportation, were concerned with the effects of possible ammonia contamination of

liquid-propane gas on brass components in the system. Our experience

of the electrochemistry and stress corrosion cracking in the brassammonia system proved valuable in attempts to predict possible

embrittlement effects and in outlining procedures to combat potential

problems.

22. Union Carbide Corp. and Taylor-Warton, Inc.

A collaborative effort is underway between the Wear and Mechanical

Properties Group (J. H. Smith) and the Linde Division of Union

Carbide (Mr. M. Rana) and Taylor Wharton, Inc. (Mr. K. Miller)

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 /UNIVERS ITY

1. Metals Processing Laboratory Interactions

The NBS Metals Processing Laboratory is one of the special facilities

available at the National Bureau of Standards to aid researchers from

outside NBS 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 Martin Marietta, General

Electric, Carpenter Technology, Richards Medical, Naval Research

Laboratory, Naval Air Development Center, Los Alamos National

Laboratory, Massachusetts Institute of Technology, Drexel University,

University of Washington, and University of Connecticut 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.

100
UNIVERSITIES

1. Carnegie- Mellon University

Professor 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 Professor Johnson and

his students on elastic interactions in alloys is combined with the

expertise of Dr. Voorhees and co-workers at NBS on kinetic effects

has resulted in significant progress toward evaluating the effect

of stress on coarsening processes.

2. 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 four 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.

3. Johns Hopkins University

Interface characterization of composite materials using ultrasonic

techniques has also begun. The fruitful collaboration with The

Johns Hopkins University has continued with Professor Moshe Rosen

and his graduate students (T. Hsieh, J. Smith, B. Elkind and

K. Hershman) interacting strongly with group scientists to make

valuable contributions to the task.

4. Johns Hopkins University

A cooperative program has been initiated between Dr. L. H. Bennett

(Metallurgy Division), the Johns Hopkins University Applied Physics

Laboratory (Dr. K. Moorjani) and the Naval Research Laboratory

(Dr. M. Rubinstein) to measure local site symmetry and possible

magnetic interactions in the Al-Mn icosahedral phase by nuclear

magnetic resonance and with a SQUID magnetometer.

101
5. North Carolina State University

This research is a collaborative effort between Dr. H. H. Stadelmaier

and Ms. Inge K. Simonsen of N.C. State University and A. C. Fraker

(NBS) 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.

6. University of Wisconsin-Madison

Professor J. H. Perepezko (University of Wisconsin) and W. J. Boettinger

(NBS 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 rapidly

solidified powders and ribbons. This knowledge can be used to tailor

microstructures to meet specific alloy property requirements.

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 Society of Mechanical Engineers

NDE for Process Control Committee

H. N. G. Wadley, Chairman

Tribology Division, Executive Committee

A. W. Ruff

American Society for Metals

Bulletin of Alloy Phase Diagrams

J. L. Murray, Editor

Washington, DC Chapter

P. J. Blau, Vice Chairman

J. G. Early, Chairman, Yearbook 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

102
WG.05 : D. S, Lashroore, 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

E7: Nondestructive Testing

Joint Task Group on Acoustic Emission; System Calibration

J, A. Simmons, Chairman

E24

Fracture Testing

C. G. Interrante, Member of Executive Committee

E24.05: Terminology for Fracture Testing

C» G. Interrante, Chairman

E38: Resource Recovery

J. G, Early, Member- at~Large, and Member of Executive

Committee

E38.02

Ferrous Metals Resource Recovery

J, G. Early, Chairman

F4:

F4/G1:

Medical and Surgical Materials and Devices

Joint Section on Corrosion of Implants

A. C. Fraker, Co-Chairperson

F7.04: Hydrogen Embrittlement Testing

C. G. Interrante, Chairman, Task Group on Terminology

G18.99: Corrosion of Metals

Standing Committee on Liaison

E. N. Pugh, Chairman

G2:

G2.2:

Erosion and Wear

Solid Particle Erosion

A. W. Ruff, Task Group Leader

G2.9: Executive Subcommittee Task Group on Operations

L. K. Ives, Chairman

G2.91: Terminology and Definitions

P.J. Blau, Chairman

ASTM Standing Committee on Terminology

C. G. Interrante, Technical Committee Representative

P. J. Blau, Chairman, Terminology Coordinating Task Group on Tribology

ASTM Coordinating Group on Terminology for Environmental Efforts

C. G. Interrante, Convener

103
Applied Mechanics Review

R. R. Clough, Review Staff

Case Western Reserve University, Materials Research Laboratory,

NSF Visiting Committee

E. N. Pugh, Member

Electrochemical Society

Editorial Committee

U. Bertocci, Division Editor

Electrodeposition Division

D. S. Lashmore, Secretary-Treasurer

Federation of Materials Societies

U. Bertocci, S. R. Coriell and G. M. Ugiansky, Trustees

Awards Committee

G. M. Ugiansky, Chairman

Interagency Strategic Materials Stockpile Advisory Group

J. G. Early, NBS Representative

International Institute for the Science of Sintering

P. W. Voorhees, Corresponding Member

International Journal of Crystal Growth

R. L. Parker, Associate Editor

International Society of Electrochemistry

Corrosion Division

U. Bertocci, Co-Chairman

International Standards Organization

TC107 : Metallic and Other Non-organic Coatings

D. S. Lashmore, Delegate

1: Terminology

D. S. Lashmore, Delegate

2: Methods of Inspection and Coordination

of Test Methods

D. S. Lashmore, Delegate

3: Electrodeposited Coatings and Related Finishes

D. S. Lashmore, Delegate

7: Corrosion Tests

D. S. Lashmore, Delegate

TC156: Corrosion of Metals

104
G. M. Ugiansky, Delegate

2: Stress Corrosion

G. M. Ugiansky, Delegate

TC164: Medical Testing

1. Terminology

C. G. Interrante, Delegate

Maryland Institute of Metals

W. J. Boettinger, Executive Board Member

Materials Science and Engineering

L. H. Bennett, Associate Editor

Mechanical Failures Prevention Group

Committee on Mechanisms of Failure

J. G. Early, Chairman

Committee on Fuel Cell Materials Technology in Vehicular

Propulsion

U. Bertocci, Liaison Representative

National Association of Corrosion Engineers

G. M. Ugiansky, Director, ex officio, Board of Directors

Government Affairs Committee

G. M. Ugiansky, Chairman

Office of Energy-Related Inventions, National Bureau of Standards

J. G. Early, Reviewer of Invention Disclosures

Read Research Conferences

Organizing Committee

D. S. Lashmore, Member

Society of Automotive Engineers

Committee on Automotive Trim

D. S. Lashmore, Invited Member

Society of Automotive Engineers/American Society of Testing

and Materials Unified Numbering System for Metals and Alloys

L. H. Bennett, NBS Representative

Society for Biomaterials Standards

A. C. Fraker, Chairperson, Representative

U.S. Civil Service Examiners for Metallurgist

Interagency Board

J. G. Early, Chairman

105
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

ASSOCIATED ACTIVITIES

Members of the Metallurgy Division have been very active during the year

in transferring the results of their scientific research to the technical

community through a variety of means. Over 60 invited talks were presented

at industrial laboratories, technical society symposia, and international

conferences. A major corrosion workshop was organized to focus on how

the needs of the material industry for corrosion data could be satisfied

through the National Association of Corrosion Engineers-National Bureau of

Standards Corrosion Data Center. Division scientists wrote or edited

five books on topics related to alloy phase diagrams, wear and tribology,

and electrodeposition. In the area of providing certified or standard

materials for the calebration and standardization needs of U.S. industry,

five new Standard Reference Materials for implant materials, coating

thickness gages, and corrosion studies were developed by Division researchers and placed on sale by NBS. In the area of electrodeposition technology,

microhardness testing, and amorphous alloys patents have been granted or are in preparation.

106
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BIBLIOGRAPHIC DATA

SHEET (Scr inuructlon 1)

1 PUBLICATION OR

’ REPORT NO.

NBSIR-85/3191

"porfoowloi On*".

Publication Data

NOVEMBER 1985

4. TITLE AND SUBTITLE

Metallurgy Technical Activities 1985

NBSIR 85-3191

5. AUTHOR(S) _ . E. N. Pugh and J.6. Early

PERFORMING ORGANIZATION flf |o.«*. oi .|tow NPS. ...

national bureau or standards

DEPARTMENT OF COMMERCE

WASHINGTON. O.C.

7. Contract/Cr*n‘ No.

». Typo of Raport A Parlod Covarad

$. SPONSORING ORGANIZATION NAME AND

10. SUPPLEMENTARY NOTES

rc iar p,pc Software Summary. Is attactvad. T~| Document daacribaa a computer pcoyam.^

* f

1(l formo«lo«. If ***'""' Inclutfaa a •'»"» f'c-t T ABSTRa/:t (A XV>-word or lt» /actual Sum^.o( "*“11 ' l

* £“I£phy or future .„rvay. m.ntion ^ABSTRACT

. * Metallurgy Division of the

Thi. report the FY 1983 upon the .tructure-proee.^-

National Bureau of Standard®. The ^

on the methods of their

characterization, metallurgical proceaa electrodeposition. and nondestructive

S Corroeion 5L£3=.«S «-*• -""jETSTS'

Sensor Prograa. The sciencii f

91 full_t lae and part-time me*

and other professional ntera

re8earchera are identified.

Metallurgy Division and its
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