nano and microstructural design of advanced materials, 2003, p.317

NAN0 AND MICROSTRUCTURAL DESIGN
OF
ADVANCED MATERIALS
A Commemorative Volume on Professor G. Thomas’
Seventieth Birthday
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NAN0 AND MICROSTRUCTURAL DESIGN
OF
ADVANCED MATERIALS
A Commemorative Volume on Professor G. Thomas’
Seventieth Birthday
Edited by
M.A. MEYERS
University
of
California, San Diego,
USA
R.O. RITCHIE
University
of
California, Berkeley,
USA
and
M. SARIKAYA
University
of
Washington,
USA
2003
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Preface
The importance of the nanoscale effects has been recognized in materials research for over fifty
years. The understanding and control of the nanostructure has been, to a large extent, made
possible by new atomistic analysis and characterization methods. Transmission electron
microscopy revolutionized the investigation of materials. This volume focuses on the effective
use of advanced analysis and characterization methods for the design of materials. The nano-
structural and microstructural design for a set of targeted mechanicaVfunctiona1 properties has
become a recognized field in Materials Science and Engineering. This book contains a series
of authoritative and up-to-date articles by a group of experts and leaders in this field. It is based
on a three-day symposium held at the joint TMS-ASM meeting in Columbus, Ohio. The book
is comprised of three parts: Characterization, Functional Materials, and Structural Materials. The
book is dedicated to Gareth Thomas who has pioneered this approach to materials science and
engineering area over a wide range of materials problems and applications.
Professor Thomas’ lifetime in research has been devoted to understanding the fundamentals
of structure-property relations in materials for which he has also pioneered the development

and applications of electron microscopy and microanalysis. He established the first laboratory for
high voltage electron microscopy, at the Lawrence Berkeley National Laboratory. His research
has contributed to the development and nano/microstructural tailoring of materials from steels
and aluminum alloys, to high temperature and functional ceramics and magnetic materials, for
specific property performances, and has resulted in a dozen patents.
Professor Thomas is a pioneer and world leader in the applications of electron microscopy
to materials in general. Following his Ph.D. at Cambridge in 1955, as an ICI Fellow, he
resolved the problem of intergranular embrittlement in the AVZn/Mg high strength alloys
which failed in the three Comet aircraft crashes and became identified with Prof. Jack Nutting
as the “PFZ’ -precipitate-free-zones, condition, now in wide general use to describe grain-
boundary morphologies leading to intergranular corrosion and mechanical failure. This work
prompted Dr. Kent van Horne of Alcoa to invite him to spend the summer of 1959 in their
research labs at New Kensington, Pa. From there and after a trans-USA lecture tour he was
invited in 1960 to join the Berkeley faculty, (becoming a full professor in 1966), where he
started a major research program within the newly formed “Inorganic Materials Research
Division” of the (now) Lawrence Berkeley National Laboratory. It was there, after nine years’
effort, that he founded the National Center for Electron Microscopy, which opened in 1982 and
which he directed until he resigned in 1993, to spend 1.5 years helping establish the University
of Science
&
Technology in Hong Kong. There he also set up and directed the Technology
Transfer Centre. He returned to Berkeley in 1994 to continue teaching and research, and in his
career has over 100 graduates. With his students and colleagues he has over
500
publications,
several books, including the first text on
Electron Microscopy ofMetals
(1962), and in 1979 -with
M.J. Goringe, a widely used referenced text- Transmission Electron Microscopy of Materials
which was also translated into Russian and Chinese.

His academic career in Berkeley has included administrative services as Associate Dean,
Graduate Division, Assistant and Acting Vice-Chancellor-Academic Affairs, in the turbulent
years of student unrest (1966-72). He was the Chair faculty of the College of Engineering
(1972/73), and Senior Faculty Scientist, LBNL-DOE, which sponsored most of his research
V
Vi
Preface
funding. In 1995 he received the Berkeley Citation for “Distinguished Achievement” at UC
Berkeley. Professor Thomas was Associate Director, Institute for Mechanics and Materials,
UC San Diego, from 1993 to 1996. In this capacity, he formulated new research directions and
stimulated research at the interface of Mechanics and Materials. He is currently Professor in the
Graduate School, UC Berkeley, Professor-on-Recall, UC San Diego, and VP R&D of a new
company, MMFX Technologies, founded in 1999, to utilize steels for improved corrosion
resistant concrete reinforcement. In the USA the infrastructure repair costs are in the trillion
dollar range. In 2002 the company received the Pankow award (American Inst. of Civil Engineers)
for innovation in Engineering, based on Prof. Thomas’ patents on nano microcomposite steels.
Professor Thomas has also played an important role in promoting the profession. He was
president of the Electron Microscopy Society of the US in 1974, and in 1974 he became
Secretary General of the International Societies for Electron Microscopy for an unprecedented
12 years, and was president in 1986-90. He lectured extensively in foreign countries and
helped promote microscopy and materials in developing countries, also serving as advisor in
China, Taiwan, Korea, Singapore, Poland, Mexico, et al. He also served on many committees
of the ASM and TMS, and the National Research Council. After reorganizing the editorial
structure of Acta and Scripta Metallurgica (now Materialia), when in 1995 he took over as
Editor-in-chief, he became Technical Director, Acta Mat. Inc. 1998 until April 2002. He was
Chairman of the Board in 1982/84.
In recognition of his many achievements, Professor Thomas has received numerous honors
and awards, including, besides his Sc.D Cambridge University in 1969: Honorary Doctorates
from Lehigh (1996) and Krakow (1999); The Acta Materialia Gold Medal (2003), The ASM
Gold Medal (200 l), Sauveur Achievement Award (ASM- 199 l), Honorary Professor, Beijing

University of Sci.
&
Technology (1958), Honorary Memberships in Foreign Materials societies
(Japan, Korea, India, etc.), E.O. Lawrence Award (US Dept. of Energy-l978), Rosenhain
Medal (The Metals Soc-UK-1977), Guggenheim Fellow (1972), von Humboldt Senior Scientist
awards (1996
&
1981), the I-R Award (R&D Magazine-1987), Sorby Award,
(IMS-
1987) and
the Distinguished Scientist Award (EMSA-1980). He received the Bradley Stoughton Teaching
Award (ASM) in 1956, and the Grossman (ASM), and Curtis-Mcgraw (ASEE) research awards
in 1966. He is a Fellow of numerous scientific societies. In recognition of these achievements,
Professor Thomas was elected to both the National Academy of Sciences (1983) and the
National Academy of Engineering (1982). Professor Thomas, born in South Wales, UK, is also
a former rugby and cricket player (member, MCC), enjoys skiing and grand opera.
The editors thank the speakers at the symposium and the authors of the scholarly contributions
presented in this volume. A special gratitude is expressed to Prof.
S.
Suresh for having enabled
the publication of this volume by Elsevier. All royalties from the sale of this book are being
donated to the TMS/AIME and ASM societies for the establishment of an award recognizing
excellence in Mechanical Behavior of Materials.
November, 2003
Curriculum Vitae of Professor Thomas
Date and Place of Birth: 9 August 1932, Maesteg, Glamorgan, U.K.
Academic Qualifications
B.Sc. with First Class Honors in Metallurgy, University of Wales (Cardiff), 1952.
Ph.D. University of Cambridge, 1955; Sc.D. University of Cambridge, 1969.
Career Details

1956-59 ICI and St. Catharine’s College Fellow, University of Cambridge
1960 Visiting Assistant Professor, University of California, Berkeley
1961-Present
University of California, Berkeley: Full Professor (1966); Associate Dean,
Graduate Division (1968-69); Assistant to the Chancellor (1969-72); Acting
Vice Chancellor, Academic Affairs (1971-72); Chairman, Faculty of the College
of Engineering (1972-73); Senior Faculty Scientist, Materials Sciences Division,
Lawrence Berkeley Laboratory; Founder and Scientific Director, National Center
for Electron Microscopy, Lawrence Berkeley Laboratory (198 1-93); on special
leave as Director, Technology Transfer Centre, Hong Kong University of Science
and Technology, Kowloon, Hong Kong (1993-94); Professor in the Graduate
School, University
of
California, Berkeley (1995-present).
Awards and Honors
2003
2003 Acta Materialia Gold Medal
200
1
Silver Medal in honor of Prof. C.
S.
Barrett, ASM Intl. Rocky Mountain Chapter
First Albany Int. Distinguished Lecture in Mat. Sci.
&
Eng.
(RPI).
Vii
Viii
200 1
1999

1998
1996
1996
1996
1996
1995
1994
1994
1991
1987
1987
1987
1985
1983
1983
1982
1981
1980
1979
1978
1977
1976
1976
1973
1971-72
1966
1966
1965
1964
1953

Curriculum vitae
of
Professor
Thomas
American Society for Materials International, Gold Medallist
Doctorate
honoris causa,
University of Krakbw, Poland
Honorary Member, Japan Institute of Materials
Honorary D.Sc., Lehigh University, Bethlehem, PA, USA,
1996
Honorary Member, Indian Institute of Metals
Honorary Member, Korean Institute of Metals and Materials
Alexander von Humboldt Senior Scientist Award, IFW, Dresden, Germany
The Berkeley Citation for Distinguished Achievement, U. C. Berkeley
Honorary Member, Mat. Res. SOC. of India
Medal of Academy of Mining and Metallurgy, Polish Acad. of Sciences, Krakow
Albert Sauveur Achievement Award (ASM International)
I-R
100
Award, Research and Development Magazine
Elected, Fellow, Univ. Wales, Cardiff, UK
Henry Clifton Sorby Award, International Metallographic Society
Honorary Professorship-Beijing University of Science
&
Technology
Confucius Memorial Teaching Award, Republic of China (Taiwan)
Elected to the National Academy of Sciences, U.S.A.
Elected to the National Academy of Engineering, U.S.A.
Alexander von Humboldt Senior Scientist Award, Max Planck Institute, Stuttgart

EMSA Distinguished Scientist Award for Physical Sciences
Fellow, Metallurgical Society of AIME
Ernest
0.
Lawrence Award (US. Department of Energy)
The Rosenhain Medal (The Metals Society, U.K.)
Fellow, Royal Microscopical Society, U.K.
Fellow, American Society for Metals
Visiting Professor at Nagoya University, Japan Society for Promotion of Science
Guggenheim Fellow; Visiting Fellow, Clare Hall, Cambridge University
Curtis-McGraw Research Award (American Society for Engineering Education)
Grossman Publication Award (American Society for Metals) for paper “Structure
and Strength of Ausformed Steels”, Trans. ASM,
58,563 (1965)
Bradley Stoughton Teaching Award, American Society for Metals
Miller Research Professor, UC Berkeley
National Undergraduate Student Prize, Institute of Metals (London)
Professional Activities
1998-
1995-98
1992
1991-95
1986-90
1974-86
1991-94
1987-88
1982-85
1985-90
Managing Director, Acta Metallurgica, Inc. Board of Governors
Editor in Chief,

Acta Materialia
and
Scripta Materialia
Founder Member, Editorial Board,
NanoStructured Materials
(Elsevier)
Vice President, International Federation of Societies for Electron Microscopy
President, International Federation of Societies for Electron Microscopy
Secretary General, International Federation of Societies for Electron Microscopy
Reappointed, Member, Board of Governors Acta Metallurgica, Inc.
Member, US Department of Energy E.
0.
Lawrence Award Selection Committee
Chairman, Acta Metallurgica, Inc. Board of Governors
Member, Acta Metallnrgica, Inc. Board
of
Governors
Curriculum vitae
of
Professor
Thomas
ix
1978-8 1 TMS-AIME Board of Directors
1975 President, Electron Microscopy Society of America
1972-73 UC Convenio Program Visiting Professor, University of Chile, Santiago, Chile
1961-present Served on many national and international committees including National
Research Council (USA), International Federation of Electron Microscopy
Societies, EMSA, ASM, TMS, University of California, editorial boards, etc.
Served on science and technology boards (Taiwan, Singapore, Korea, South
Africa and Mexico) as materials advisor.

Publications
Over 550 papers, 2 books, numerous book chapters.
Selected Publications
1. “Structure-Property Relations: Impact on Electron Microscopy,” in
Mechanics and Materials:
Fundamentals and Linkages,
Marc A. Meyers, Ronald W. Armstrong and Helmut
Kirchner, eds. New York:
J.
Wiley
&
Sons, 1999, pp. 99-121; LBNL 40317.
“Nd Rich Nd-Fe-B Tailored for Maximum Coercivity,” Er. Girt, Kannan M. Krishnan,
G. Thomas, C.
J.
Echer and Z. Altounian,
Mat. Res. SOC. Symp. Proc.
577,
Michael Coey
etal.,
eds. Warrendale, PA: The Materials Research Society, 1999, pp. 247-252.
3. “Some Relaxation Processes in Nanostructures and Diffusion Gradients in Functional
Materials,” G. Thomas, in
Deformation-Induced Microstructures: Analysis and Relation to
Properties
(Proc. 20th Ris# International Symposium on Mat. Sci.,),
J.
B. Bilde-S#rensen,
J.
V. Carstensen, N. Hansen, D. Juul Jensen, T. Leffers, W. Pantleon,

0.
B. Pedersen and
G. Winther, eds., Ris# National Laboratory, Roskilde, Denmark, 1999, pp. 505-521.
“Origin of Giant Magnetoresistance in Conventional AlNiCo, Magnets,” A. Hiitten,
G.
Reiss, W. Saikaly and
G.
Thomas,Actu Muteriuliu
49,
827-835 (2001).
“Novel Joining of Dissimilar Ceramics in the Si3N4-Al2O3 System Using Polytypoid
Functional Gradients,” Caroline
S.
Lee, Xiao Feng Zhang and Gareth Thomas,
Acta Materialia
vo1.49,3767-3773,
&
3775-3780 (2001).
2.
4.
5.
See web-site (below) for more details:
Internet:

Patents
Process for Improving Stress-Corrosion Resistance of Age-Hardenable Alloys, U.S. Patent
3,133,839 (1964).
High Strength, High Ductility Low Carbon Steel
(J.
Koo and G. Thomas), U.S. Patent

4,067,756 (1978).
High Strength, Tough Alloy Steels (G. Thomas andB. V. N. Rao), U.S. Patent4,170,497 (1979).
Method of Making High Strength, Tough Alloy Steels (G. Thomas and B. V. N. Rao), U.S.
Patent 4,170,499 (1979).
High Strength, Low Carbon, Dual Phase Steel Rods and Wires and Process for Making Same
(G. Thomas and A. Nakagawa). U.S. Patent 4,613,385 (1986).
X
Curriculum vitae
of
Professor
Thomas
Controlled Rolling Process for Dual Phase Steels and Applications to Rod, Wire, Sheet and
Other Shapes (G. Thomas,
J.
H. Ahn, and N.
J.
Kim),
U.S.
Patent 4,619,714 (1986).
Method of Forming High-Strength, Corrosion-Resistant Steel (G. Thomas, N.
J.
Kim, and
R. Ramesh),
U.S.
Patent 4,671,827 (1987).
Method of Producing a Dense Refractory Silicon Nitride (Si3N4) Compact with One or More
Crystalline Intergranular Phases (G. Thomas,
S.
M. Johnson, and T. R. Dinger),
U.S.

Patent
4,830,800 (1989).
High Energy Product Permanent Magnet Having Improved Intrinsic Coercivity and Method of
Making Same (R. Ramesh and G. Thomas),
U.S.
Patent 4,968,347 (1990).
Giant Magnetoresistive Heterogeneous Alloys and Method of Making Same
(J. J.
Bernardi,
G. Thomas, and A. R. Huetten),
US.
Patents 5,824,165 (1998) and 5,882,436 (1999).
Table
of
Contents
Preface
Curriculum Vitae of Professor Thomas
Part 1: Characterization
Characterization: The Key to Materials
R.
Gronsky
Nanochemical and Nanostructural Studies of the Brittle Failure of Alloys
D.
B.
Williams, M. Watanabe, C. Li and V. J. Keast
Transmission Electron Microscopy Study of the Early-Stage
Precipitates in Al-Mg-Si Alloys
H.
W. Zandbergen, J.H. Chen, C.D. Marioara and E. Olariu
Laser Surface Alloying of Carbon Steels with Tantalum,

Silicon and Chromium
J. Kusinski and A. Woldan
In-Situ TEM Observation of Alloying Process in Isolated
Nanometer-Sized Particles
H.
Mori, J G. Lee and H. Yasuda
Characterization of MetaVGlass Interfaces in Bioactive Glass
Coatings on Ti-6A1-4V and Co-Cr Alloys
E.
Saiz,
S.
Lopez-Esteban,
S.
Fujino, T. Oku, K. Suganuma and A.P. Tomsia
Development of Advanced Materials by Aqueous Metal Injection Molding
S.K. Das, J.C. LaSulle, J.M. Goldenberg and J. Lu
Part
2:
Functional Materials
Microstructural Design of Nanomultilayers (From Steel to Magnetics)
G.J. Kusinski and G. Thomas
Effects of Topography on the Magnetic Properties
of
Nano-Structured
Films Investigated with Lorentz Transmission Electron Microscopy
J.Th.M. De Hosson and N.G. Chechenin
Slip Induced Stress Amplification in Thin Ligaments
X.
Markenscogand V.A. Lubarda
Materials, Structures and Applications of Some Advanced MEMS Devices

Sungho Jin
V
vii
3
11
23
35
49
61
69
81
93
109
117
xi
xii
Table
of
contents
Microstructure-Property Evolution in Cold-Worked Equiatomic Fe-Pd
During Isothermal Annealing at 500
O
A. Deshpande, A. Al-Ghaferi, H. Xu, H. Heinrich and J.M.K. Wiezorek
Part
3:
Structural Materials
Microstructure and Properties of
In
Situ
Toughened Silicon Carbide

L.C. De Jonghe, R.O. Ritchie and X.F. Zhang
Microstructure Design of Advanced Materials Through Microelement Models:
WC-Co Cermets and Their Novel Architectures
K.S. Ravi Chandran and Z. Zak Fang
The Ideal Strength of Iron
D.M. Clatterbuck, D.C. Chrzan and J. W. Morris Jr.
Microstructure-Property Relationships of Nanostructured Al-Fe-Cr-Ti Alloys
L. Shaw, H. Luo, J. Villegas and D. Miracle
Microstructural Dependence of Mechanical Properties in Bulk
Metallic Glasses and Their Composites
U.
Ramamurty, R. Raghavan, J.
Basu
and
S.
Ranganathan
The Bottom-Up Approach to Materials by Design
W. W. Gerberich, J.M. Jungk and W.M. Mook
The Onset of Twinning in Plastic Deformation and Martensitic Transformations
M.A. Meyers, M.S. Schneider and
0.
Voehringer
Crystal Imperfections Seen by X-Ray Diffraction Topography
R. W. Armstrong
Synthetic Multi-Functional Materials by Design Using Metallic-Intermetallic
Laminate (MIL) Composites
K.S. Vecchio
Taylor Hardening in Five Power Law Creep of Metals and Class M Alloys
M.E. Kassner and K. Kyle
Microstructural Design of 7x50 Aluminum Alloys for Fracture and Fatigue

F.D.S. Marquis
Elastic Constants of Disordered Ternary Cubic Alloys
C.S. Hartley
145
157
173
191
199
21 1
221
233
243
255
273
287
Index 299
PART
1:
CHARACTERIZATION
This Page Intentionally Left Blank
Nan0 and Microstructural Design
of
Advanced Materials
M.A. Meyers,
R.O.
Ritchie and M. Sarikaya (Editors)
0
2003
Elsevier Ltd. All rights reserved.
CHARACTERIZATION: THE

KEY
TO MATERIALS
R.
Gronsky
Department of Materials Science
&
Engineering, University of California
Berkeley, California
94720-1760
USA
ABSTRACT
His seventieth birthday offers this special occasion to recall the many seminal contributions made by Professor
Gareth Thomas to the field of materials science and engineering. A brief reckoning
of
his career, his
dedication to the development of electron microscopy techniques, his applications of high precision
characterization methods to numerous engineering materials systems, and his successes as both researcher and
educator are recounted here.
INTRODUCTION
The development
of
advanced materials is guided by
assessment
at appropriate levels of resolution. This has
always been the preferred protocol, and hallmark, of materials science and engineering.
Our
discipline seeks to
understand all of the links connecting the synthesis and processing of materials with the evaluation of their
properties, with their performance in engineering applications, and with their internal structure and
composition. However, as modem engineering progresses towards increased complexity and reduced

dimensionality,
our
discipline places ever higher demands on the diffraction, spectroscopy, and microscopy
techniques used for microstructural analysis.
There was a time when “pearlite” was an acceptable designation
for
a microstructural constituent associated
with certain mechanical properties
of
steels. Thirty years ago, it became essential
to
know the composition of
both
the ferrite
and
the cementite in “pearlite,” including whether
or
not there were any gradients in carbon
concentration at their contiguous interfaces. And as this manuscript is being written, hundreds of scientists
around the world are struggling to sort out carbon nanotubes as single-walled or multi-walled, spiral
or
concentric, vacant or filled, with what species, at which specific locations. Consequently, the levels of
resolution appropriate for contemporary materials science and engineering are those that reveal
individual
atomicpositions
in the spatial domain, and
individual atomic identities
in the temporal
or
energy domain. It is

now generally accepted that atomic level characterization is the essential key to materials, old and new.
Today’s symposium highlights many of the triumphs of advanced materials development based upon this
singular tenet of microstructural design, which has been championed by Professor Gareth Thomas throughout
his long and illustrious career. It was just over thirty
(30)
years ago that
I
came to Berkeley to begin my
graduate studies in Professor Thomas’s group, and I’m honored to offer this contribution in celebration of his
seventieth
(70th)
birthday.
3
4
R.
Gronslcy
BACKGROUND
Gareth Thomas was born on August 9, 1932. He completed his Bachelor of Science degree with First Class
Honors in Metallurgy from the University of Wales, Cardiff, in 1952.
Three
years later, in 1955, he obtained
his Ph.D. from the University
of
Cambridge, where he stayed through 1959 as an ICUSt. Catherine’s College
Fellow. In 1960 he arrived in Berkeley as a Visiting Assistant Professor and joined the ladder rank faculty as
an Assistant Professor in 1961.
During his first year on the faculty, when other assistant professors seeking tenure were buried in labs
or
libraries struggling to solidify their academic careers, Professor Thomas chose instead to organize an
international conference. Securing a prime location

on
the Berkeley campus, he hosted “The Impact of
Transmission Electron Microscopy on Theories of the Strength of Metals” in 1961, providing an aggressive
examination of the Orowan and Petch equations as well as new insights into the mechanisms of strengthening
by finely dispersed (TEM-sized) obstacles. Many of the luminaries in the fledgling field of transmission
electron microscopy were there (Figure l), taking note of both the ambition and the dedication their colleague
Gareth Thomas, who would continue this tradition of global congresses to advance the practice of electron
microscopy in applications to engineering materials throughout his career.
Figure
1:
A
few of the attendees
at
the
1961
Berkeley conference
on
the
“Impact of TEM on Theories of the Strength of Metals.”
L
to
R
first
row, R.B.
Nicholson,
M.J.
Whelan,
G.
Thomas,
J.

Washbum;
L
to
R
second row,
K.
Melton,
A.
Kelly,
G.
Rothman, P.R. Swann.
Also during his first year on the faculty, Professor Thomas found time to draft and edit a complete textbook,
Transmission Electron
Microscopy
of
Metals,
published by Wiley only one year later, in 1962. This treatise
was the first of its kind, a practical, pedagogical, “hands-on” treatment of the transmission electron microscopy
technique, annotated with instructions on how to prepare representative samples worthy of scientific
investigation. It served generations of students for the next 17 years, until his second edition, co-authored with
M.J. Goringe, was released in 1979.
Thomas’s early emphasis on high-resolution microstructural characterization of metals was born of his notable
successes during his time at Cambridge. One of the most perplexing problems of the day was the catastrophic
failure of the Comet aircraft, prompting many investigations into the relationship between the microstructure
and deformation behavior of aluminum-based alloys. Thomas’s work
[
1,2] showed quite clearly (Figure
2)
the
occurrence of a precipitate-free zone (PFZ) adjacent to grain boundaries, and a coarser precipitate distribution

adjacent to the PFZ, when compared to the surrounding matrix.
Implicating such inhomogeneities in microstructure as the likely cause for inhomogeneities in mechanical
response, the path forward was revealed through microstructural design. Subsequent development of thermo-
mechanical processing cycles to eliminate the formation of PFZs and their attendant problems was facilitated
by electron microscopy, the only technique with sufficient spatial resolution to verify success.
Professor Thomas developed similar processing methodologies to protect age-hardening alloys against stress-
corrosion cracking (Figure 3), resulting in his first patent
[3],
also issued within a few short years of his debut
on the faculty.
Characterization: The key to materials
5
Figure
2:
Heterogeneous precipitation and precipitate-free zones
(PFZs)
in AI-6Zn-3Mg, after reference [2].
BI
n
3%
I
.s
*li
r;-
Figure
3:
Plot
of average
stress
corrosion life (days)

vs
aging time
(hours)
for
aluminum alloys subjected to step agmg process, after
reference [3].
EARLY
DEVELOPMENTS
In his quest for precision during diffraction analysis, Professor Thomas became an early advocate for the
technique of Kikuchi electron diffraction
[4],
which results from an inelastic scattering event that is
subsequently elastically scattered. Thomas and co-workers released a series of publications in the
1960s
explaining the method and demonstrating its superior advantages over conventional (spot) electron diffraction
for precise determination of crystalline orientations. By painstakingly assembling photo collages combining
hundreds of Kikuchi electron diffraction patterns, they also generated “Kikuchi maps” to assist investigators in
navigating reciprocal space. Figure
4
shows one such map for the diamond cubic structure
[5],
but others were
published for both body-centered cubic
[6]
and hexagonal close-packed
[7]
structures.
Diffraction also figured prominently in the analysis of spinodal decomposition, but there was no more
convincing evidence of structural modulation that the images published by Thomas and co-workers
[S],

Figure
5(a). Coarsening of the spinodally-decomposed product resulted in a square wave compositional profile seen
in Figure 5(b), which was much
less
obvious, and sometimes completely obscured, in diffraction results.
Thomas was also first to point out that microstructures generated by spinodal decomposition were not
6
R.
Gronslcy
susceptible
to
the formation of detrimental PFZs, and he proposed employing spinodal decomposition where
possible in alloy systems with known miscibility gaps
as
another method of intelligent microstructural design.
Figure
4.
Kikuchi map of the diamond-cubic structure (silicon) after
reference
[5]
The top pole
is
readily identified by its four-fold
symmetry as
001,
the bottom center pole
is
113,
representing an angular
range of

25
2”
East-west extremes are
102
and 012 poles, at
36
9”
apart
Figure
5:
Spinodally decomposed
Cu-Ni-Fe
alloy showing (a) early
stage and (b) later stage product resulting from aging within the temary
miscibility gap. The light phase
is
Cu
rich, the dark phase, Ni-Fe rich.
Yet another method of microstructural analysis pioneered about this time was the application of phase contrast
‘‘lattice’’ imaging to directly assess the local lattice parameter in close-packed metallic alloys. The resolution
performance of transmission electron microscopes was limited thirty years ago to approximately
0.25
nm,
consequently
a
two-beam “sideband imaging method was the only feasible option for extracting phase
contrast, generating images of
a
single spatial frequency. Figure
6

shows how the technique yielded the
modulation wavelength in
a
spinodally decomposed Au-Ni alloy, the first such demonsbation
of
its
type.
Thomas and co-workers continued to apply lattice imaging to
a
range of spinodal and ordered alloys during the
late
1970s,
coupled to the development of subsidiary analytical techniques such
as
optical microdiffraction
[9].
As
specimen preparation procedures for non-metallic materials
also
improved in Thomas’s laboratories, phase
contrast methods yielded new insights into novel polytypoid formation in the non-oxide ceramics. The
example shown in Figure
7
documents the substructure of
a
beryllium silicon nitride, BesSi3Nl0,
as
alternating
stacking sequences of three layers of BeSiN2 followed by two layers of Be3N2.
Characterization: The key to materials

I
24t
30
60
90
120
i
12
I
*
0
20
40
60
DISTANCE
(NO
OF
FRINGES)
Figure
6
Lattice image (top) and plot of d-spacing
vs
distance in
a
spinodally-decomposed Au-Ni alloy The “average” modulation
wavelength
IS
2.9
nm, after reference
[9].

INNOVATIONS
These successes with a growing number
of
applications of electron microscopy in materials engineering were
clearly noticed by the scientific community at large. Consequently Professor Thomas chose to convene another
gathering of participants in 1976 for the purpose of addressing what had become a burning question for him
and many others:
The
question
originated in the understanding that electron microscopy had taken on the earmarks of “big” science, requiring
multi-million dollar investments in order to construct, maintain, and run the high voltage electron microscopes
that exhibited superior performance at the time. Attendees included eighteen
(1
8) from Berkeley, forty-one
(41)
from elsewhere in the
US,
and seven (7)
from
abroad, and at the end of the workshop, all concurred that
the time was right to seek a national, shareable, user resource in the model of the photon beam lines and
es
that had recently been funded by the federal government. The original estimate for
this facility was a modest $5M. In rapid succession, the Energy Research and Development Administration
(later DOE) held two national Materials Sciences Overview meetings, the proceedings of which were published
as ERDA 77-76-1 and ERDA 77-76-2
.
In these reports, the Office of Basic Energy Sciences identified
a
“critical need” for state-of-the-art fa in transmission electron microscopy. Thomas and collaborators

submitted their proposal that year, and the Atomic Resolution Microscope (ARM) became a line item in the
FY
1980 Congressional Budget at
$4.3M
[Ill. The ARM was installed in 1982 and sustained the best imaging
“Should the
US
support a National Center for Electron Microscopy?’
8
R.
Gronsky
performance
of
any transmission electron microscope in the world for the next decade. With a top operating
voltage
of
1
MeV, a biaxial tilt stage
of*45’
range, and an instrumental resolution limit of
0.16
nm, it’s utility
extended
to
many new materials engineering problems requinng microstructural assessment at the atomic level.
Moreover, the technological innovations funded by the federal government dunng this project spawned a new
generation
of
“medium voltage” instruments with enhanced performarxe and smaller footpnnt,
so

they could
be placed in a “normal” laboratory setting, instead
of
the three-story silo architecture needed by the larger
megavolt units.
Figure
7:
Phase contrast image
of
Be9Si3NIo (left) and structural model
(right) showing three layers of
BeSiNl
interspersed with two layers
of
Be,N2,
after
[lo].
One
of
the most widely publicized images from the ARM is shown in Figure
8,
showing the atomic structure of
the double-layer defect in the high Tc superconductor,
YBCO.
Figure
8:
Phase contrast image of YBa2Cu3O,.* (left) and structural
model (right) showing
double
layer CuO defect running horizontally

through center
of
micrograph,
after
[
1
I].
Only cations are visible.
It
is instructive
to
compare Figures
7
and
8
for their historical significance since they represent best practice in
“contemporary” transmission electron microscopy, published in the world’s premiere scientific journals, one
decade apart. The legacy of innovation that has distinguished Professor Gareth Thomas’s career is clearly
revealed in these images.
Characterization: The key to materials
9
LEGACY
But Professor Thomas’s legacy extends well beyond his contributions to the field of electron microscopy. His
innovations in the development of novel materials and processing procedures have resulted in a dozen patents.
The first, described above, was issued for a process to enhance resistance to stress corrosion cracking in A1
alloys. Six more patents cover his development of new steels, some high-strength, some dual phase [14], and
some corrosion-resistant. Another patent was granted for a method to produce dense refractory ceramics [15].
And his four most recent patents are for magnetic materials, to enhance intrinsic coercivity and to enhance their
giant magnetoresistive (GMR) response [16].
Professor Thomas’s contributions to the scientific literature number over five hundred

(500)
and counting.
Even more impressive than this number is the range of topics on which he’s written. Metals and alloys,
ceramics, semiconductors, superconductors, magnetic materials, composite materials, polymeric materials, and
even organic materials appear in his manuscripts, along with a widely varied range of electron microscopy,
diffraction, and spectrometry methodologies used for their characterization.
One of very few individuals to have been elected to membership in
both
the National Academy of Engineering
(1982)
and
the National Academy of Sciences (1983), Professor Thomas’s recent awards include the Gold
Medal from ASM International (2001), a Doctorate
Honoris Causa
from the University of Krakow, Poland
(1999), election as an Honorary Member of the Japan Institute of Metals (1998), an Honorary D.Sc. from
Lehigh University (1996), election as an Honorary Member of the Indian Institute of Metals (1996), election as
an Honorary Member of the Korean Institute of Metals and Materials (1996), a Humboldt Senior Scientist
Award (1996), and the highest award given by his home campus, the Berkeley Citation for Distinguished
Achievement (1995).
Professor Thomas’s dossier of service is equally rich. He devoted four years as Editor in Chief of
Acta
Materialia
and
Scripta Materialia,
currently continuing as a Technical Director (1998-), another four years as
President of the International Federation of Societies of Electron Microscopy, four years as a Member of the
Board of Governors of
Acta Metallurgica,
Inc., another four years as Chairman of the Acta Metallurgical, Inc.,

Board of Governors, and four more years as a member of the TMS-AIME Board of Directors, among
other
appointments of lesser duration, such as his one year (1993) term as Director of the technology Transfer Center
at the Hong Kong University of Science and Technology, and one year (1975) reign as President of the
Electron Microscopy Society of America.
As he engages his seventy-first year, Professor Thomas is enjoying his honorable
emeritus
status on the faculty
after having supervised more than one hundred (100) students through the pursuit of their graduate degrees. He
has taught thousands more, undergraduate, graduate, and post graduate, in lectures and seminars at home and
abroad.
But, as expected, Gareth Thomas is not “retired.” He currently holds the position of Vice President of
Research and Development for MMFX Steel Corporation of America, returning to one of his favorite
metallurgical pastimes: enhancing the performance of steel. In an aggressive campaign to extend the lifetime
of rebar used in concrete construction, Thomas has claimed another success through clever microstructural
design. By replacing the ferrite/carbide microstructure common to low carbon rebar-stock steels with a “dual-
phase” microstructure (ferrite/martensite,
or
austenite/martensite) through simple adjustments in processing, an
astoundingly superior corrosion resistance has been demonstrated, with high payoff potential for applications in
marine environments. There can be little doubt that Professor Thomas’s legacy will continue to live on through
these and other advances made by materials characterization in the Thomas tradition.
10
R.
Gronsky
SUMMARY
Accomplished in science, accomplished in engineering, and accomplished in academia, Gareth Thomas has
certainly made his mark on the historical record. It is also clear that he leaves all of
us
a timeless message. It

first appeared in the preface to his textbook
Transmission Electron Microscopy
of
Metals,
dated 1961.
“Over the last twenty-five years electron microscopy has become an increasingly
popular technique for examining materials.

The tremendous advantage of the
transmission technique is, of course, that the results obtained are
visual
and therefore
convincing.”
Over the intervening forty-one years, the message has remained the same. Advancing the state of the art
demands results that are both visual and convincing. Making the case for new and improved materials requires
evidence that is both visual and convincing. And, as he continues to demonstrate
so
effectively, the execution
of his successful brand of microstructural design is stunningly
visual
and
convincing.
Happy birthday to very visual and convincing guy!
ACKNOWLEDGEMENTS
I
shall always be grateful to Gareth Thomas for accepting me into his group during the early summer
of
1972.
Thanks to my colleagues Prof. M.A. Meyers, Prof. R.O. Ritchie, and Prof. M. Sarikaya for their kind invitation
to contribute to this commemorative volume. Thanks also to the stalwart program managers at OBES in DOE

and ERDA before them who recognized the wisdom of microstructural design and funded this nation’s effort in
electron microscopy through all of these years.
REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Thomas, G., and Nutting,
J.
(1959-60)
J.
Inst. Metals
88,
81.
Nicholson, R.B., Thomas, G., andNutting,
J.
(1960)
ActaMet.

8,
172.
Thomas, G. (1964) “Process for Improving Strength and Corrosion Resistance of Aluminum
Alloys,” U.S. Patent
#
3,133,839.
Kikuchi,
S.
(1928)
Jupnn J. Phys.
5,
83.
Levine,
E.,
Bell, W.L., and Thomas, G. (1966)
J.
Appl. Phys.
37,2141.
Okamoto, P.R., Levine,
E.,
andThomas, G. (1967)J.
Appl. Phys.
38,289.
Okamoto, P.R., and Thomas,
G.
(1968)
Phys. Stat.
Sol.
25, 81.
Butler, E.P., and Thomas, G. (1970)

Acta Met.
18, 347.
Sinclair,
R.,
Gronsky, R., and Thomas, G. (1976)
Acfu Met.
24,789.
Shaw, T.M., and Thomas, G. (1978)
Science
202,625.
Gronsky, R., (1980) in
38th Annual Proc. Electron Microscopy SOC. Amer.,
G.W. Bailey (ed.), p 2.
Gronsky, R., and Thomas,
G.
(1983) in
41st Annual Proc. Electron Microscopy SOC. Amer.,
G.W.
Bailey (ed.), p. 310.
Zandbergen, H., Wang,
K.,
Gronsky, R., and Thomas, G. (1988)
Nature
331,596.
Thomas,
G.,
and Nakagawa, A. (1 986) “High Strength, Low Carbon, Dual Phase Steel Rods and
Wires and Process for Making Same,”
US.
Patent

#
4,613,385.
Thomas,
G.,
Johnson, S.M., and Dinger, T.R. (1989) “Method of Producing a Dense Refractory
Silicon Nitride Compact with One
or
More Crystalline Intergranular Phases,” U.S. Patent
#
4,830,800.
Bemardi,
J.J.,
Thomas,
G.,
and Heutten, A.R. (1999) “Giant Magnetoresistive Heterogeneous Alloys
and Method of Making Same.”
U.S.
Patent
#
5,882,436.
Nan0 and Microstructural Design
of
Advanced Materials
M.A. Meyers,
R.O.
Ritchie and M. Sarikaya (Editors)
0
2003
Published by Elsevier Ltd.
NANOCHEMICAL AND NANOSTRUCTURAL

STUDIES
OF
THE BRITTLE FAILURE
OF
ALLOYS
D.B. Williams’, M. Watanabe!, C. Li’ and
V.J.
Keast’
‘Department of Materials Science and Engineering and The Materials Research Center, Lehigh University,
Bethlehem PA 18015, USA
’Australian Key Centre for Microscopy and Microanalysis, Madsen Building University of Sydney, NSW
2006,
Australia
ABSTRACT
Controlling the brittle intergranular failure of metals and alloys requires understanding the structure and
chemistry of grain boundaries at the nanometer level or below. Recent developments in the analytical electron
microscope (AEM) permit such studies. It is now feasible to determine, in a single AEM specimen, the grain
boundary chemistry (using X-ray mapping), crystallographic characteristics (using automated crystallographic
analysis) and the localized bonding changes that may accompany segregation (using fine structure changes in
the electron energy
loss
spectrum). Computerized mapping techniques permit such information to be gained
from dozens of grain boundaries. Integration of this knowledge may permit the design of new alloys and new
heat treatments to create materials inherently resistant to the brittle failure often caused by nanometer level
grain boundary segregation of impurities and alloying elements.
INTRODUCTION
Gareth Thomas is primarily responsible for the development of the transmission electron microscope (TEM) as
the most versatile and integrated technique for the solution
of
materials problems. Throughout his long and

distinguished career Gareth has always stressed the essential need to use the TEM as one of a range
of
techniques to solve the problem at hand, rather than selecting a problem simply to suit the TEM’s capabilities.
Nevertheless, he has also pushed the development of the TEM to its fullest capabilities, particularly in the
exploration of its high-resolution imaging limits, embodied in the Atomic Resolution Microscope at the
National Center for Electron Microscopy at Berkeley. At Lehigh, we have taken a similar approach to attacking
materials problems, but emphasized the analytical side of the TEM, particularly elemental analysis via X-ray
and electron spectroscopy.
So
we can perhaps talk about “Microchemical Design of Advanced Materials” in this
article, in line with the theme of this book. This paper will review our implementation of Gareth’s philosophy to
the long-standing issue of brittle failure.
Brittle failure of metals and alloys remains a serious limitation to the development of new technologies and the
improvement of existing ones. The record of brittle failure studies starts in the 19‘h century [l] and has
encompassed classic examples such as the Titanic’s rivets
[2],
the Boston Molasses Tank
[3],
the
SS
Schenectady Liberty Ship
[4],
the Hinckley Point power-generation turbine [5] and the United Airlines DClO
11
12
D.B.
Williams
et
al.
crash at Sioux City

[6]
Despite such a long and painful history, the problem of bnttle failure remains as current
as ever in its societal effects For example, during 2001, the space shuttle fleet was grounded twice, first by the
discovery of cracking in the liquid hydrogen flow liners and second by beanng cracks in the crawlers that
transport the shuttles to the launch site Similarly, the high-speed Amtrak Acela trams were pulled out of service
following the discovery of cracks and breaks in brackets on the wheel sets of at least
8
of the
18
trains
Brittle failure in metals takes many forms, e g hydrogen embrittlement
[7,8],
temper embrittlement
[9],
environmental degradation
[
1
01 and associated stress-corrosion cracking
[
111,
fatigue failure
[
121, irradiation-
induced embnttlement
[
131,
liquid-metal embnttlement
[
141
and, more recently, such new phenomena as

quench embnttlement
[
151
Two key factors transcend this diverse array of failure phenomena, namely the role
of the grain boundary and segregation of undesirable elements to the boundary, as epitomized in Figure
1
There
is a long history of research relating the structure of the grain boundary to vanous properties, including the
tendency for segregation e g
[ 16,171
Some studies have shown correlations between individual grain-boundary
misonentation and the local chemistry, or related aspects such as grain-boundary precipitation
[18,19]
Such
correlations have been few and have rarely been carried out
on
undisturbed (I e non-fractured) grain boundanes
or
on enough grain boundanes to permit any statistical correlation to be inferred
In
general
it
has not proven
possible to relate directly the properties of grain boundanes
to
their structure While structure-property
correlations are very strong at the structural extremes of coherent twins
(C
=
3)

and random high-angle
boundaries
(C
>
-29), intermediate special boundaries (e g
C
=
5,
7,
9
etc
)
do not always correlate well with
properties Part of the reason for this is undoubtedly that the grain-boundary structure
is
not the pure elemental
construction that is commonly assumed, but is modified senously by local changes in the grain-boundary
chemistry The analytical
EM
(AEM) is uniquely configured to study these phenomena because
it
combines
high-resolution imaging, diffraction and nanometer-scale analysis of the same specimen at the same time,
permitting correlation of the grain-boundary structure, misonentation, chemistry and bonding
-
all at the
nanometer or sub-nanometer scale
No
other technique is
so

versatile at such a high resolution
At Lehigh, we have been using the
AEM
to correlate the chemistry, structure and bonding of embnttled grain
boundaries by a) performing quantitative analysis
of
nanometer-scale segregation to many grain boundanes
using X-ray mapping (XRM) via energy dispersive spectrometry (EDS),
b),
for those same grain boundanes,
determining their crystallographic misonentation via the latest computenzed diffraction techniques and c)
relating the occurrence of segregation to changes in the atomic bonding at the grain boundary via electron
energy-loss spectrometry
(EELS)
This paper gives an overview of the results of our integrated AEM studies in
model embnttling systems such as Cu Bi,
Cu-Sb
and Fe-P We will first introduce bnefly the techniques used
r
Figure
1:
SEM
images of the fracture surface of a) pure
Cu
and
b)
Cu
doped with
20
ppm

Bi