Livro - The Science and Design of Engineering Materials

Prévia do material em texto

pg001 7-27060 / IRWIN / Schaffer New page 1 ges 4-9-98 QC2
THE SCIENCE AND
DESIGN OF
ENGINEERING
MATERIALS
SECOND EDITION
......................................................................................................................... ........................................................................
pg front outside [V] G2 7-27060 / IRWIN / Schaffer MP
PHYSICAL DATA FOR THE ELEMENTS
Atomic Melting Density of Crystal
Atomic weight point solid, 20�C structure,
Element Symbol number (amu) (�C) (gm/cm3) 20�C
Aluminum Al 13 26.98 660.452 2.7 FCC
Antimony Sb 51 121.75 630.755 6.69 Rhomb.
Argon Ar 18 39.95 �189.352 — —
Arsenic As 33 74.92 603 5.78 Rhomb.
Barium Ba 56 137.33 729 3.59 BCC
Beryllium Be 4 9.012 1289 1.85 HCP
Boron B 5 10.81 2092 2.47 —
Bromine Br 35 79.9 �7.25 — —
Cadmium Cd 48 112.4 321.108 8.65 HCP
Calcium Ca 20 40.08 842 1.53 FCC
Carbon C 6 12.01 3826 2.27 Hex.
Cesium Cs 55 132.91 28.39 1.91 BCC
Chlorine Cl 17 35.45 �100.97 — —
Chromium Cr 24 52 1863 7.19 BCC
Cobalt Co 27 58.93 1495 8.8 HCP
Copper Cu 29 63.55 1084.87 8.93 FCC
Fluorine F 9 19 �219.67 — —
Gallium Ga 31 69.72 29.7741 5.91 Ortho.
Germanium Ge 32 72.59 938.3 5.32 Dia. cub.
Gold Au 79 196.97 1064.43 19.28 FCC
Helium He 2 4.003 �271.69 — —
Hydrogen H 1 1.008 �259.34 — —
Iodine I 53 126.9 113.6 4.95 Ortho.
Iridium Ir 77 192.22 2447 22.55 FCC
Iron Fe 26 55.85 1538 7.87 BCC
pg front inside [R] G1 7-27060 / IRWIN / Schaffer fr1
PHYSICAL DATA FOR THE ELEMENTS (Concluded)
Atomic Melting Density of Crystal
Atomic weight point solid, 20�C structure,
Element Symbol number (amu) (�C) (gm/cm3) 20�C
Lanthanum La 57 138.91 918 6.17 Hex.
Lead Pb 82 207.2 327.502 11.34 FCC
Lithium Li 3 6.941 180.6 0.533 BCC
Magnesium Mg 12 24.31 650 1.74 HCP
Manganese Mn 25 54.94 1246 7.47 Cubic
Mercury Hg 80 200.59 �38.836 — —
Molybdenum Mo 42 95.94 26.23 10.22 BCC
Neon Ne 10 20.18 �248.587 — —
Nickel Ni 28 58.71 1455 8.91 FCC
Niobium Nb 41 92.91 2469 8.58 BCC
Nitrogen N 7 14.01 �210.0042 — —
Oxygen O 8 16 �218.789 — —
Phosphorus P 15 30.97 44.14 1.82 Ortho.
Platinum Pt 78 195.09 1769 21.44 FCC
Potassium K 19 39.1 63.71 0.862 BCC
Silicon Si 14 28.09 1414 2.33 Dia. cub.
Silver Ag 47 107.87 961.93 10.5 FCC
Sodium Na 11 22.99 97.8 0.966 BCC
Sulfur S 16 32.06 115.22 2.09 Ortho.
Tin Sn 50 118.69 231.9681 7.29 BCT
Titanium Ti 22 47.9 1670 4.51 HCP
Tungsten W 74 183.85 3422 19.25 BCC
Uranium U 92 238.03 1135 19.05 Ortho.
Xenon Xe 54 131.3 �111.7582 — —
Zinc Zn 30 65.38 419.58 7.13 HCP
FM.iii 7-27060 / IRWIN / Schaffer js 3-31-98 ges 4-29 mp1
T H E A U T H O R S
James P. Schaffer
James P. Schaffer is an associate professor of Chemical Engineering at Lafayette College in Easton,
Pennsylvania. After receiving his B.S. in mechanical engineering (1981) and his M.S. (1982) and
Ph.D. (1985) in materials science and engineering from Duke University, he taught at the Georgia
Institute of Technology for five years before moving to Lafayette in 1990. He has taught an
introductory materials engineering course to more than 1200 undergraduate students using the
integrated approach taken in this text.
Dr. Schaffer’s field of research is the characterization of atomic scale defects in materials using
positron annihilation spectroscopy along with associated techniques. Professor Schaffer holds two
patents and has published more than 30 papers. He has received a number of teaching awards
including the Ralph R. Teetor Educational Award (SAE, 1989), Jones Lecture Award (Lafayette
College, 1994), Distinguished Teaching Award (Middle Atlantic Section of ASEE, 1996), Superior
Teaching Award (Lafayette Student Government, 1996), Marquis Distinguished Teaching Award
(Lafayette College, 1996), and the George Westinghouse Award (ASEE, 1998). He is a member of
ASEE, ASM International, TMS, Tau Beta Pi, and Sigma Xi.
Ashok Saxena
Ashok Saxena is currently professor and chair of the School of Materials Science and Engineering
at the Georgia Institute of Technology. Professor Saxena received his M.S. and Ph.D. degrees from
the University of Cincinnati in materials science and metallurgical engineering in 1972 and 1974,
respectively. After eleven years in industrial research laboratories, he joined Georgia Tech in 1985
as a professor of materials engineering. He assumed the chairmanship of the school in 1993. From
1991 to 1994, he also served as the director of the Campus-Wide Composites Education and
Research Center.
Dr. Saxena’s primary research area is mechanical behavior of materials, in which he has
published over 125 scientific papers and has edited several books. His research in the area of creep
and creep-fatigue crack growth has won international acclaim; he was awarded the 1992 George
Irwin Medal for it by ASTM. He is also the recipient of the 1994 ASTM Award of Merit. Professor
Saxena is an ASTM Fellow, a Fellow of ASM International, and a member of ASEE, TMS, Sigma
Xi, and Alpha Sigma Mu.
Stephen D. Antolovich
Stephen D. Antolovich is currently a professor of Mechanical and Materials Engineering at Wash-
ington State University, where he also serves as director of the School of Mechanical and Materials
Engineering. He received his B.S. and M.S. in metallurgical engineering from the University of
Wisconsin in 1962 and 1963, respectively, and a Ph.D. in materials science from the University of
California–Berkeley in 1966. He joined the Georgia Institute of Technology in 1983, where he
served as professor of materials engineering, director of the Mechanical Properties Research
Laboratory (MPRL), and director of the School of Materials Science and Engineering.
iii
FM.iv 7-27060 / IRWIN / Schaffer js 3-31-98 ges 4-29 mp1
iv The Authors
In 1988 Dr. Antolovich was presented with the Reaumur Medal from the French Metallurgical
Society. In 1989 he was named Professeur Invite by CNAM University in Paris. In 1990 he was
presented with the Nadai Award by the ASME. Dr. Antolovich regularly makes presentations to
learned societies in the United States, Europe, Canada, and Korea and has carried out funded
research/consultation for numerous government agencies. Dr. Antolovich has published over 100
archival articles in leading technical journals. His major research interests are in the areas of
deformation, fatigue, and fracture, especially at high temperatures. He is a member of ASME, ASTM,
and AIME, and a Fellow Member of ASM International.
Thomas H. Sanders, Jr.
Thomas H. Sanders, Jr., is currently Regents’ Professor in the School of Materials Science and
Engineering at the Georgia Institute of Technology. Professor Sanders received his B.S. and M.S.
in ceramic engineering from Georgia Tech in 1966 and 1969, respectively. In 1974 he completed
his research for his Ph.D in metallurgical engineering at Georgia Tech and joined the Physical
Metallurgy Division of Alcoa Technical Center, Alcoa Center, Pennsylvania. While at Alcoa
Center his major research efforts were directed toward developing and implementing processing
microstructure–properties relationships for high-strength aluminum alloys used in aerospace appli-
cations. He was on the faculty in Materials Science and Engineering at Purdue University from
1980 to 1986 and joined the faculty at Georgia Tech in 1987. He was awarded the W. Roane Beard
Outstanding Teacher Award for 1994.
Dr. Sanders’s primary research area is physical metallurgy of materials with primary emphasis
on aluminum alloys. He has published approximately 100 scientific papers and has edited several
books. He was awarded a Fulbright grant in 1992 to conduct research at Centre National de la
Recherche Scientifique (ONERA), Chaˆtillon, France. Professor Sanders is a member of TMS and
a Fellow of ASM.
Steven B. Warner
Steven B. Warner is Professor and Chairperson of the Textile Sciences Department, University of
Massachusetts, Dartmouth. Dr. Warner earned hiscombined S.B. and S.M. degrees in metallurgy
and ceramics in 1973 from the Massachusetts Institute of Technology. In 1976 he was awarded an
Sc.D. from the Department of Materials Science and Engineering at MIT. He was a research
scientist from 1976–1982 at Celanese Research Co. and from 1982–1988 at Kimberly-Clark Corp.
In 1987 he joined Georgia Institute of Technology as Adjunct Professor in Chemical Engineering;
in 1988 he became Associate Professor in Materials Engineering; and from 1990–1994 he was a
faculty member in Textile and Fiber Engineering.
Dr. Warner’s research interests are the structure-property relationships of materials, especially
polymers. He has published more than 30 scientific papers, holds six U.S. patents, and is the author
of Fiber Science. In addition he has been a technical expert in a number of patent cases.
pg v [R] G7 7-27060 / IRWIN / Schaffer ges 4-29 MP1 FR1
F O R E W A R D
If one’s technical library were to contain only a single book on materials, this is the book
to have. The authors have succeeded in covering the field of materials science and
engineering in even its broadest aspects. They have captured both the science of the
discipline as well as the engineering and design of materials. All classes of materials are
treated; metals, semiconductors, ceramics, and polymers, as well as composites made of
combinations of these. As urged in the National Research Council’s recent study of
materials science and engineering, processing and synthesis also are included, as are the
subjects of machinability and joining. (No material, however outstanding its properties,
is likely to be very useful if it can’t be produced, shaped, or attached to other compo-
nents.)
The breadth of The Science and Design of Engineering Materials, which reflects the
varied fields of expertise of the authors, makes it an ideal text for a survey course for
students from all fields of engineering. Because of the depth as well as the breadth with
which the topics are treated, the text also is an excellent choice for introductory courses
for materials science and engineering majors. Graduates of these introductory and survey
classes will value The Science and Design of Engineering Materials as a resource book
for years to come. The clear explanations and frequent examples allow the practicing
engineer, on his or her own, to become acquainted with the materials field or update
his/her knowledge of it. Care and skill have been exercised in the choice of illustrations.
Numerous drawings and graphs augment explanations in the text, and clearly reproduced
micrographs provide real-life examples of the phenomena being described. The examples
and questions are especially noteworthy. While a portion of the questions are of the “one
right answer” kind, and are intended to reinforce and clarify the material in the text, others
are of the open-ended, design type that require creative thought and more closely resem-
ble real-life situations. They can form the bases for useful and provocative class discus-
sions.
This new edition of The Science and Design of Engineering Materials is a valuable
addition to the materials literature. It will contribute to the materials education of engi-
neers and scientists for years to come.
Julia Weertman
Walter P. Murphy Professor of Materials Science and Engineering
Northwestern University
v
pg027 [R] G7 7-27060 / IRWIN / Schaffer pgm 11-23-96 R0
P R E F A C E
A society’s ability to develop and use materials is a measure of both its technical sophis-
tication and its technological future. This book is devoted to helping all engineers better
understand and use materials to ensure the future of technology.
THE INTENDED MARKET
The book is intended for undergraduate students from all engineering disciplines. It
assumes a minimal background in calculus, chemistry, and physics at the first-year college
level. The text has been used successfully in a variety of situations including:
� A traditional 40- to 42-lecture single-semester/quarter course
� A yearlong course sequence
� A foundation course for materials engineering majors
� A service course with students from multiple engineering disciplines
� A service course targeted at a specific audience (for mechanical or electrical
engineers only)
� A section composed of only first- and second-year students
� As a refresher course for materials engineering graduate students with a B.S.
degree in another engineering discipline.
Though only some of the chapters might be used in a single-semester/quarter course,
experience suggests that students benefit from reading the entire text. The authors have
intentionally made no effort to mark optional sections or chapters, since topic selection
is a function of many factors, including instructor preferences, the background and needs
of the students, and the course sequence at a specific institution.
THE AUTHOR TEAM
The field of materials engineering is so vast that no single individual can master it all.
Therefore, a team was assembled with expertise in ceramics, composites, metals, poly-
mers, and semiconductors. The author team has the collective expertise to explain clearly
all the important aspects of the field in a single coherent package. The authors teach or
have taught in chemical, materials, mechanical, and textile engineering departments. We
teach at small colleges, where the engineering program is within a liberal arts setting, as
well as major technological universities. Just as a composite combines the best features of
its constituent materials, this book combines the varied strengths of its authors.
vii
fm.viii 7-27060 / IRWIN / Schaffer js 4-9-98 QC1
viii Preface
THE INTEGRATED APPROACH
The book is organized into four parts. Part I, Fundamentals, focuses on the structure of
engineering materials. Important topics include atomic bonding, thermodynamics and
kinetics, crystalline and amorphous structures, defects in crystals, and strength of crys-
tals. The concepts developed in these six chapters provide the foundation for the remain-
der of the course. In Part II, Microstructural Development, the important processing
variables of temperature, composition, and time are introduced, along with methods for
controlling the structure of a material on the microscopic level. Part III focuses on the
engineering properties of the various classes of materials. It builds upon the understanding
of structure developed in Part I and the methods used to control structure set forth in
Part II. It is in the properties section of the text that our approach, termed the integrated
approach, differs from that of most of the competing texts.
Traditionally, all the macroscopic properties of one type of material (usually metals)
are discussed before moving on to describe the properties of a second class of materials.
The process is then repeated for ceramics, polymers, composites, and semiconductors.
This traditional progression offers several advantages, including the ability to stress the
unique strengths and weaknesses of each material class.
As authors, we believe most engineers will be searching for a material that can fulfill
a specific list of properties as well as economic, processing, and environmental require-
ments and will want to consider all classes of materials. That is, most engineers are more
likely to “think” in terms of a property class rather than a material class. Thus, we describe
the mechanical properties of all classes of materials, then the electrical properties of all
classes of materials, and so on. We call this the integrated approach because it stresses
fundamental concepts applicable to all materials first, and then points out the unique
characteristics of each material class. During the development of the book the authors
found that there were times when “forcing integration” would have degraded the quality
of the presentation.Therefore, there are sections of the text where the integrated approach
is temporarily suspended to improve clarity and emphasize the unique characteristics of
specific materials.
The fourth and final part of the book deals with processing methods and with the
overall materials design and selection process. These two chapters tie together all the
topics introduced in the first three parts of the book. The goal is for the student to
understand the methods used to select the appropriate material and processing methods
required to satisfy a strict set of design specifications.
EMPHASIS ON DESIGN AND APPLICATIONS
Students are better able to understand the theoretical aspects of materials science and
engineering when they are continually reinforced with applications and examples from
their personal experiences. Thus, we have made a substantial effort to include both
familiar and technologically important applications of every concept introduced in the
text. In many cases we begin a discussion of a topic by describing a familiar situation and
asking why certain results occur. This approach motivates the students to learn the details
of the quantitative models so that they can solve problems, or understand phenomena, in
which they have a personal interest.
The authors believe that most engineering problems have multiple correct solutions
and must include environmental, ethical, and economic considerations. Therefore, our
homework problems include both numerical problems with a single correct answer and
design problems with multiple valid solution techniques and “correct” answers. The
fm. ix 7-27060 / IRWIN / Schaffer js 4-9-98 QC1 ges 4-29 mp1
Preface ix
sample exercises within the text are divided into two classes. The Examples are straightfor-
ward applications of concepts and equations in the text and generally have a single correct
numerical solution. In contrast, Design Examples are open-ended and often involve select-
ing a material for a specific application.
We have used a Case Study involving the design of a camcorder as a continuous thread
throughout the manuscript. Each of the four parts of the text—Fundamentals, Microstruc-
tural Development, Properties, and Design—begins with the identification of several mate-
rials issues associated with the camcorder that can only be understood using concepts
developed in that portion of the text. This technique allows students to get a view of the
forest before they begin to focus on individual trees. The ongoing case also permits us to
form bridges between the important aspects of the course within a context that is familiar
to most students.
The authors’ belief in the importance of materials design and selection is underscored by
the inclusion of an entire chapter on this subject at the end of the book. We recommend
strongly that the instructor have the students read this chapter even if the schedule does not
permit its inclusion in lecture. We find that it “closes the loop” for many of our students by
helping them to understand the relationships among the many and varied topics introduced
in the text. The design chapter contains 10 case studies and addresses issues such as
life-cycle cost analysis, material and process selection, nuclear waste disposal, inspection
criteria, failure analysis, and risk assessment and product liability.
CHANGES TO THE SECOND EDITION
Five new features have been added to the second edition of the text:
1. Each chapter begins with a motivational insert called Materials in Action. This
feature is designed to introduce the reader to the important ideas in the chapter through
an interesting real-world situation. Examples include a description of how adding 0.4
weight percent carbon to iron increases the strength of the material by two orders of
magnitude, a discussion of why directionally solidified nickel-based turbine blades are
worth their weight in gold in some aerospace applications, and an illustration of the false
economy of using less expensive machining operations if they have a negative influence
on fatigue crack initiation. This new feature extends our emphasis on design and applica-
tions, which was one of the most popular attractions of the first edition.
2. We have developed a new Materials in Focus CD-ROM to enhance the textbook
presentation. The CD-ROM contains a phase diagram tool and over 30 animations
designed to help the reader gain an understanding of some of the visual concepts in the
book. Examples include “three-dimensional” views of unit cells and polymer molecules,
the movement of dislocations through crystals, changes in the population of electron
energy levels in semiconductors with temperature, illustrations of polarization mecha-
nisms, and examples of processing operations. In addition, the CD-ROM contains all of
the photomicrographs in the text, and a series of interactive example problems. For
example, in the portions of Chapter 7 on phase diagrams students can select a state point
on a phase diagram and have the software help them determine the phases present, the
compositions of the phases, and their relative amounts. Every illustration on the CD-
ROM is directly linked to an illustration, concept, or problem in the text. In fact, every
location in the text that has a link to a CD-ROM animation or example is clearly indicated
by the presence of a “CD-ROM” icon in the margin of the text.
fm.10 7-27060 / IRWIN / Schaffer js 4-9-98 QC1 ges 4-29 MP2
x Preface
3. Over 225 new homework problems have been added throughout the text. The
majority of the chapters contain several design problems (i.e., problems with multiple
correct solutions). These homework problems are marked with a “Design Problem” icon
in the margin of the text.
4. We have added an eight-page full color insert near the center of the book. This
feature allows us to illustrate several important applications of materials science and
engineering that simply are not easily described with either words or two-color illustra-
tions.
5. The entire book has been redesigned for enhanced readability. In particular, the use
of the icons illustrated below permits the reader to quickly identify several important
features of the second edition:
ADesign Problems
ADesign Examples
AAnimated CD-ROM Concept
We have made a determined effort to improve the quality of the photomicrographs and
to eliminate errors that were present in the first edition. We would like to express our
sincere thanks to those of you who spotted problems and pointed them out to us. The book
is better for your efforts, and if you have additional suggestions for how to improve the
text we would be happy to hear them.
6. A Web site for the book can be found at http://www.mhhe.com. It contains infor-
mation about the book and its supplements, Web links, and teaching resources.
ACKNOWLEDGMENTS
This book has undergone extensive revision under the direction of a distinguished panel
of colleagues who have served as reviewers. The book has been greatly improved by this
process and we owe each reviewer a sincere debt of gratitude. The reviewers for the first
edition were:
John R. Ambrose, University of Florida
Robert Baron, Temple University
Ronald R. Bierderman, Worcester Polytechnic Institute
Samuel A. Bradford, University of Alberta
George L. Cahen, Jr., University of Virginia
Stephen J. Clarson, University of Cincinnati
Diana Farkas, Virginia Polytechnic Institute
David R. Gaskell, Purdue University
A. Jeffrey Giacomin, Texas A&M University
Charles M. Gilmore, The George Washington University
David S. Grummon, Michigan State University
Ian W. Hall, University of Delaware
Craig S. Hartley, University of Alabama at Birmingham
fm.11 7-27060 / IRWIN / Schaffer js 4-9-98 QC1 ges 4-29 MP2
Preface xi
Phillip L. Jones, Duke University
Dae Kim, The Ohio State University
David B. Knorr, RensselaerPolytechnic Institute
D. Bruce Masson, Washington State University
John C. Matthews, Kansas State University
Masahiro Meshii, Northwestern University
Robert W. Messler, Jr., Rensselaer Polytechnic Institute
Derek O. Northwood, University of Windsor
Mark R. Plichta, Michigan Technological University
Richard L. Porter, North Carolina State University
John E. Ritter, University of Massachusetts
David A. Thomas, Lehigh University
Peter A. Thrower, Pennsylvania State University
Jack L. Tomlinson, California State Polytechnic University
Alan Wolfenden, Texas A&M University
Ernest G. Wolff, Oregon State University
The reviewers for the second edition are:
Bezad Bavarian, California State University–Northridge
David Cahill, University of Illionois
Stephen Krause, Arizona State University
Hillary Lackritz, Purdue University
Thomas J. Mackin, University of Illinois–Urbana
Arumugam Manthiram, The University of Texas at Austin
Walter W. Milligan, Michigan Technological University
Monte J. Pool, University of Cincinnati
Suzanne Rohde, University of Nebraska–Lincoln
Jay Samuel, University of Wisconsin–Madison
Shome N. Sinha, University of Illinois–Chicago
The authors would also like to thank the members of the editorial team: Tom Casson,
publisher; Scott Isenberg; Kelley Butcher, developmental editor; and Gladys True, project
manager. We would also like to thank James Mohler of the Department of Technical
Graphics, Purdue University, the developer of the Materials in Focus CD-ROM.
SUPPLEMENTS
We have devoted considerable effort to the preparation of a high-quality solutions manual.
Our approach is to employ a common solution technique for every homework problem.
The procedure includes the following steps:
1. Find: (What are you looking for?)
2. Given: (What information is supplied in the problem statement?)
3. Data: (What additional information is available, from tables, figures, or
equations in the text, and is required to solve this problem?)
FM’12 7-27060 / IRWIN / Schaffer js 3-31-9 8
xii Preface
4. Assumptions: (What are the limits on this analysis?)
5. Sketch: (What geometrical information is required?)
6. Solution: (A detailed step-by-step procedure.)
7. Comments: (How can this solution be applied to other similar situations and
what alternative solution techniques might be appropriate?)
The solutions manual is available to adopters of the text. Also, the authors have gained
considerable experience using the “integrated” approach in the classroom and are avail-
able to discuss implementation strategies with interested colleagues at other institutions.
James P. Schaffer Thomas H. Sanders, Jr.
Ashok Saxena Steven B. Warner
Stephen D. Antolovich
FM.xv 7-27060 / IRWIN / Schaffer js 4-9-98 QC1
1 MATERIALS SCIENCE AND ENGINEERING 2
1.1 Introduction 4
1.2 The Role of Materials in Technologically
Advanced Societies 4
1.3 The Engineering Profession and
Materials 6
1.4 Major Classes of Materials 7
1.4.1 Metals 8
1.4.2 Ceramics 9
1.4.3 Polymers 10
1.4.4 Composites 11
1.4.5 Semiconductors 13
1.5 Materials Properties and Materials
Engineering 14
1.6 The Integrated Approach to Materials
Engineering 16
1.7 Engineering Professionalism and
Ethics 18
Summary 19
PART I FUNDAMENTALS 20
2 ATOMIC SCALE STRUCTURES 22
2.1 Introduction 24
2.2 Atomic Structure 24
2.3 Thermodynamics and Kinetics 28
2.4 Primary Bonds 30
2.4.1 Ionic Bonding 31
2.4.2 Covalent Bonding 34
2.4.3 Metallic Bonding 35
2.4.4 Influence of Bond Type on Engineering
Properties 37
2.5 The Bond-Energy Curve 39
2.6 Atomic Packing and Coordination
Numbers 43
2.7 Secondary Bonds 49
2.8 Mixed Bonding 51
2.9 The Structure of Polymer Molecules 52
Summary 54
Key Terms 55
Homework Problems 56
C O N T E N T S
3 CRYSTAL STRUCTURES 60
3.1 Introduction 62
3.2 Bravais Lattices and Unit Cells 62
3.3 Crystals with One Atom per Lattice Site and
Hexagonal Crystals 65
3.3.1 Body-Centered Cubic Crystals 65
3.3.2 Face-Centered Cubic Crystals 68
3.3.3 Hexagonal Close-Packed
Structures 69
3.4 Miller Indices 71
3.4.1 Coordinates of Points 72
3.4.2 Indices of Directions 73
3.4.3 Indices of Planes 76
3.4.4 Indices in the Hexagonal System 77
3.5 Densities and Packing Factors of Crystalline
Structures 78
3.5.1 Linear Density 78
3.5.2 Planar Density 80
3.5.3 Volumetric Density 82
3.5.4 Atomic Packing Factors and Coordination
Numbers 82
3.5.5 Close-Packed Structures 83
3.6 Interstitial Positions and Sizes 85
3.6.1 Interstices in the FCC Structure 85
3.6.2 Interstices in the BCC Structure 86
3.6.3 Interstices in the HCP Structure 87
3.7 Crystals with Multiple Atoms per Lattice
Site 87
3.7.1 Crystals with Two Atoms per Lattice
Site 88
3.7.2 Crystals with Three Atoms per Lattice
Site 92
3.7.3 Other Crystal Structures 93
3.8 Liquid Crystals 95
3.9 Single Crystals and Polycrystalline
Materials 95
3.10 Allotropy and Polymorphism 96
3.11 Anisotropy 98
3.12 X-ray Diffraction 98
Summary 103
Key Terms 104
Homework Problems 104
xv
FM.xvi 7-27060 / IRWIN / Schaffer js 4-9-98 QC1 ges 4-29 mp1 FR1
xvi Contents
4 POINT DEFECTS AND DIFFUSION 110
4.1 Introduction 112
4.2 Point Defects 112
4.2.1 Vacancies and Interstitials in
Crystals 112
4.2.2 Vacancies and Interstitials in lonic
Crystals 115
4.3 Impurities 116
4.3.1 Impurities in Crystals 117
4.3.2 Impurities in lonic Crystals 121
4.4 Solid-State Diffusion 122
4.4.1 Practical Examples of Diffusion 123
4.4.2 A Physical Description of Diffusion
(Fick’s First Law) 124
4.4.3 Mechanisms of Diffusion in Covalent
and Metallic Crystals 128
4.4.4 Diffusion for Different Levels of
Concentration 130
4.4.5 Mechanisms of Diffusion in Ionic
Crystals 132
4.4.6 Mechanisms of Diffusion in
Polymers 133
4.4.7 Fick’s Second Law 135
Summary 140
Key Terms 141
Homework Problems 141
5 LINEAR, PLANAR, AND VOLUME DEFECTS 146
5.1 Introduction 148
5.2 Linear Defects, Slip, and Plastic
Deformation 148
5.2.1 The Shear Strength of Deformable
Single Crystals 148
5.2.2 Slip in Crystalline Materials and Edge
Dislocations 152
5.2.3 Other Types of Dislocations 156
5.2.4 Slip Planes and Slip Directions in
Metal Crystals 159
5.2.5 Dislocations in Ionic, Covalent, and
Polymer Crystals 162
5.2.6 Other Effects of Dislocations on
Properties 166
5.3 Planar Defects 167
5.3.1 Free Surfaces in Crystals 167
5.3.2 Grain Boundaries in Crystals 168
5.3.3 Grain Size Measurement 169
5.3.4 Grain Boundary Diffusion 170
5.3.5 Other Planar Defects 171
5.4 Volume Defects 173
5.5 Strengthening Mechanisms in Metals 174
5.5.1 Alloying for Strength 175
5.5.2 Strain Hardening 176
5.5.3 Grain Refinement 178
5.5.4 Precipitation Hardening 179
Summary 179
Key Terms 180
Homework Problems 180
6 NONCRYSTALLINE AND SEMICRYSTALLINE
MATERIALS 184
6.1 Introduction 186
6.2 The Glass Transition Temperature 186
6.3 Viscous Deformation 190
6.4 Structure and Properties of Amorphous and
Semicrystalline Polymers 192
6.4.1 Polymer Classification 192
6.4.2 Molecular Weight 198
6.4.3 Polymer Conformations and
Configurations 200
6.4.4 Factors Determining Crystallinity of
Polymers 202
6.4.5 Semicrystalline Polymers 205
6.4.6 The Relationship between Structure
and Tg 206
6.5 Structure and Properties of Glasses 206
6.5.1 Ionic Glasses 208
6.5.2 Covalent Glasses 211
6.5.3 Metallic Glasses 212
6.6 Structure and Properties of Rubbers and
Elastomers 212
6.6.1 Thermoset Elastomers 213
6.6.2 Thermoplastic Elastomers 214
6.6.3 Crystallization in Rubbers 215
6.6.4 Temperature Dependence of Elastic
Modulus 216
6.6.5 Rubber Elasticity 217
Summary 219
Key Terms 220
Homework Problems 220
PART II MICROSTRUCTURAL DEVELOPMENT 224
7 PHASE EQUILIBRIA AND PHASE
DIAGRAMS 226
7.1 Introduction 228
7.2 The One-Component Phase Diagram229
7.3 Phase Equilibria in a Two-Component
System 232
7.3.1 Specification of Composition 232
7.3.2 The Isomorphous Diagram for Ideal
Systems 234
7.3.3 Phases in Equilibrium and the Lever
Rule 235
FM.xvii 7-27060 / IRWIN / Schaffer js 4-9-98 QC1 ges 4-29 mp1
Contents xvii
7.3.4 Solidification and Microstructure of
Isomorphous Alloys 238
7.3.5 Determination of Liquidus and Solidus
Boundaries 241
7.3.6 Specific Isomorphous Systems 242
7.3.7 Deviations from Ideal Behavior 242
7.4 The Eutectic Phase Diagram 247
7.4.1 Definitions of Terms in the Eutectic
System 248
7.4.2 Melting and Solidification of Eutectic
Alloys 249
7.4.3 Solidification of Off-Eutectic Alloys 250
7.4.4 Methods Used to Determine a Phase
Diagram 255
7.4.5 Phase Diagrams Containing Two
Eutectics 257
7.5 The Peritectic Phase Diagram 260
7.6 The Monotectic Phase Diagram 263
7.7 Complex Diagrams 265
7.8 Phase Equilibria Involving Solid-to-Solid
Reactions 267
7.8.1 Eutectoid Systems 268
7.9 Phase Equilibria in Three-Component
Systems 271
7.9.1 Plotting Compositions on a Ternary
Diagram 272
7.9.2 The Lever Rule in Ternary Systems 274
Summary 275
Key Terms 276
Homework Problems 277
8 KINETICS AND MICROSTRUCTURE OF
STRUCTURAL TRANSFORMATIONS 286
8.1 Introduction 288
8.2 Fundamental Aspects of Structural
Transformations 289
8.2.1 The Nature of a Phase
Transformation 289
8.2.2 The Driving Force for a Phase
Change 290
8.2.3 Homogeneous Nucleation of a
Phase 292
8.2.4 Heterogeneous Nucleation of a
Phase 296
8.2.5 Matrix/Precipitate Interfaces 298
8.2.6 Growth of a Phase 302
8.3 Applications to Engineering Materials 304
8.3.1 Phase Transformations in Steels 305
8.3.2 Precipitation from a Supersaturated
Solid Solution 320
8.3.3 Solidification and Homogenization of
an Alloy 324
8.3.4 Recovery and Recrystallization
Processes 330
8.3.5 Sintering 334
8.3.6 Martensitic (Displacive)
Transformations in Zirconia 337
8.3.7 Devitrification of an Oxide Glass 339
8.3.8 Crystallization of Polymers 340
Summary 343
Key Terms 344
Homework Problems 344
PART III PROPERTIES 356
9 MECHANICAL PROPERTIES 358
9.1 Introduction 360
9.2 Deformation and Fracture of Engineering
Materials 360
9.2.1 Elastic Deformation 361
9.2.2 Deformation of Polymers 364
9.2.3 Plastic Deformation 367
9.2.4 Tensile Testing 368
9.2.5 Strengthening Mechanisms 376
9.2.6 Ductile and Brittle Fracture 377
9.2.7 Hardness Testing 378
9.2.8 Charpy Impact Testing 382
9.3 Brittle Fracture 386
9.3.1 Examples and Sequence of Events
Leading to Brittle Fracture 386
9.3.2 Griffith-Orowan Theory for Predicting
Brittle Fracture 388
9.4 Fracture Mechanics: A Modern Approach 390
9.4.1 The Stress Intensity Parameter 391
9.4.2 The Influence of Sample Thickness 393
9.4.3 Relationship between Fracture
Toughness and Tensile Properties 394
9.4.4 Application of Fracture Mechanics to
Various Classes of Materials 395
9.4.5 Experimental Determination of Fracture
Toughness 398
9.5 Fatigue Fracture 399
9.5.1 Definitions Relating to Fatigue
Fracture 399
9.5.2 Fatigue Testing 401
9.5.3 Correlations between Fatigue Strength
and Other Mechanical Properties 402
9.5.4 Microscopic Aspects of Fatigue 404
9.5.5 Prevention of Fatigue Fractures 406
9.5.6 A Fracture Mechanics Approach to
Fatigue 406
9.6 Time-Dependent Behavior 409
9.6.1 Environmentally Induced Fracture 409
9.6.2 Creep in Metals and Ceramics 410
FM.xviii 7-27060 / IRWIN / Schaffer js 4-9-98 QC1
xviii Contents
9.6.3 Mechanisms of Creep
Deformation 412
Summary 416
Key Terms 417
Homework Problems 418
10 ELECTRICAL PROPERTIES 426
10.1 Introduction 428
10.2 Electrical Conduction 428
10.2.1 Charge per Carrier 432
10.2.2 Charge Mobility 433
10.2.3 Energy Band Diagrams and Number
of Charge Carriers 436
10.2.4 The Influence of Temperature on
Electrical Conductivity and the
Fermi-Dirac Distribution
Function 438
10.2.5 Conductors, Semiconductors, and
Insulators 444
10.2.6 Ionic Conduction Mechanisms 449
10.2.7 Effects of Defects and
Impurities 451
10.2.8 Conducting Polymers 453
10.2.9 Superconductivity 454
10.2.10 Devices and Applications 456
10.3 Semiconductors 457
10.3.1 Intrinsic and Extrinsic
Conduction 457
10.3.2 Compound Semiconductors 464
10.3.3 Role of Defects 464
10.3.4 Simple Devices 465
10.3.5 Microelectronics 470
Summary 472
Key Terms 473
Homework Problems 473
11 OPTICAL AND DIELECTRIC PROPERTIES 478
11.1 Introduction 480
11.2 Polarization 481
11.2.1 Electronic Polarization 481
11.2.2 Ionic Polarization 482
11.2.3 Molecular Polarization 483
11.2.4 Interfacial Polarization 484
11.2.5 Net Polarization 484
11.2.6 Applications 485
11.3 Dielectric Constant and Capacitance 487
11.3.1 Capacitance 487
11.3.2 Permittivity and Dielectric
Constant 487
11.3.3 Dielectric Strength and
Breakdown 490
11.4 Dissipation and Dielectric Loss 492
11.5 Refraction and Reflection 494
11.5.1 Refraction 495
11.5.2 Specular Reflection 496
11.5.3 Dispersion 499
11.5.4 Birefringence 499
11.5.5 Application: Optical
Waveguides 500
11.6 Absorption, Transmission, and
Scattering 502
11.6.1 Absorption 502
11.6.2 Absorption Coefficient 504
11.6.3 Absorption by Chromophores 505
11.6.4 Scattering and Opacity 507
11.7 Electronic Processes 508
11.7.1 X-Ray Fluorescence 508
11.7.2 Luminescence 508
11.7.3 Phosphorescence 510
11.7.4 Thermal Emission 510
11.7.5 Photoconductivity 510
11.7.6 Application: Lasers 511
Summary 512
Key Terms 513
Homework Problems 513
12 MAGNETIC PROPERTIES 518
12.1 Introduction 520
12.2 Materials and Magnetism 520
12.3 Physical Basis of Magnetism 521
12.4 Classification of Magnetic Materials 523
12.5 Diamagnetism and Paramagnetism 523
12.6 Ferromagnetism 525
12.6.1 Magnetic Domains 526
12.6.2 Response of Ferromagnetic Materials
to External Fields 528
12.6.3 The Shape of the Hysteresis
Loop 530
12.6.4 Microstructural Effects 531
12.6.5 Temperature Effects 531
12.6.6 Estimating the Magnitude of M 531
12.7 Antiferromagnetism and
Ferrimagnetism 532
12.8 Devices and Applications 535
12.8.1 Permanent Magnets 535
12.8.2 Transformer Cores 538
12.8.3 Magnetic Storage Devices 539
12.9 Superconducting Magnets 541
Summary 543
Key Terms 543
Homework Problems 544
13 THERMAL PROPERTIES 548
13.1 Introduction 550
13.2 Coefficient of Thermal Expansion 550
FM.xix 7-27060 / IRWIN / Schaffer js 3-31-98 ges 4-29 mp1
Contents xix
13.3 Heat Capacity 554
13.4 Thermal Conduction Mechanisms 557
13.5 Thermal Stresses 562
13.6 Applications 566
13.6.1 Bimetallic Strip 566
13.6.2 Thermal Insulation 567
13.6.3 Thermal Shock–Resistant
Cookware 567
13.6.4 Tempered Glass 567
13.6.5 Support Structure for Orbiting
Telescopes 569
13.6.6 Ceramic-to-Metal Joints 569
13.6.7 Cryogenic Materials 570
Summary 571
Key Terms 571
Homework Problems 571
14 COMPOSITE MATERIALS 576
14.1 Introduction 578
14.2 History and Classification of Composites 578
14.3 General Concepts 582
14.3.1 Strengthening by Fiber
Reinforcement 582
14.3.2 Characteristics of Fiber
Materials 583
14.3.3 Characteristics of Matrix
Materials 588
14.3.4 Role of Interfaces 589
14.3.5 Fiber Architecture 590
14.3.6 Strengthening in Aggregate
Composites 592
14.4 Practical Composite Systems 593
14.4.1 Metal-Matrix Composites 593
14.4.2 Polymer-Matrix Composites 593
14.4.3 Ceramic-Matrix Composites 594
14.4.4 Carbon-Carbon Composites 595
14.5 Prediction of Composite Properties 595
14.5.1 Estimation of Fiber Diameter, Volume
Fraction, and Density of the
Composite 596
14.5.2 Estimation of Elastic Modulus and
Strength 596
14.5.3 Estimation of the Coefficient of
Thermal Expansion 600
14.5.4 Fracture Behavior of Composites 601
14.5.5 Fatigue Behavior of Composites 602
14.6 Other Applications of Composites 604
14.6.1Estimation of Nonmechanical
Properties of Composites 606
Summary 607
Key Terms 607
Homework Problems 608
15 MATERIALS-ENVIRONMENT
INTERACTIONS 612
15.1 Introduction 614
15.2 Liquid-Solid Reactions 614
15.2.1 Direct Dissolution Mechanisms 616
15.2.2 Electrochemical Corrosion—Half-Cell
Potentials 619
15.2.3 Kinetics of Corrosion Reactions 626
15.2.4 Specific Types of Corrosion 629
15.2.5 Corrosion Prevention 640
15.3 Direct Atmospheric Attack (Gas-Solid
Reactions) 643
15.3.1 Alteration of Bond Structures by
Atmospheric Gases 644
15.3.2 Formation of Gaseous Reaction
Products 646
15.3.3 Protective and Nonprotective Solid
Oxides 646
15.3.4 Kinetics of Oxidation 649
15.3.5 Using Atmospheric “Attack” to
Advantage 652
15.3.6 Methods of Improving Resistance to
Atmospheric Attack 653
15.4 Friction and Wear (Solid-Solid
Interactions) 655
15.4.1 Wear Mechanisms 655
15.4.2 Designing to Minimize Friction and
Wear 658
15.5 Radiation Damage 658
Summary 660
Key Terms 661
Homework Problems 661
PART IV MATERIALS SYNTHESIS AND DESIGN 666
16 MATERIALS PROCESSING 668
16.1 Introduction 670
16.2 Process Selection Criteria and
Interrelationship among Structure,
Processing, and Properties 670
16.3 Casting 671
16.3.1 Metal Casting 671
16.3.2 Casting of Ceramics 676
16.3.3 Polymer Molding 676
16.4 Forming 679
16.4.1 Metal Forming 679
Case Study: Process Selection for a Steel
Plate 680
16.4.2 Forming of Polymers 686
16.4.3 Forming of Ceramics and
Glasses 687
16.5 Powder Processing 689
FM.xx 7-27060 / IRWIN / Schaffer ges 4-9-98 QC2 FR1
xx Contents
16.5.1 Powder Metallurgy 689
Case Study: Specification of Powder Size
Distribution for Producing Steel
Sprockets 691
16.5.2 Powder Processing of Ceramics 692
16.6 Machining 692
16.7 Joining Processes 694
16.7.1 Welding, Brazing, and Soldering
694
16.7.2 Adhesive Bonding 697
16.7.3 Diffusion Bonding 698
16.7.4 Mechanical Joining 699
16.8 Surface Coatings and Treatments 699
16.8.1 Application of Coatings and
Painting 700
16.8.2 Surface Treatments 701
Case Study: Material and Process Selection
for Automobile Engine
Crankshafts 702
16.9 Single-Crystal and Semiconductor
Processing 702
16.9.1 Growth and Processing of Single
Crystals 703
16.9.2 Oxidation 704
16.9.3 Lithography and Etching 704
Case Study: Mask Selection for Doping of Si
Wafers 705
16.9.4 Diffusion and Ion Implantation 705
16.9.5 Interconnection, Assembly, and
Packaging 707
16.10 Fiber Manufacturing 708
16.10.1 Melt Spinning 709
16.10.2 Solution Spinning 709
16.10.3 Controlled Pyrolysis 711
16.10.4 Vapor-Phase Processes 711
16.10.5 Sintering 712
16.10.6 Chemical Reaction 713
16.11 Composite-Manufacturing Processes 714
16.11.1 Polymer-Matrix Composites
(PMCs) 714
16.11.2 Metal-Matrix Composites
(MMCs) 715
16.11.3 Ceramic-Matrix Composites
(CMCs) 717
Summary 717
Key Terms 719
Homework Problems 719
17 MATERIALS AND ENGINEERING DESIGN 724
17.1 Introduction 726
17.2 Unified Life-Cycle Cost Engineering
(ULCE) 727
17.2.1 Design and Analysis Costs 727
17.2.2 Manufacturing Costs 728
17.2.3 Operating Costs 728
17.2.4 Cost of Disposal 728
Case Study: Cost Consideration in Materials
Selection 729
17.3 Material and Process Selection 730
17.3.1 Databases for Material
Selection 731
17.3.2 Materials and Process
Standards 732
17.3.3 Impact of Material Selection on the
Environment 733
Case Study: Material Selection for Electronic
Package Casing 736
Case Study: Material Selection for a Nuclear
Waste Container 739
Case Study: Development of Lead-Free,
Free-Cutting Copper Alloy 740
17.4 Risk Assessment and Product Liability 743
17.4.1 Failure Probability Estimation 744
17.4.2 Liability Assessment 746
17.4.3 Quality Assurance Criteria 746
Case Study: Inspection Criterion for Large
Industrial Fans 747
17.5 Failure Analysis and Prevention 748
17.5.1 General Practice in Failure
Analysis 749
Case Study: Failure Analysis of
Seam-Welded
Steam Pipes 752
Case Study: Failure in Wire Bonds in
Electronic Circuits 755
Case Study: Failure in a Polyethylene
Pipe 756
17.5.2 Failure Analysis in Composite
Materials 757
17.5.3 Failure Prevention 759
Case Study: Inspection Interval Estimation
for an Aerospace Pressure
Vessel 760
Case Study: Choosing Optimum Locations for
Probes during Ultrasonic
Testing 764
Summary 765
Homework Problems 765
APPENDICES
A Periodic Table of the Elements 769
B Physical and Chemical Data for the
Elements 770
C Atomic and Ionic Radii of the Elements 773
D Mechanical Properties 775
E Answers to Selected Problems 790
Glossary 793
References 806
Index 808
pg002 [V] G6 7-27060 / IRWIN / Schaffer rps 12-24-97 pgm/iq 1-9-98 mp
C H A P T E R 1
MATERIALS SCIENCE
AND ENGINEERING
1.1 Introduction
1.2 The Role of Materials in Technologically Advanced Societies
1.3 The Engineering Profession and Materials
1.4 Major Classes of Materials
1.5 Materials Properties and Materials Engineering
1.6 The Integrated Approach to Materials Engineering
1.7 Engineering Professionalism and Ethics
pg003 [R] G5 7-27060 / IRWIN / Schaffer bmb 3-26-98 MP2
MATERIALS IN ACTION Building Blocks of Technology
Materials are at the core of all technological advances. Mastering the development, synthesis, and processing
of materials opens opportunities that were scarcely dreamed of a few short decades ago. The truth of this
statement is evident when one considers the spectacular progress that has been made in such diverse fields
as energy, telecommunications, multimedia, computers, construction, and transportation. Travel by jet aircraft
would be impossible without the materials that were developed specifically for the jet engine, and there would
be no computers as we know them without solid-state microelectronic circuits. Indeed, it has been stated that
the transistor has had the most far-reaching impact of any scientific or technological discovery to date. The
centrality of materials to advanced technical societies was recognized in a recent report to the U.S. Congress
authored by some of the most distinguished educators and scientists in the country. In that report it was stated
that
advanced materials and advanced processing of materials are critical to the nation’s quality of life, security, and
economic strength. Advanced materials are the building blocks of advanced technologies. Everything Americans
use is composed of materials, from semiconductor chips to flexible concrete skyscrapers, from plastic bags to a
ballerina’s artificial hip, or the composite structures on spacecraft. The impact of materials extends beyond
products, in that tens of millions of manufacturing jobs depend on the availability of high-quality specialized
materials.
In that same report it was further stated that
advanced materials are the building blocks of technology. When processed in particular ways, they enable the
technological advances that constitute progress. Advanced materials and processing methods have become essen-
tial to the enhancement of [the] quality of life, security, industrial productivity and economic growth. They are the
tools for addressing urgent problems, such as pollution, declining natural resources and escalating costs.
The ability to develop and use materials is fundamental to the advancement of any society. In this text we
will explore how that is done by engineers to improve the well-being of mankind.
Source: Reprinted from Materials Science and Engineering for the 1990s: Maintaining Competitiveness in the Age of
Materials, National Research Council, Washington, D.C. (National Academy Press, 1989).
3
pg004 [V] G2 7-27060 / IRWIN / Schaffer rps 12-24-97 rps QC1
4 Chapter 1 Materials Science and Engineering
1.1 INTRODUCTION
Our purpose in this bookis to examine the way in which materials impact society and to
show how they are produced, processed, and used in all branches of engineering to ad-
vance the well-being of society. In doing this, we will emphasize the relationship between
the structure of a material and its underlying properties, and we will develop general
principles applicable to all materials. Our goal in following this approach is to enable
students to develop a fundamental understanding of material behavior that will help
prepare them for a rapidly changing, and sometimes bewildering, environment. Since
engineering is essentially an applied activity, practical examples that build on and amplify
the fundamentals will also be emphasized for all topics and materials that are considered.
The final chapter presents case studies in which the principles and practical information
developed in the preceding chapters are integrated into the solution of real, materials-
based engineering problems.
In the remainder of this chapter, we will review the fundamental relationship between
a society’s economic well-being and its ability to understand and convert materials into
usable forms. We will introduce the importance of the relationships between structure,
properties, and processing for all classes of (solid) materials in all branches of engineer-
ing. The chapter concludes with examples of some of the exciting opportunities and
challenges that lie ahead in the areas of mechanical, aerospace, electrical, and chemical
engineering.
1.2 THE ROLE OF MATERIALS IN TECHNOLOGICALLY ADVANCED SOCIETIES
Throughout history, most major breakthroughs in technology have been associated with
the development of new materials and processes. For example, consider the materials-
processing innovations that led to the development of the Damascus sword. Two methods
were used to fabricate such swords. In one process, alternating layers of soft iron and steel
(in this case Fe with about 0.6% C) were hammered together at high temperatures to
produce a blade that had an edge of hard steel to retain a sharp cutting surface and a body
of iron that provided resistance to fracture. In Japan, similar results were obtained by
hammering steel into a thin sheet and then folding it back upon itself many times. A
finished Japanese sword is shown in Figure 1.2–1; the variations in structure are quite
FIGURE 1.2–1 Photographs of the front and back sides of a Japanese sword forged by Hiromitsu in the mid-16th
century. The smoothly waving outline was produced by polishing and the contrast enhanced by lighting. The structure
of the hard and soft areas (mottled regions) can be seen along the edge from the tip to the midpoint. (Source: Cyril
Stanley Smith, A Search for Structure: Selected Essays on Science, Art, and History, MIT Press, Cambridge, MA, copy-
right 1992.)
1250°C
1100°C
1000°C
1100°C
1250°C
1400°C
1100°C
1250°C
1450°C
Lower surface area
Side view
430°C
650°C
1400°C
1100°C
1220°C
1150°C
400°C
pg005 [R] G1 7-27060 / IRWIN / Schaffer rps 12-25-97 plm 3-21-98 MP
Chapter 1 Materials Science and Engineering 5
clear. The result of either processing method was a novel layered metal structure. Weap-
ons produced from metals with this new structure gave their possessors a great advantage
in battle. Similarly fabricated weapons in the Middle East provided one basis for the
spread of the Syrian empire.
This example illustrates one of the key principles of materials science and engineer-
ing—the intimate link between structure, properties, and processing. The structure of the
metal resulting from innovative processing methods provided new combinations of prop-
erties that offered significant advantage to those who developed the technology. Thus,
these swords represent one of the first engineered materials.
More recently, development of processes to obtain precise compositional and struc-
tural control has made miniaturized transistor technology possible. The result has been an
electronics revolution that produced products such as computers, cellular phones, and
compact disk players that continue to affect all aspects of modern life.
Another area where materials provide the springboard for advance is the aerospace
industry. Light, strong alloys of aluminum and titanium have fostered the development
of more efficient airframes, while the discovery and improvement of nickel-base alloys
spurred development of powerful, efficient jet engines to propel these planes. Further
improvements are being made as composites and ceramics are substituted for conven-
tional materials.
The role of materials in the exploration of space is of central importance. One promi-
nent example lies with the U.S. space shuttle. During reentry, extremely high tempera-
tures develop as a result of friction between the earth’s atmosphere and the shuttle. These
temperatures, which can exceed 1600�C, would melt any metal currently used in air-
frames. Ceramic tiles, which have the ability to withstand extremely high temperatures
and have excellent insulating properties, provide a method for protecting the aluminum
frame of the spacecraft.
The approximate temperature distribution developed on the surface of the space shuttle
during reentry is shown in Figure 1.2–2. Those regions in which the temperature ranges
FIGURE 1.2–2
Surface temperatures of
U.S. space shuttle during
reentry into the earth’s at-
mosphere. (Source: G.
Lewis, Selection of Engi-
neering Materials, Prentice
Hall, Inc., Englewood Cliffs,
NJ, 1990.)
pg006 [V] G2 7-27060 / IRWIN / Schaffer rps 12-25-97 rps�plm 3-21-98 MP
6 Chapter 1 Materials Science and Engineering
between 400 and 1260�C have been protected with about 30,000 silica tiles. The tiles are
coated with a layer of black borosilicate glass to both insulate the surface and radiate
thermal energy from the shuttle. In those regions that may reach 1600�C, coated rein-
forced carbon/carbon composites (materials composed of carbon fibers surrounded by a
carbon matrix) are used. Without such materials, it is doubtful that a reusable space
vehicle would be possible. This is an example of the way our highest aspirations are real-
ized through our practical ability to develop and work with advanced materials.
Another example of materials providing the vehicle to technological breakthrough
occurs in telecommunications. Information that was once carried electrically through
copper wires is now being carried optically, through high-quality transparent SiO2 fibers
as shown in Figure 1.2–3. The optical properties of the fibers are deliberately and pre-
cisely varied across the fiber diameter to provide for maximum efficiency. Using this
technology has increased the speed and volume of information that can be carried by
orders of magnitude over what is possible using copper cable. Moreover, the reliability of
the transmitted information has been vastly improved. In addition to these benefits, the
negative effects of copper mining on the environment have been reduced, since the mate-
rials and processes used to produce glass fibers have more benign environmental effects.
The centrality of materials to the economic well-being of the United States has been
pointed out in the National Research Council study entitled Materials Science and
Engineering for the 1990s—Maintaining Competitiveness in the Age of Materials. This
document states that “materials science and engineering is crucial to the success of
industries that are important to the strength of the U.S. economy and U.S. defense.” A
similar position has been adopted by Japan, where the ability to develop, process, and
fabricate advanced materials has been declared the cornerstone of the nation’s strategy to
maintain a leading technological position.
1.3 THE ENGINEERING PROFESSION AND MATERIALS
In one way or another, materials are a major concern in all branches of engineering.In
fact, the definition of engineering according to the Accreditation Board for Engineering
and Technology makes this point clearly:
Engineering is the profession in which a knowledge of the mathematical and natural
sciences gained by study, experience, and practice is applied with judgment to develop
ways to utilize, economically, the materials and forces of nature for the benefit of
mankind.
FIGURE 1.2–3
Optical fiber preform used
to manufacture lightguides.
The rings represent areas
having different indices of
refraction. When the pre-
form is drawn, the final
fiber diameter is about
125 � 10�6 m.
(Source: Permission of
AT&T Archives.)
pg007 [R] G1 7-27060 / IRWIN / Schaffer rps 12-25-97 QC
Chapter 1 Materials Science and Engineering 7
If this definition is accepted, we can see that engineering is a profoundly human activity
that touches upon the life of all members of society. We can also see that an engineer is
not only an applied scientist but much more. The engineer must have a good business
sense, including an understanding of economics.
Important differences exist between the functions and approaches of engineers and
scientists. Engineering is essentially an integrating activity, while science is a reductionist
activity. The engineer often employs an intuitive, global (and, frequently, empirical)
approach as opposed to that of the scientist, who breaks a problem down into its most
basic elements to elucidate fundamental principles. In other words, an engineer is fre-
quently required to solve problems by synthesizing knowledge from various disciplines
and to produce items without a complete fundamental understanding of what he or she is
dealing with. In such cases an engineer must define the operating conditions and develop
a test program, based on his or her intuition, that will allow the project to move ahead in
a safe, orderly, and economical manner.
In carrying out a job, the engineer will be faced with an almost infinite number of
materials from which to choose. In some cases the materials will be put into service with
little or no modification required, while in other cases additional processing will be nec-
essary to obtain the desired properties. In choosing the best material for the job, the best
approach is to determine the properties that are required and to then see what material
will meet those properties at the lowest cost.
It is important to have a clear understanding of what is meant by the word cost. It does
not simply refer to the initial cost of an item. Something may have a high initial cost, yet
over the lifetime of the part, the total cost, taking all factors into account, may be low. An
approach that considers the lifetime of the component or assembly is commonly referred
to as life-cycle cost analysis. Factors such as reliability, replacement cost, the cost of
downtime, the cost of environmental cleanup or disposal, and many others must all be
considered. Materials play a key role in the life-cycle cost of a part. For example, consider
tennis rackets or skis fabricated from composites, or macroscopic mixtures, of carbon
fibers embedded in an epoxy matrix. While the initial cost of these items is relatively high,
they are very durable and over their (significantly longer) lifetime are much less expensive
than the metal or wood items they replaced.
It is also important for the engineer to realize that choice of materials cannot be made
on the basis of a single property. For example, if an electrical engineer is designing a
component in which the ability to conduct electricity is the principal property, he or she
must remember that the material must be capable of being economically fabricated into
the required form, be able to resist breaking, and have long-term stability so that the
properties will not change significantly with time. Thus, in the majority of cases, choice
of a material involves a complex set of trade-offs (including economic factors), and there
is seldom one single solution that is “right” for the given application. Alternatively stated,
there are often multiple “correct” solutions to a materials-selection problem; engineers
must investigate several alternate solutions before making a final selection.
In addition, as we have seen in the case of the space shuttle, the materials selected must
function together as a system. While each material is selected for specific properties to
fulfill a given need, the materials must also be capable of operating together without
degrading the properties of one another.
1.4 MAJOR CLASSES OF MATERIALS
The major classes of engineering materials are considered to be: (1) metals, (2) ceramics,
(3) polymers, (4) composites, and (5) semiconductors.Metalswithwhich you are probably
pg008 [V] G2 7-27060 / IRWIN / Schaffer rps 12-25-97 QC
8 Chapter 1 Materials Science and Engineering
familiar include iron, copper, aluminum, silver, and gold; common ceramics include sand,
bricks and mortar, (window) glass, and graphite; examples of familiar polymers are
cellulose, nylon, polyethylene, Teflon, Kevlar, and polystyrene; we have already discussed
mixtures of materials known as composites such as carbon/carbon composites used in
tiles on the space shuttle and carbon fibers in an epoxy matrix used in tennis rackets and
skis; and the simplest semiconductors are silicon and germanium. By understanding the
similarities and differences among these classes of materials, you will be in a position to
make intelligent materials choices that can meet the challenges of modern technology.
Why are materials arranged in the groups listed above? Many materials have similar
atomic structures or useful engineering properties or both that make it convenient to
classify them into these five broad groups. It should be recognized that these classifi-
cations are somewhat arbitrary and may change with new discoveries and advances in
technology. Composites, also sometimes called “engineered materials,” provide an excel-
lent example of a new classification. These materials are made by combining other (often
conventional) materials, using advanced technology, to obtain properties that could not be
obtained from the existing classes of materials.
In our discussion in this chapter and throughout the book we will emphasize that the
properties of a material are related to its structure. We will deal with structure at many
size scales ranging from the atomic scale (�0.1 � 10�9 m or 0.1 nm) through the
microscopic scale (�50 � 10�6 m or 50 �m), and up to the macroscopic scale (�10�2 m
or 1 cm). In the next chapter we will see that the material structure on each of these size
scales can be used to understand and explain certain materials properties.
While the properties of a material are related to its structure, it is important to
understand that the way in which a material is processed affects the structure and hence
the properties. As an example of this important concept, consider the dramatic effect that
thermal processing can have on the properties of steel. If slowly cooled from a high
temperature, steel will be relatively soft and have low strength. If the same steel is
quenched (i.e., rapidly cooled) from the same high temperature, it will be extremely hard
and brittle. Finally, if it is quenched and then reheated to some intermediate temperature,
it will have an excellent combination of strength and toughness. While we will study this
example in depth later in the text, the major point to be made here is that each of the three
thermal processes has produced a different structure in the same material, which in turn
gives rise to different properties.
Each of the five classes of materials, together with some elementary structure-property
relationships, is discussed briefly in the following sections.
1.4.1 Metals
Metals form solids in which the atoms are located in regularly defined, repeating positions
throughout thestructure. These regular repeating structures, known as crystals and dis-
cussed in detail in Chapter 3, give rise to specific properties. Metals are excellent conduc-
tors of electricity, are relatively strong, are dense, can be deformed into complex shapes,
and are resistant to breaking in a brittle manner when subjected to high-impact forces.
This set of mechanical and physical properties makes metals one of the most important
classes of materials for both electrical and structural applications. Extensive (and in some
cases exclusive) use of metals occurs in automobiles, airplanes, buildings, bridges, ma-
chine tools, ships, and many other applications where a combination of high strength and
resistance to brittle fracture is required. In fact, it is largely the excellent combination of
strength and toughness (i.e., resistance to fracture) that makes metals so attractive as
structural materials.
pg009 [R] G1 7-27060 / IRWIN / Schaffer rps 12-25-97 rps�plm 3-21-98 MP
Chapter 1 Materials Science and Engineering 9
The basic understanding of metals and their properties is advanced, and they are
considered to be mature materials with relatively little potential for major breakthroughs.
However, significant improvements have been and continue to be made as a result of
advances in processing. Two examples are:
� Higher operating temperatures in jet engines have been attained through the use
of turbine blades that are produced by controlled solidification processes. The
blades are made of alloys (atomic-scale mixtures of atoms) of nickel or other
metals and are in wide commercial use. Improvements will continue as proces-
ses are refined through use of advanced sensors and real-time computer control.
� Frequently parts are fabricated from metal powders by compacting them into a
desired shape at high temperature and pressure in a process known as powder
metallurgy (PM). An important reason for using PM processing is reduced fabri-
cation costs. While some improvement in properties can be obtained through
PM, a major benefit is the reduced variation in properties, which will allow the
operating loads to be safely increased. Reduced production costs through PM will
continue to impact the aerospace and automotive fields.
1.4.2 Ceramics
Ceramics are generally composed of both metallic and nonmetallic atomic species. Many
(but not all) ceramics are crystalline, and frequently the nonmetal is oxygen, as in Al2O3,
MgO, and CaO, all of which are typical ceramics. One significant difference between
ceramics and metals is that in ceramics, bonding is ionic and/or covalent. As a result there
are no “free” electrons in ceramics. They are generally poor conductors of electricity, but
are frequently used as insulators in electrical applications. One familiar example is spark
plugs, in which a ceramic insulator separates the metal components.
Ionic and covalent bonds are extremely strong. As a result, ceramic materials are
intrinsically stronger than metals. However, because of their more complex structure, the
ions or atoms cannot easily be displaced as a result of applied forces. Rather than bend
to accommodate such forces, ceramics tend to fracture in a brittle manner. This brittleness
generally limits their use as structural materials, although recent improvements have been
made by incorporating ceramic fibers into a ceramic matrix and other innovative tech-
niques. Ceramics’ rigid bond structure confers other advantages, including high tempera-
ture stability, resistance to chemical attack, and resistance to absorption of foreign
substances. They are thus ideal in high-temperature applications such as the space shuttle,
as containers for reactive chemicals, and as bowls and plates for foods where surface
contamination is undesirable.
Some ceramics are not crystalline. The most common example is window glass, which
is composed primarily of SiO2 with the addition of various metal oxides. Optical proper-
ties are of major importance in glass and may be controlled through composition and
processing. In addition the thermal and mechanical properties of glass can also be
controlled. Safety glass is simply glass that has been subjected to a thermal cycle that
leaves the surface in a state of compression and thereby resistant to cracking. In fact, glass
treated in this way is even difficult to crack when struck with a hammer!
Some current and potential applications for ceramic materials with a large economic
impact are listed below:
� In the automotive industry the thermal and strength properties of ceramics
make them very attractive for engine components. For example, there are over
60,000 autos in Japan with ceramic turbochargers, which increase the efficiency
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
pg010 [V] G2 7-27060 / IRWIN / Schaffer rps 12-25-97 rps QC1
10 Chapter 1 Materials Science and Engineering
of the automobile. The materials in this application are Si3N4 or SiC processed
to have some ability to resist brittle fracture.
� Ceramics based on compounds such as YBa2Cu3O7 and Ba2Sr2CaCu2Ox have
increased critical superconducting temperatures to � 95 K. This means that
superconducting films may be used as liners in microwave devices and as wires
for all kinds of applications. Improving the current-carrying capacity and con-
nection technology are essential for widespread application of these materials.
� Next-generation computers will have ceramic electro-optic components that
will give increased speed and efficiency.
1.4.3 Polymers
Polymers consist of long-chain molecules with repeating groups that are largely cova-
lently bonded. Common elements within the chain backbone include C, O, N, and Si. An
example of a common polymer with a simple structure, polyethylene, is shown in Fig-
ure 1.4–1. The bonds within the backbone are all covalent, so the molecular chains are
extremely strong. Chains are usually bonded to each other, however, by means of compar-
atively weak secondary bonds. This means that it is generally easy for the chains to slide
by one another when forces are applied and the strength is thus relatively low. In addition,
many polymers tend to soften at moderate temperatures, so they are not generally useful
for high-temperature applications.
Polymers, however, have properties that make them attractive in many applications.
Since they contain common elements and are relatively easy to synthesize, or exist in
nature, they can be inexpensive. They have a low density (in part because of the light
elements from which they are constituted) and are easily formed into complex shapes.
They have thus replaced metals for molded parts in automobiles and aircraft applications,
especially where the load-bearing requirements are modest. Because of these properties,
as well as their chemical inertness, they are used as beverage containers and as piping in
plumbing applications.
Like metals and ceramics, their properties can be modified by compositional changes
and by processing. For example, substitution of a benzene ring for one in four hydrogen
atoms converts polyethylene, shown in Figure 1.4–1, to polystyrene, Figure 1.4–2.
Polyethylene is pliable and is used for applications such as “squeeze bottles.” In poly-
styrene, the comparatively large benzene side group restricts the motion of the long-chain
molecules and makes the structure more rigid. If the benzene group in polystyrene is
replaced with a Cl atom (intermediate in size between H and the benzene ring), poly-
vinylchloride is produced. The Cl atom will restrict the chain mobility more than an
H atom but less than a benzene ring. A leathery material is produced with somewhat
intermediate properties between polyethylene and polystyrene. These three polymers
illustrate the fundamental principle, applicable to all materials, of the relationship be-
tween material structure andproperties.
FIGURE 1.4–1 Schematic of the structure of polyethylene. The mer or basic repeating unit in the polymer is the
@ C2H4@ group.
C
H
H
C
H
C
H
H
C
H
C
H
H
C
H
Fiber
Matrix
Fiber
pg011 [R] G1 7-27060 / IRWIN / Schaffer rps 12-25-97 rps QC1
Chapter 1 Materials Science and Engineering 11
Some current and potential applications for polymers include the following:
� The development of biodegradable polymers offers the potential for minimizing
the negative impact on our environment that results from the tremendous amount
of waste our society generates.
� Advances in liquid-crystal polymer technology may permit development of light-
weight structural materials.
� Electrically conducting polymers may be able to replace traditional metal wires
in weight-critical applications such as electrical cables in aerospace vehicles.
1.4.4 Composites
Composites are structures in which two (or more) materials are combined to produce a
new material whose properties would not be attainable by conventional means. Examples
include plywood, concrete, and steel-belted tires. The most prevalent applications for
fiber-reinforced composites are as structural materials where rigidity, strength, and low
density are important. Many tennis rackets, racing bicycles, and skis are now fabricated
from a carbon fiber–epoxy composite that is strong, light, and only moderately expensive.
In this composite, carbon fibers are embedded in a matrix of epoxy, as shown in Fig-
ure 1.4–3. The carbon fibers are strong and rigid but have limited ductility. Because of
their brittleness, it would not be practical to construct a tennis racket or ski from carbon
alone. The epoxy, which in itself is not very strong, plays two important roles. It acts as
a medium to transfer load to the fibers, and the fiber-matrix interface deflects and stops
small cracks, thus making the composite better able to resist cracks than either of its
constituent components.
FIGURE 1.4–2 Schematic of the structure of polystyrene. This polymer has the same basic structure as the
polyethylene shown in Figure 1.4–1 except that a benzene ring (C6H5) has been substituted for one of the four
H atoms. As a result of the larger side group, which hinders the sliding motion of adjacent polymer chains, polystyrene
is stiffer than polyethylene.
FIGURE 1.4–3
A cross-sectional view of a
carbon-epoxy composite
showing the strong and
stiff graphite fibers embed-
ded in the tough epoxy ma-
trix. (Source: Bhagwan D.
Agarwal and Lawrence J.
Broutman, Analysis and
Performance of Fiber Com-
posites, 2nd ed., copyright
� 1990 by John Wiley &
Sons, New York. Reprinted
by permission of John
Wiley & Sons, Inc.)
Gun loader door
Avionics access doors
Outer wing skin
Inner wing skin
Lex access cover
Trailing wing flap
Stabilizer access cover
Speed balance
Horizontal stabilizer
Vertical stabilizerStabilizer leading edge
Fixed trailing
 edges
Seals
Dorsal covers
pg012 [V] G2 7-27060 / IRWIN / Schaffer rps 12-25-97 rps�plm 3-21-98 MP
12 Chapter 1 Materials Science and Engineering
The strength and rigidity of a composite can be controlled by varying the amount of
carbon fiber incorporated into the epoxy. This ability to tailor properties, combined with
the inherent low density of the composite and its (relative) ease of fabrication, makes this
material an extremely attractive alternative for many applications. In addition to the
sporting goods described above, similar composites are used in aerospace applications
such as fan blades in jet engines (where the operating temperatures are low) and for
control surfaces in airframes. The use of composites in the F-18 fighter aircraft is shown
in Figure 1.4–4.
Composites can also be fabricated by incorporating strong ceramic fibers in a metal
matrix to produce a strong, rigid material. An example is SiC fibers embedded in an
aluminum matrix. Such a composite, known as a metal matrix composite, finds applica-
tion as an airframe material for components in which moderate loads are encountered,
such as in the skin of the fuselage.
Composites in which metal fibers are embedded in a ceramic matrix (ceramic-matrix
composites) are produced in an attempt to take advantage of the strength of the ceramic
while obtaining an increase in the toughness from the metal fibers that can deform and
deflect cracks. When a crack is deflected, more load is required to make it continue to
propagate, and the material is effectively tougher.
Some exciting new developments and possibilities for composites include the
following:
� There is great potential to reduce the weight and increase the payload of air-
planes. Initial uses are for lightly loaded parts such as vertical stabilizers and
control surfaces made from carbon fiber–epoxy, but metal-matrix composites
will play an increasingly important role.
� High-temperature ceramic-matrix composites will increase operating tempera-
tures of engines.
� A significant challenge in increasing the use of composites is to learn to design
with materials having totally different modes of failure than do conventional
materials.
FIGURE 1.4–4 Composites use in the F-18 fighter aircraft. (Source: Courtesy of McDonnell Douglas Corporation.)
pg013 [R] G1 7-27060 / IRWIN / Schaffer rps 12-25-97 rps�plm 3-21-98 MP
Chapter 1 Materials Science and Engineering 13
1.4.5 Semiconductors
The major semiconducting materials are the covalently bonded elements silicon and
germanium as well as a series of covalently bonded compounds including GaAs, CdTe,
and InP, among others. In some ways semiconductors are a subclass of ceramics, since
their bonding characteristics and mechanical properties are similar to those previously
described for ceramics. The commercial importance of semiconductors, however, war-
rants their consideration separately. For these materials to exhibit the level of reproduci-
bility of properties required by the microelectronics industry, semiconductors must be
processed in ways that permit precise control of composition and structure. In fact, the
processing techniques for semiconductors are among the most highly developed of
those used for any materials class. For example, impurity levels are routinely controlled
in the parts-per-billion range (i.e., a few impurity atoms for every billion host atoms).
The previous discussion on composites focused on materials used for structural appli-
cations. It should be understood that microelectronic devices are essentially composites
in which a host of radically different property requirements means that different classes
of materials (metallic conductors, active semiconducting elements, and ceramic insula-
tors) must be used in close proximity. One of the major challenges in the area of mi-
croelectronics lies in miniaturization and fabrication of these devices. The extremely fine
scale of present-day microelectronic devices is shown in Figure 1.4–5. Here it is clear that
many of the components of this composite structure are of submicron size!
Some present and future applications for semiconductors and microelectronic devices
are listed below:
� The dominant mode of information transfer is changing from electrical to opti-
cal signals. While the technology for optical communication has already been
developed, the materials and devices for optical computing are still in the
research stage. It is believed, however, that the developing technology will result
in much faster and therefore more powerful computational devices.
FIGURE 1.4–5 Microelectronic circuits. Note the very small size of some of the features on these devices.
(Source: Reprinted with permission from Materials Science and Engineering for the 1990s: Maintaining Competitiveness
in the Age of Materials. Copyright 1989 by the National Academy of Sciences. Courtesy of the National Academy