1. Introduction To Materials Science and Engineering, Ch. 1
Chapter 1 Materials for Engineering
A fly-by during deployment of the aircraft carrier USS
Stennis. The pilot was grounded for 30 days, but he
likes the picture and thinks it was worth it.
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University of Tennessee, Dept. of Materials Science and Engineering

2. Introduction To Materials Science and Engineering, Ch. 1
Materials Science and
Engineering
• Materials Science – Investigating
relationships that exist between the structure
and properties of materials
• Materials Engineering – Is, on the basis of
these structure-property correlations,
designing or engineering the structure of a
material to produce a pre-determined set of
properties
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University of Tennessee, Dept. of Materials Science and Engineering

3. Introduction To Materials Science and Engineering, Ch. 1
Structure
• Sub atomic – electrons and nuclei (protons
and neutrons)
• Atomic – organization of atoms or
molecules
• Microscopic – groups of atoms that are
normally agglomerated together
• Macroscopic – viewable with the un-aided
eye
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University of Tennessee, Dept. of Materials Science and Engineering

4. Introduction To Materials Science and Engineering, Ch. 1
Terminology
mil = 1 / 1000 inch = 25.4 µm
micrometer = 1 / 1,000,000 meter = 1µm
Angstrom = 1 / 10,000,000,000 meter = 1Å
1 MICROMETER IS TWO WAVELENGTHS OF GREEN LIGHT LONG
A 1 MICRON WIDE LINE ON A CD
IS THE SAME SCALE AS A 100 FOOT
WIDE ROAD ON NORTH AMERICA
A HAIR IS 100 MICROMETERS
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University of Tennessee, Dept. of Materials Science and Engineering

5. Introduction To Materials Science and Engineering, Ch. 1
THE SCALE OF THINGS
The 21st century challenge -- Fashion materials at the nanoscale with desired properties and functionality
Things Natural 100 m 1 meter (m) Things Manmade
10-1 m 0.1 m
100 mm
Objects fashioned from
Progress in miniaturization
metals, ceramics, glasses, polymers ...
Monarch butterfly
~ 0.1 m 0.01 m
Dust mite 10-2 m
300 µm 1 cm
Head of a pin
10 mm 1-2 mm
Cat
~ 0.3 m
10-3 m 1 millimeter (mm)
Human hair Microelectronics
~ 50 µm wide 0.1 mm
Fly ash 10-4 m MEMS (MicroElectroMechanical Systems) Devices
Bee ~ 10-20 µm 100 µm 10 -100 µm wide
Microworld
Progress in atomic-level understanding
~ 15 mm
The
10-5 m 0.01 mm
10 µm
10-6 m 1 micrometer (µm)
spectrum
Visible
Red blood cells
with white cell Atoms of silicon
Magnetic ~ 2-5 µm Red blood cells
domains garnet spacing ~tenths of nm Pollen grain
film 10-7 m 0.1 µm
11 µm wide 100 nm
Nanoworld
stripes
Schematic, central core ATP synthase
The
10-8 m 0.01 µm
10 nm
Quantum dot array --
Indium arsenide germanium dots on silicon
quantum dot
10-9 m 1 nanometer (nm)
10
nm DNA
~2 nm wide
Cell membrane
-10
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University of Tennessee, Dept.10 m 0.1 nm
of Materials Science and Engineering

6. Introduction To Materials Science and Engineering, Ch. 1
Processing
Structure
Properties
Performance
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University of Tennessee, Dept. of Materials Science and Engineering

7. Introduction To Materials Science and Engineering, Ch. 1
Structure, Processing, & Properties
• Properties depend on structure
ex: hardness vs structure of steel
(d)
600
Hardness (BHN)
30µm
500 (c)
Data obtained from Figs. 10.21(a)
400 (b) and 10.23 with 4wt%C composition,
(a) and from Fig. 11.13 and associated
4µm discussion, Callister 6e.
300 Micrographs adapted from (a) Fig.
10.10; (b) Fig. 9.27;(c) Fig. 10.24;
30µm
and (d) Fig. 10.12, Callister 6e.
200 30µm
100
0.01 0.1 1 10 100 1000
Cooling Rate (C/s)
• Processing can change structure
ex: structure vs cooling rate of steel
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University of Tennessee, Dept. of Materials Science and Engineering

8. Introduction To Materials Science and Engineering, Ch. 1
The Materials Selection Process
1. Pick Application Determine required Properties
Properties: mechanical, electrical, thermal,
magnetic, optical, deteriorative.
2. Properties Identify candidate Material(s)
Material: structure, composition.
3. Material Identify required Processing
Processing: changes structure and overall shape
ex: casting, sintering, vapor deposition, doping
forming, joining, annealing.
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University of Tennessee, Dept. of Materials Science and Engineering

9. Introduction To Materials Science and Engineering, Ch. 1
Composition, Bonding, Crystal Structure
and Microstructure DEFINE Materials Properties
Composition
Bonding Crystal Structure
Thermomechanical
Processing
Microstructure
Electrical & Thermal
Mechanical Optical
Magnetic Properties
Properties Properties
Properties
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University of Tennessee, Dept. of Materials Science and Engineering

10. Introduction To Materials Science and Engineering, Ch. 1
ELECTRICAL
• Electrical Resistivity of Copper:
6
i Adapted from Fig. 18.8, Callister 6e.
a t%N (Fig. 18.8 adapted from: J.O. Linde,
5 3 .32 Ann Physik 5, 219 (1932); and
+
Resistivity, ρ
C.A. Wert and R.M. Thomson,
Cu %N
i
(10-8 Ohm-m)
Physics of Solids, 2nd edition,
at i
4
2 .16 a t% N McGraw-Hill Company, New York,
u+ .12
1970.)
C 1
3 C u+
ed
d eform a t%N
i
2 1.12
Cu+
u
1 r e” C
“Pu
0
-200 -100 0 T (°C)
• Adding “impurity” atoms to Cu increases resistivity.
• Deforming Cu increases resistivity.
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University of Tennessee, Dept. of Materials Science and Engineering

11. Introduction To Materials Science and Engineering, Ch. 1
MAGNETIC
• Magnetic Storage: • Magnetic Permeability
--Recording medium vs. Composition:
is magnetized by --Adding 3 atomic % Si
recording head. makes Fe a better
recording medium!
Magnetization
Fe+3%Si
Fe
Magnetic Field
Adapted from C.R. Barrett, W.D. Nix, and
Fig. 20.18, Callister 6e. A.S. Tetelman, The Principles of
(Fig. 20.18 is from J.U. Lemke, MRS Bulletin, Engineering Materials, Fig. 1-7(a), p. 9,
Vol. XV, No. 3, p. 31, 1990.) 1973. Electronically reproduced
by permission of Pearson Education, Inc.,
Upper Saddle River, New Jersey.
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University of Tennessee, Dept. of Materials Science and Engineering

12. Introduction To Materials Science and Engineering, Ch. 1
OPTICAL
• Transmittance:
--Aluminum oxide may be transparent, translucent, or
opaque depending on the material structure.
polycrystal: polycrystal:
single crystal low porosity high porosity
Adapted from Fig. 1.2,
Callister 6e.
(Specimen preparation,
P.A. Lessing; photo by J.
Telford.)
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University of Tennessee, Dept. of Materials Science and Engineering

13. Introduction To Materials Science and Engineering, Ch. 1
DETERIORATIVE
• Stress & Saltwater... • Heat treatment: slows
--causes cracks! crack speed in salt water!
crack speed (m/s)
10 -8 “as-is”
“held at
160C for 1hr
before testing”
10 -10 Alloy 7178 tested in
saturated aqueous NaCl
solution at 23C
increasing load
Adapted from Fig. 11.20(b), R.W. Hertzberg, "Deformation and
Fracture Mechanics of Engineering Materials" (4th ed.), p. 505,
Adapted from Fig. 17.0, Callister 6e. John Wiley and Sons, 1996. (Original source: Markus O.
(Fig. 17.0 is from Marine Corrosion, Causes, Speidel, Brown Boveri Co.)
and Prevention, John Wiley and Sons, Inc.,
4µm
1975.)
--material:
7150-T651 Al "alloy"
(Zn,Cu,Mg,Zr)
Adapted from Fig. 11.24,
Callister 6e. (Fig. 11.24 provided courtesy of G.H.
Narayanan and A.G. Miller, Boeing Commercial
Airplane Company.) 13
University of Tennessee, Dept. of Materials Science and Engineering

14. Introduction To Materials Science and Engineering, Ch. 1
Types of Materials
Metals: strong, ductile, tough, high density, conductors.
Ceramics: strong, brittle, low density, insulators.
Polymers: weak, ductile, low density, insulators.
Semiconductors: weak, brittle, low density, semi-conductors.
Composites: strong, ductile, low density, conductors, insulators.
Crystals: atoms have long range periodic order (a).
Glasses: atoms have short range order only (b).
(a) (b)
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University of Tennessee, Dept. of Materials Science and Engineering

15. Introduction To Materials Science and Engineering, Ch. 1
Types of Materials
Let us classify materials according to the way the atoms are bound together
(Chapter 2).
Metals: valence electrons are detached from atoms, and spread in an 'electron
sea' that "glues" the ions together. Strong, ductile, conduct electricity and heat
well, are shiny if polished.
Semiconductors: the bonding is covalent (electrons are shared between
atoms). Their electrical properties depend strongly on minute proportions of
contaminants. Examples: Si, Ge, GaAs.
Ceramics: atoms behave like either positive or negative ions, and are bound
by Coulomb forces. They are usually combinations of metals or
semiconductors with oxygen, nitrogen or carbon (oxides, nitrides, and
carbides). Hard, brittle, insulators. Examples: glass, porcelain.
Polymers: are bound by covalent forces and also by weak van der Waals
forces, and usually based on C and H. They decompose at moderate
temperatures (100 – 400 C), and are lightweight. Examples: plastics rubber. 15
University of Tennessee, Dept. of Materials Science and Engineering

16. Introduction To Materials Science and Engineering, Ch. 1
Metals
Several uses of steel and pressed aluminum.
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University of Tennessee, Dept. of Materials Science and Engineering

17. Introduction To Materials Science and Engineering, Ch. 1
Ceramics
Examples of ceramic materials ranging from household and lab
products to high performance combustion engines which utilize both
Metals and ceramics. 17
University of Tennessee, Dept. of Materials Science and Engineering

18. Introduction To Materials Science and Engineering, Ch. 1
Ceramics
Crystalline ceramics (a) and non-crystalline glasses (b) yield
inherently different properties for applications. Open circles
represent nonmetallic atoms, solids represent metal atoms.
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University of Tennessee, Dept. of Materials Science and Engineering

19. Introduction To Materials Science and Engineering, Ch. 1
Ceramics
Examples of glasses. Depending on the material structure, the glass
can be opaque, transparent, or translucent. Glasses can also be
Processed to yield high thermal shock resistance. 19
University of Tennessee, Dept. of Materials Science and Engineering

20. Introduction To Materials Science and Engineering, Ch. 1
Polymers
Polymers or commercially called “Plastics” need no intro.
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University of Tennessee, Dept. of Materials Science and Engineering

21. Introduction To Materials Science and Engineering, Ch. 1
Polymers
Polymer composite materials, reinforcing glass fibers in a
polymer matrix.
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University of Tennessee, Dept. of Materials Science and Engineering

22. Introduction To Materials Science and Engineering, Ch. 1
Semiconductors
(a)
(b)
(a) Micro-Electrical-Mechanical Systems (MEMS), (b) Si wafer
for computer chip devices.
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University of Tennessee, Dept. of Materials Science and Engineering

23. Introduction To Materials Science and Engineering, Ch. 1
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University of Tennessee, Dept. of Materials Science and Engineering

24. Introduction To Materials Science and Engineering, Ch. 1
Course Goals: SUMMARY
• Use the right material for the job.
• Understand the relation between properties,
structure, and processing.
• Recognize new design opportunities offered
by materials selection.
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University of Tennessee, Dept. of Materials Science and Engineering