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Foundations of MaterialsScience
andEngineering
Fourth Edition
William F. Smith
Javad Hashemi
PowerPoint Lecture Slides
for
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CHAPTER
1Introduction to
Materials Science
and
Engineering
1-1
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The Mars Rovers - Spirit and Opportunity
Spirit and Opportunity are made up of materials such as
* Metals * Ceramics * Composites * Polymers * Semiconductors
www.nasa.gov
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What are Materials?
Materials may be defined as substance of
which something is composed or made.
We obtain materials from earth crust and
atmosphere.
Examples :- Silicon and Iron constitute 27.72
and 5.00 percentage of weight of
earths crust respectively.
Nitrogen and Oxygen constitute78.08 and 20.95 percentage of dry
air by volume respectively.
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Why the Study of Materials is Important?
Production and processing of materials constitute alarge part of our economy.
Engineers choose materials to suite design.
New materials might be needed for some newapplications.
Example:- High temperature resistant materials.
Space station and Mars Rovers should sustainconditions in space.
* High speed, low temperature, strong butlight.
Modification of properties might be needed for someapplications.
Example :- Heat treatment to modify properties.
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Materials Science and Engineering
Materials science deals with basic knowledge
about the internal structure, properties andprocessing of materials.
Materials engineering deals with the application
of knowledge gained by materials science to
convert materials to products.
Resultant
Knowledgeof Structure and
Properties
Applied
Knowledgeof Materials
Materials ScienceMaterials Science and
Engineering Materials Engineering
Basic
Knowledgeof
Materials
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Types of Materials
Metallic Materials
Composed of one or more metallic elements.
Example:- Iron, Copper, Aluminum.
Metallic element may combine with
nonmetallic elements.
Example:- Silicon Carbide, Iron Oxide.
Inorganic and have crystalline structure.
Good thermal and electric conductors.
Metals and Alloys
Ferrous
Eg: Steel,
Cast Iron
Nonferrous
Eg:Copper
Aluminum
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Types of Materials
Polymeric (Plastic) Materials Organic giant molecules and mostly
noncrystalline.
Some are mixtures of crystalline andnoncrystalline regions.
Poor conductors of electricity and hence
used as insulators. Strength and ductility vary greatly.
Low densities and decompositiontemperatures.
Examples :- Poly vinyl Chloride (PVC),Polyester.
Applications:- Appliances, DVDs, Fabricsetc.
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Types of Materials
Ceramic Materials Metallic and nonmetallic elements are chemically
bonded together.
Inorganic but can be either crystalline, noncrystalline
or mixture of both.
High hardness, strength and wear resistance.
Very good insulator. Hence used for furnace lining for
heat treating and melting metals.
Also used in space shuttle to insulate it during exit and
reentry into atmosphere.
Other applications : Abrasives, construction materials,utensils etc.
Example:- Porcelain, Glass, Silicon nitride.
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Types of Materials
Composite Materials Mixture of two or more materials.
Consists of a filler material and a binding material.
Materials only bond, will not dissolve in each other.
Mainly two types :-
o Fibrous: Fibers in a matrix
o Particulate: Particles in a matrix
o Matrix can be metals, ceramic or polymer
Examples :-
Fiber Glass ( Reinforcing material in a polyesteror epoxy matrix)
Concrete ( Gravels or steel rods reinforced incement and sand)
Applications:- Aircraft wings and engine, construction.
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Types of Materials
Electronic Materials
Not Major by volume but veryimportant.
Silicon is a common electronic
material.
Its electrical characteristics arechanged by adding impurities.
Examples:- Silicon chips, transistorsApplications :- Computers, Integrated
Circuits, Satellites etc.
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C i h Th M G Hill C i I P i i i d f d i di l
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Competition Among Materials
Materials compete with each
other to exist in new market
Over a period of time usage
of different materials changes
depending on cost andperformance.
New, cheaper or better
materials replace the oldmaterials when there is a
breakthrough in technology
Example:-
0
200
400
600
800
1000
1200
1400
1600
lb/C
ar
1985 1992 1997
Model Year
Aluminum
Iron
Plastic
Steel
Predictions and use of
materials in US automobiles.
Figure 1.14
After J.G. Simon, Adv. Mat. & Proc., 133:63(1988) and new data1-10
C i ht Th M G Hill C i I P i i i d f d ti di l
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Future Trends
Metallic Materials
Production follows US economy closely.
Alloys may be improved by better chemistry andprocess control.
New aerospace alloys being constantly
researched.o Aim: To improve temperature and corrosion
resistance.
o Example: Nickel based high temperature superalloys.
New processing techniques are investigated.o Aim: To improve product life and fatigue
properties.
o Example: Isothermal forging, Powder metallurgy.
Metals for biomedical applications
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Future Trends
Polymeric (Plastic Materials)
Fastest growing basic material (9%
per year).
After 1995 growth rate decreased
due to saturation.
Different polymeric materials can
be blend together to produce new
plastic alloys.
Search for new plastic continues.
1-12
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Future Trends
Ceramic Materials
New family ofengineering ceramics are produced
last decade
New materials and applications are constantly
found.
Now used in Auto and Biomedical applications.
Processing of ceramics is expensive.
Easily damaged as they are highly brittle.
Better processing techniques and high-impact
ceramics are to be found.
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Future Trends
Composite Materials
Fiber reinforced plastics are primary
products.
On an average 3% annual growth from
1981 to 1987.
Annual growth rate of 5% is predicted
for new composites such as Fiberglass-
Epoxy and Graphite-Epoxy
combinations.
Commercial aircrafts are expected to
use more and more composite materials.
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Future Trends
Electronic Materials
Use of electronic materials such as silicon
increased rapidly from 1970.
Electronic materials are expected to play
vital role in Factories of Future.
Use of computers and robots will increase
resulting in extensive growth in use of
electronic materials.
Aluminum for interconnections in
integrated circuits might be replaced by
copper resulting in better conductivity.
1-15
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Future Trends
Smart Materials :Change their properties bysensing external stimulus.
Shape memory alloys: Strained material reverts
back to its original shape above a critical
temperature.
Used in heart valves and to expand arteries.
Piezoelectric materials: Produce electric field when
exposed to force and vice versa.
Used in actuators and vibration reducers.
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MEMS and Nanomaterials
MEMS: Microelectromechanical systems.
Miniature devices
Micro-pumps, sensors
Nanomaterials:Characteristic length < 100 nmExamples: ceramics powder and grain size < 100
nm
Nanomaterials are harder and stronger than bulkmaterials.
Have biocompatible characteristics ( as inZirconia)
Transistors and diodes are developed on ananowire.
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Case Study Material Selection
Problem: Select suitable material for bicycle
frame and fork.
Steel and
alloysWood
Carbon fiber
Reinforced
plastic
Aluminum
alloys
Ti and Mg
alloys
Low cost but
Heavy. Less
Corrosionresistance
Light and
strong. But
Cannot beshaped
Very light and
strong. No
corrosion.Very expensive
Light, moderately
Strong. Corrosion
Resistance.expensive
Slightly better
Than Al
alloys. But muchexpensive
Cost important? Select steel
Properties important? Select CFRP
Recommended