Transcript Foundations of Materials Science and Engineering Third Edition

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PowerPoint Lecture Slides
for
Foundations of Materials
Science
and
Engineering
Fourth Edition
William F. Smith
Javad Hashemi
CHAPTER
1
Introduction 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 constitute
78.08 and 20.95 percentage of dry
air by volume respectively.
1-2
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Why the Study of Materials is Important?
• Production and processing of materials constitute a
large part of our economy.
• Engineers choose materials to suite design.
• New materials might be needed for some new
applications.
 Example :- High temperature resistant materials.
 Space station and Mars Rovers should sustain
conditions in space.
* High speed, low temperature, strong but
light.
• Modification of properties might be needed for some
applications.
 Example :- Heat treatment to modify properties.
1-3
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Materials Science and Engineering
• Materials science deals with basic knowledge
about the internal structure, properties and
processing of materials.
• Materials engineering deals with the application
of knowledge gained by materials science to
convert materials to products.
1-4
Materials Science
Materials Science and
Engineering
Basic
Knowledge
of
Materials
Resultant
Knowledge
of Structure and
Properties
Materials Engineering
Applied
Knowledge
of 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
1-5
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 and
noncrystalline regions.
 Poor conductors of electricity and hence
used as insulators.
 Strength and ductility vary greatly.
 Low densities and decomposition
temperatures.
 Examples :- Poly vinyl Chloride (PVC),
Polyester.
 Applications :- Appliances, DVDs, Fabrics
etc.
1-6
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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.
1-7
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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 polyester
or epoxy matrix)
 Concrete ( Gravels or steel rods reinforced in
cement and sand)
 Applications:- Aircraft wings and engine, construction.
1-8
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Types of Materials
• Electronic Materials
 Not Major by volume but very
important.
 Silicon is a common electronic
material.
 Its electrical characteristics are
changed by adding impurities.
 Examples:- Silicon chips, transistors
 Applications :- Computers, Integrated
Circuits, Satellites etc.
1-9
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Competition Among Materials
• Materials compete with each
other to exist in new market
Example:1600
lb/Car
• Over a period of time usage
of different materials changes
depending on cost and
performance.
1400
1200
Aluminum
Iron
Plastic
Steel
1000
800
600
400
• New, cheaper or better
materials replace the old
materials when there is a
breakthrough in technology
200
0
1985
1992
1997
Model Year
Figure 1.14
Predictions and use of
materials in US automobiles.
1-10
After J.G. Simon, Adv. Mat. & Proc., 133:63(1988) and new data
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Future Trends
• Metallic Materials
 Production follows US economy closely.
 Alloys may be improved by better chemistry and
process control.
 New aerospace alloys being constantly
researched.
o Aim: To improve temperature and corrosion
resistance.
o Example: Nickel based high temperature super
alloys.
 New processing techniques are investigated.
o Aim: To improve product life and fatigue
properties.
o Example: Isothermal forging, Powder metallurgy.
 Metals for biomedical applications
1-11
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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 of engineering 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.
1-13
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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 FiberglassEpoxy and Graphite-Epoxy
combinations.
 Commercial aircrafts are expected to
use more and more composite materials.
1-14
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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 by
sensing 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 nm
 Examples: ceramics powder and grain size < 100
nm
 Nanomaterials are harder and stronger than bulk
materials.
 Have biocompatible characteristics ( as in
Zirconia)
 Transistors and diodes are developed on a
nanowire.
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Case Study – Material Selection
• Problem: Select suitable material for bicycle
frame and fork.
Steel and
alloys
Wood
Low cost but
Heavy. Less
Corrosion
resistance
Light and
strong. But
Cannot be
shaped
Carbon fiber
Aluminum
Reinforced
alloys
plastic
Ti and Mg
alloys
Very light and Light, moderately Slightly better
strong. No
Strong. Corrosion
Than Al
corrosion.
Resistance.
alloys. But much
Very expensive
expensive
expensive
Cost important? Select steel
Properties important? Select CFRP