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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display

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

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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.

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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.

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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

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