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ME-221: Materials Science and Engineering

Required text:Materials Science and Engineering: An Introduction,

W.D. Callister, Jr., 6th edition, John Wiley and Sons, Inc. (2003)

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• Recommended Books:

• Introduction to Engineering Materials (2nd ed. ) by V.B. John

• Properties of engineering materials by R.A. Higgins

• Modern Manufacturing Process Engineering by: Benjamin, Draper, &

Wysk.

• Materials & Processes in Manufacturing, (7th Ed.) by: Degarmo,

Black & Kohser

• Manufacturing Process, (8th ed.) by: Amstead, Ostwald & Begeman

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Assignment 10%Due one week from announcement date at the beginning of class

Test 1 10%

Mid Exam 20%

Final Exam 40%

GRADING

Lab Work 20%

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SCHEDULE Week Subject Chapter(s)

1 Introduction, classification of materials, atomic structure and bonding

1,2

2 Crystal structures, density calculations, APF, directions and planes

2,3

3 Close-packed crystal structures. 3, 12.1, 12.2 4 Point defects, dislocations, grain boundaries, metallography 4 5 Mechanical properties

Test 1 6

6 Stress-strain behavior, hardness, plastic deformation and twinning

6, 7

7 Strengthening mechanisms, recovery, recrystallization, grain growth

7

8 Spring Break Fracture mechanics, fatigue, creep 8 9 Test 2. 5,9

10 Phase diagrams: Fe-C system, non-equilibrium phases 9 11 Phase transformations 10 12 Phase transformations, nucleation and growth 10 13 Heat treatment, hardenability, precipitation hardening, 10, 11 14 Applications and processing of metal alloys 11 15 Applications and processing of metal alloys 11 16 Revision

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HISTORICAL PERSPECTIVE

MATERIALS SCIENCE AND ENGINEERING

WHY STUDY MATERIALS SCIENCE AND ENGINEERING?

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What is Materials Science???

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• A branch of science & engineering that deals with the inter-play between

structure, properties and processing of materials

Properties

Structure Processing

“Materials Science” “Materials Engineering”

• Materials Science: investigates relationship between materials’ structure &

properties

• Materials Engineering: On the basis of materials science, designing and/or

engineering the materials’ structure to produce desired properties

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<0.2 nm1 nm = 4x10-8 in

0.2-10 nm 1-1000 mm

Optical Microscope

>1 mm

Naked Eye

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Properties

Structure Processing

• Electronic level (subatomic)

• Atomic (molecular level, chemical composition)

• Crystal (arrangement of atoms or ions wrt one another)

• Microstructure (can study with microscopes)

• Macrostructure (can see with naked eye)

“Materials Science” “Materials Engineering”

Electronic & atomic structure

Crystalstructure

MicroStructure(electron & opticalmicroscopes)

MacroStructure(magnifying glass or naked eye)

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MATERIALS

Materials can be defined as anything which satisfies the human needs

or

Materials are substances of which some thing is composed or made of.

Since civilization began, materials along with energy have been used by people to improve their standard of living. Materials are everywhere about us since products are made of materials. Some of the commonly encountered materials are wood (timber), concrete, bricks, steel. plastic, glass, rubber, aluminum, copper and paper etc. If we look around we can easily realise that there are many more kinds of materials. These new types of materials are being frequently developed as a result of constant research and development.

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ENGINEERING MATERIALS :

The term engineering materials is specifically used to refer materials to produce technical products. However there is no limiting line between the terms Materials and Engineering materials, thus they can be used interchangeably.

Engineers design most of the manufacture products and their processing systems for the production of these products. These products require materials & engineers should have the knowledge of engineering materials i.e. an engineer should be knowledgeable about the structure and properties of the materials so that he is able to select the most suitable ones for each application and he is able to develop best processing methods.

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Structure-Property-Processing-Performance Relationship:

Many engineering activities depend upon the selection

of engineering materials whose properties match the requirements of

the application. Primitive cultures were often limited to the naturally

occurring materials in their environment. As civilization developed, the

spectrum of engineering materials expanded. Materials could be

processed and their properties altered and possibly enhanced. The

alloying and heat treatment of metals can change the properties of a

material.

While earlier successes in altering materials were

largely the result of trial and error, we now recognize that the properties

and performance of a material are the direct result of its structure and

processing. If we want to change the properties, we will have to induce

changes in the material structure.

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• example of processing-structure-properties-performance principles with Figure 1.2, a

photograph showing three thin disk specimens placed over some printed matter. It is

obvious that the optical properties (i.e., the light transmittance) of each of the three

materials are different; the one on the left is trans-parent (i.e., virtually all of the reflected

light passes through it), whereas the disks in the center and on the right are, respectively,

translucent and opaque. All of these specimens are of the same material, aluminum oxide,

but the leftmost one is what we call a single crystal—that is, it is highly perfect—which

gives rise to its transparency. The center one is composed of numerous and very small

single crystals that are all connected; the boundaries between these small crystals scatter

a portion of the light reflected from the printed page, which makes this material optically

translucent. Finally, the specimen on the right is composed not only of many small,

interconnected crystals, but also of a large number of very small pores or void spaces.

These pores also effectively scatter the reflected light and render this material opaque.

Thus, the structures of these three specimens are different in terms of crystal boundaries

and pores, which affect the optical transmittance properties. Further-more, each material

was produced using a different processing technique. And, of course, if optical

transmittance is an important parameter relative to the ultimate in-service application, the

performance of each material will be different.

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ex: hardness vs structure of steel • Properties depend on structure

Data obtained from Figs. 10.21(a)and 10.23 with 4wt%C composition,and from Fig. 11.13 and associateddiscussion, Callister 6e.Micrographs adapted from (a) Fig.10.10; (b) Fig. 9.27;(c) Fig. 10.24;and (d) Fig. 10.12, Callister 6e.

ex: structure vs cooling rate of steel • Processing can change structure

Structure, Processing, & Properties

Cooling Rate (C/s)

100

200

300

400

500

600

0.01 0.1 1 10 100 1000

(a)

30m

(b)

30m

(d)

30m(c)

4m

Hard

ness

(B

HN

)

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T (°C)-200 -100 0

Cu + 3.32 at%Ni

Cu + 2.16 at%Ni

deformed Cu + 1.12 at%Ni

1

2

3

4

5

6

Resi

stiv

ity,

(1

0-8

Oh

m-m

)

0

Cu + 1.12 at%Ni

“Pure” Cu

• Electrical Resistivity of Copper:

• Adding “impurity” atoms to Cu increases resistivity.• Deforming Cu increases resistivity.

Adapted from Fig. 18.8, Callister 6e.(Fig. 18.8 adapted from: J.O. Linde,Ann Physik 5, 219 (1932); andC.A. Wert and R.M. Thomson,Physics of Solids, 2nd edition,McGraw-Hill Company, New York,1970.)

ELECTRICAL

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• Thermal Conductivity of Copper: --It decreases when you add zinc!

Composition (wt%Zinc)Therm

al C

onduct

ivit

y

(W/m

-K)

400

300

200

100

00 10 20 30 40

Adapted from Fig. 19.4, Callister 6e.(Fig. 19.4 is adapted from Metals Handbook: Properties and Selection: Nonferrous alloys and Pure Metals, Vol. 2, 9th ed., H. Baker, (Managing Editor), American Society for Metals, 1979, p. 315.)

THERMAL

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Classification of engineering materials

Most of the Engineering materials can be

classified into main five categories as under:

1. Metallic materials

2. Polymeric materials

3. Ceramic materials

4. Composite materials

5. Electronic materials

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1-Metallic materials:

These are inorganic substances which are composed of one or more metallic elements. These are further classified into ferrous, and non-ferrous materials. Examples of metallic elements are Iron, Copper, Aluminum. Non-metallic elements such as Carbon, Nitrogen and Oxygen may also be contained in the metallic materials. Metals have crystalline structure, good thermal and electrical conductivity, good strength and ductility.

Ferrous materials contain large percentage of iron such as steels and cast irons and Non-ferrous materials that do not contain iron or only relatively small amount of iron. Example of non-ferrous metals are Al, Cu, Zn, Ti, & Ni.

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2- Polymeric materials

The word polymer is actually taken from two Greek words, Poly = many and mer = repeating units or parts. Polymeric materials are usually long organic molecular chains i. e., compounds of C & H. So the polymeric materials are organic compounds having many repeated units, e.g., Teflon, Nylon 6,6, Polythene etc.

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3- Ceramic materials:

The word ceramics actually is taken from the Greek word “ Keramos “ = burnt stuff / Clay.

Ceramics are inorganic materials consist of metallic & non-metallic elements chemically bonded together unlike metallic materials. They may be crystalline, non-crystalline or mixtures, e.g., glass, Refractories.

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4- Composite materials:Composite materials are mixtures of two or more materials to produce properties that are not produced in a single material, e.g., Fiber glass, concrete, plywood etc. The useful properties which can be produced in such materials are strength, stiffness, hardness, temperature resistance, corrosion resistance, conductivity etc.

5- Electronic materials: Electronic materials are used in electronics, especially microelectronics, e.g., Silicon, Germanium & Gallium Arsenide etc.

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Metals

Ceramics &

GlassesPolymers

Insulators of e- and heat

Very flexible, deformable, low strength

Some transparent

Good corrosion resistance

Low resistance to heat

Low density

All plastics, Nylon, Rubber

Insulators of e- and heat

Hard, brittle, not deformable

Some transparent

Good corrosion resistance

Heat resistant

SiC, Si3N4, Al2O3

Good conductors of e- and heat

Strong, deformable

Not transparent

Susceptible to chemical degradation in some atmospheres

High density

Fe, Steel, Cu, Al, Brass

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Semi-ConductorsProperties between conductor & insulator which can

be modified by minor dopants. Si

Smart (Functional) MaterialsShape memory alloys (NiTi), piezoeffect (PZT)

Sensors-actuatorsAdvanced Materials

Elements of IC, magnetic storage, LCDs, fiber optics, thin films, nano scale…

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Reading Assignment: Chapter 2