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Palestine Polytechnic UniversityDepartment of Mechanical Engineering

ME251: Materials Science

Course Objective:Introduce fundamental concepts in Materials Science

Syllabus Link: http://cet.ppu.edu/depts/me/metemplate/syllabus/maher_s/Material%20Sc%20SYLLABUS.htm

You will learn about:• material structure

• how structure dictates properties

• how processing can change structure

This course will help you to:• use materials properly – material selection

• realize new design opportunities with materials

Lecturer: Dr. Maher Al-Jabari

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Concept of Material Science and Engineering

Processing

Structure Properties

level Types

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COURSE OUTLINE AND CALENDERTOPICS WEEKS/HOURS

Introduction to Materials Science (Chapter 1) 1st / 2+

Atomic Structure & Interatomic Bonding (Chapter 2) 2nd / 2+

The Structure of Crystalline Solids (Chapter. 3) 3rd -5th / 8

Short Exam 1 5th / 1

Imperfections in Crystals (Chapter 4) 6th -7th / 4

Diffusion (Chapter 5) -7th / 2

Mechanical Properties of Metals (Chapter 6) 8th -9th / 6

Phase Diagrams (Chapter 9) 10th -12th /9

Midterm Exam 13th/1

Phase Transformation in Metals (Chapter 10) 13th /2

Heat treatment of metals (Chapter 11) 14th/3

Short Exam 2 15th/1

Introduction to other materials (Polymers and Ceramics - as time permit)

15th- rest

Final Exam University Schedule

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COURSE POLICIES

GRADING SYSTEM

Short Exam-1 10 %

Midterm Exam 30 %

Short Exam-2 10 %

Quizzes and Attendance 10 %

Final Exam 40 %

Students are required to attend all classes

Unexcused absence of exams is not accepted

Make-up exams are expected to be harder.

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Chapter 1 - Introduction

• What is materials science / engineering ? • Why should we know about it?

• Materials drive our society ??????? • History

– Stone Age– Bronze Age– Iron Age– Now?

• Silicon Age?• Polymer Age?

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Introduction

Structure / Levels: Subatomic (e.g. electron, protons) Atomic (atoms and molecules)Microscopic (grains: large groups)macroscopic (by eye)

Property: Response to a specified imposed stimulus Kind and magnitude

Processing: Example Heat Treatment

Applications: ?

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Example – Biomedical - Hip Implant

• Requirements– mechanical strength

(many cycles)– good lubricity– biocompatibility

Femoral Stem

Ball

AcetabularCup and Liner

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Other Applications

• Industry • Metal manufacturing • Dentists ?• Think of Others• In Hebron ?• In History ?• In Future ?

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Developments of New Types of Polymers

• Commodity plastics Ex. Polyethylene

PolypropylenePolystyreneetc.

•  Engineering Resins Ex. Polycarbonate

NylonPolysulfoneetc.

 Can polypropylene be “upgraded” to properties (and price) near those of engineering resins?

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

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

Structure, Processing, & Properties

Har

dnes

s (B

HN

)

Cooling Rate (ºC/s)

100

200

300

400

500

600

0.01 0.1 1 10 100 1000

(d)

30 m(c)

4 m

(b)

30 m

(a)

30 m

Just Keep in Mind to the end !

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Types of Materials• Metals: Metallic bonding

– Strong, ductile– high thermal & electrical conductivity– opaque, reflective.

• Polymers/plastics: Covalent bonding sharing of e’s– Soft, ductile, low strength, low density– thermal & electrical insulators– Optically translucent or transparent.

• Ceramics: Ionic bonding (refractory) – compounds of metallic & non-metallic elements (oxides, carbides, nitrides, sulfides)– Brittle, glassy, elastic– non-conducting (insulators)

• Others:• Composite Materials ?• Semi-conductors ?

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1. Pick Application Determine required Properties

2. Properties Identify candidate Material(s)

3. Material Identify required Processing

Processing: changes structure and overall shapeex: casting, vapor deposition, forming, joining, quenching, annealing.

Properties: mechanical, electrical, thermal,magnetic, optical, deteriorative.

Material: structure, composition.

The Materials Selection Process

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Properties

• THERMAL• ELECTRICAL• MAGNETIC• OPTICAL

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THERMAL

• Space Shuttle Tiles: - Silica fiber insulation offers low heat conduction.

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

Composition (wt% Zinc)

The

rmal

Con

duct

ivity

(W

/m-K

)

400

300

200

100

00 10 20 30 40

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ELECTRICAL• Electrical Resistivity of Copper:

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

Adapted from Fig. 18.8, Callister 7e.(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.)

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

Res

istiv

ity,

(10-8

Oh

m-m

)

0

Cu + 1.12 at%Ni

“Pure” Cu

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MAGNETIC• Magnetic Permeability vs. Composition: --Adding 3 atomic % Si makes Fe a better recording medium!

• Magnetic Storage: --Recording medium is magnetized by recording head.

Magnetic FieldM

ag

net

iza

tion Fe+ 3% Si

Fe

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• Transmittance: --Aluminum oxide may be transparent, translucent, or opaque depending on the material structure.

single crystalpolycrystal:low porosity

polycrystal:high porosity

OPTICAL

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• Strength • Fabricability • Corrosion Resistance• Availability • Cost • Appearance

Factors

Material Selection

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• Use the right material for the job.• Understand the relation between properties, structure, and processing.

• Recognize new design opportunities offered by materials selection.

• Do not forget the triangle:

Course Goals:

SUMMARY

Processing

Structure Properties