Welcome to MME131:

Introduction to Metallurgy

and Materials

January 2018 Term

01Introduction to the Course

A. K. M. B. RashidProfessor, Department of MME

BUET, Dhaka

Topics to Cover

Why study materials and metallurgical engineering?

Historical perspective about materials

The essence of MME

Structure-properties-processing relation: Case studies

MME131: Course objectives, Lecture format, Reference books

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Selecting right material for a

specific problem

❖ Designing processes and

producing materials reliably and

economically

Investigating and designing new

materials, and improving

traditional materials

Studying structure and composition of

materials, and measuring properties of all kind

Selecting, predicting and analysing

performance of materials in service

Investigating failure of material and process

Why Study MME?

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Historical Perspective

Materials closely connected our culture and drive our society

The development and advancement of societies are dependent

on the available materials and their use

Early civilizations designated by level of materials development

Use of natural materials at the initial stages

Develop techniques to produce materials with superior qualities

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The evolution of engineering materials with time

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Stone Age (Paleolithic, ~2.5 Million BC)

• Flint : cutting edge easily formed by chipping Imp

rove

ma

teria

l pro

pe

rties

Incre

ase d

esig

n fle

xib

ilityCopper Age (~8000 – 5000 BC)

• Pottery kilns, hot enough to melt copper from ore

Strength σy = 70 MPa

Bronze Age (~3500 BC – 1200 BC)

• “Alloying”: add tin to copper

Strength σy = 125 MPa

Iron Age (~1500 BC – 1900 AD)

• Reduction of iron ore at high temperature with charcoal

releasing metallic iron

Strength σy = 275 MPa

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Steel Age (1900 AD – 1960 AD)

• Add carbon to iron You have got high strength steel

Strength σy > 1500 MPa

Non-ferrous and Polymer Age (1970 AD – )

• Aluminium, titanium and nickel (super alloys) for aerospace applications

• Silicon for information technology

• Plastics and composites for food preservation, housing, aerospace and higher speeds

Exotic Materials Age (~1960 AD – )

• Nano materials and bio-materials

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Properties of engineered

materials are function of:

• Raw materials elemental control

• Processing history

Our role in engineering materials then is to

understand the application and specify the

appropriate material to do the job as a function of:

• Strength (yield and ultimate)

• Ductility, flexibility

• Weight/density

• Working environment

• Cost: Lifecycle expenses, Environmental impact*

Economic and environmental factors often are the

most important when making the final decision !

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“Engineered” structures are not black boxes.

They are made from raw materials which have a processed

internal structure.

This internal structure affects the properties of the material.

The Essence of MME

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Understanding of how materials behave like they do, and why they differ in

properties was only possible with the atomistic understanding of matter

allowed by quantum mechanics, which first explained atoms and then solids.

The combination of physics, chemistry, and the focus on the relationship

between the properties of a material and its microstructure is the domain

of Materials Science.

The development of this science allowed designing of materials

and provided a knowledge base for the engineering applications

(Materials Engineering).

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structure

• arrangement of

internal components

• subatomic

• atomic

• microscopic

• macroscopic (bulk)• material synthesis

• method of producing object

using material

processing

properties

• material characteristics

• response to external stimulus

• mechanical, electrical, thermal,

magnetic, optical, deteriorative

• behavior of material in a particular application

• often judged by measuring properties and then

comparing them with standard values required

for the particular application

performance

The materials tetrahedron

The Structure - Processing - Properties - Performance Relation

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The internal conditions of materials

Relates to how a material is put together.

It has many dimensions….

What are Structures?

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1. Electronic or Subatomic Structure

• Electronic structure of individual atoms

(electrons and nucleus) that defines interaction

among atoms (interatomic bonding)

2. Atomic Structure

• Arrangement of atoms or molecules in materials material with the same atom can have different properties

(e.g. two forms of carbon: graphite and diamond)

• When arranged in 3D space, these are called

crystal structures.

3. Microscopic Structure

• Groups of atoms that are agglomerated

together to form small grains gives different properties (e.g., strength,

optical properties etc.)

4. Macroscopic Structure

• Structural elements that may be viewed

with the naked eye

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Optical Microscope

Microstructure of steel (0.8% C)

Microstructure of brass (70Cu-30Zn)

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Scanning Electron Microscope (SEM)

Carbon nanotube

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Calcium Phosphate Crystals

Electron diffraction pattern

Transmission Electron

Microscope (SEM)

TEM micrograph of Al-Cu alloy showing CuAl2 precipitates

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X-Ray Diffractometer

Bragg’s law

X-ray pattern

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Macrostructure (or, shape) of the hammer

Ferrite

grains

Pearlite

grains

0.38 wt.% carbon steel hammer head microstructure

Grain

boundary

Example of structures: Steel hammer head

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Crystal structure of the hammer head

Iron has a body-centred cubic (BCC) crystal structure

at room temperature

26P30N

Electronic structure of iron that make the hammer

The 2 electrons in the outer

shell are not tightly held. This

allows iron to form metallic

bonds with long-range crystal

structure, and to conduct

electricity

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10-12

10-9

10-6

10-3

10-0

size, m

Atomic structure

Crystal structure

Microstructure

Macrostructure

X-ray & neutron

diffraction

Transmission electron

microscopy

Scanning electron

microscopy

Optical microscopy

Logarithmic scale of structures

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What are Properties?

Properties are the material

traits (distinguishing features)

indicating the ways the material

responds to the environment

and external forces.

Virtually all important properties of solid materials

may be grouped into six different categories:

• Mechanical properties – response to mechanical forces (elastic modulus, strength, ductility, etc.)

• Electrical properties – response electrical fields (conductivity, dielectric constant, etc.)

• Magnetic properties – response magnetic fields (magnetization, permeability, etc.)

• Thermal properties are related to transmission of heat (heat capacity, thermal conductivity, etc.)

• Optical properties relate to the absorption, transmission and

scattering of electromagnetic or light radiation (refraction index, reflectivity, etc.)

• Chemical stability indicates reactivity with the environment (corrosion resistance, etc.)

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What are Processing?

In addition to structure and

properties, two other important

components are involved in the

science and engineering of

materials — namely, processing

and performance.

• Composition means the chemical make-up of a

material.

• Synthesis is the process by which materials are

made from naturally occurring or other chemicals.

• Processing means different ways of shaping

materials into useful components or changing their

properties.

• Performance means the accomplishment relative to

stated goals or objectives.

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Application of materials tetrahedron to automotive steels chassis

C: Synthesis and Processing

•How can the steelmaking be

controlled so as to provide a high

level of toughness and formability?

•How can be the aerodynamic

car chassis be formed?

B: Microstructure

•What features of the structure

limit the strength and

formability?

•What controls the

strength?

•What is the strength-to-density ratio?

•What is the formability?

•How does this relate to the

crashworthiness of the vehicle?

•What is the cost of fabrication?

Performance

/ Cost

A: Compositions

• Iron-based?

•Aluminium-based?

•What alloying element should be used?

•What quantities?

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From structures to properties: Example

Structure-Property-Processing Relation

Polycrystalline with 5%

Porosity (Opaque)

Composed of many small,

interconnected crystals and a large

number of very small pores or void

spaces, which effectively scatter all

the reflected light and render this

material opaque.

Polycrystalline (Translucent)

Composed of numerous and very small single

crystals that are all connected (making a fully

dense material); the boundaries between these

small crystals scatter a portion of the light

reflected from the printed page, which makes

this material optically translucent.

Single Crystal (Transparent)

Composed of single crystal (a high

degree of perfection) — which gives

rise to its transparency.

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During rolling operation, the grains of material

are deformed and become elongated along the

rolling direction, which imparts directional, or

anisotropic properties to the material.

During casting, the liquid metal cools from

three directions and grains of uniform shape

are created, which imparts non-directional,

or isotropic properties to the material.

From processing to structure: Example

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From processing to property: Example

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MME131: CO & CLO

Course Objectives (CO)

1. To introduce the fundamental concepts of materials and metallurgical

engineering, as applied to engineering disciplines

2. To understand how the engineering properties of materials are

controlled by their structures

3. To learn how processing can be used to change the structure and,

therefore, properties and uses of engineering materials

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Course Learning Outcomes (CLO)

On successful completion of the module, you will be able to:

1. describe and account for the structure, processing routes

and key properties of the main classes of materials

2. explain how materials are characterised

3. construct structure-processing-property relationships for existing

and potential materials

4. assess the suitability of a material for a given purpose,

using quantitative analyses where appropriate

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MME131: Brief Lecture Format

1 – 3 Introduction

4 – 21 Properties and Application of Materials

22 – 25 Controlling Microstructure and Properties of Materials

26 – 36 Processing and Design of Materials

37 – 38 Materials Selection and Design

39 Nondestructive Testing of Materials

40 – 42 Review Classes

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Reference Books:

1. Callister. Materials Science and Engineering: An Introduction

2. Ashby and Jones. Engineering Materials 1 & 2

3. Shackelford. Introduction to Materials Science for Engineers

4. Askeland. The Science and Engineering of Materials

MME131: References

My website where I shall post all my lectures and other resources:

www.teacher.buet.ac.bd/bazlurrashid

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MME131: Grading

Continuous Assessment

Attendance : 10 %

Quiz (4), Assignments (2) : 20 %

3-hr Final Examination

Section A (Internal) 35 %

Section B (External) 70 %

Attendance less than 60 % of classes will result

a ZERO grade in attendance.

Two of the four quizzes/class tests will be unannounced!

Scheduled submission of assignments will improve the

grades of continuous assessment.

All quizzes and exam are closed book / closed notes.

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