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ENGINEERING MATERIALS &

PROPERTIES

(EPSE-300)Engr. Kashif Mushtaq

Lecturer

Engineering Systems & Solar EngineeringDepartment

kashif.mushtaq@nhu.edu.pk

EnggM

aterials-LectureNo.4

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Lecture No. 4

STRUCTURE OF METALS

mailto:Kashif.mushtaq@nhu.edu.pkmailto:Kashif.mushtaq@nhu.edu.pk

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COURSE MATERIAL

Textbook(s):

Material Science and Engineering by

William. D. Callister

Reference Book(s):

Materials and processes in Manufacturing

by E.P Degarmo, Process and Materials of Manufacturing by

Lindberg

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PREFACE

Crystal structure is one of the most important

aspects of materials science and engineering as

many properties of materials depend on their

crystal structures.

The basic principles of many materials

characterization techniques such as X-ray

diffraction (XRD), Transmission electron

microscopy (TEM) are based on crystallography.

Therefore, understanding the basics of crystalstructures is of paramount importance.

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ATOMICARRANGEMENT

Crystalline periodic arrangement of atoms:

definite repetitive pattern

Non-crystalline or Amorphous random

arrangement of atoms.

The periodicity of atoms in crystalline solids can be

described by a network of points in space called

lattice. 4

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SYMMETRY

Symmetry refers to certain pattern or arrangement.A body is symmetrical when it is reproduced bycertain operation.

The symmetry word (somewhat distorted) itself

shows 2-fold rotation symmetry (restored by 180orotation).

In the picture below the plane looks identical after a90orotation. The plane has 4 fold rotation symmetryas it repeats itself 4 times (shown by the red dot) ina full 360orotation.

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SYMMETRYOPERATIONS

Operations are given below

1. Translation

2. Rotation

3. Reflection

4. Inversion

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TRANSLATION

The first point is repeated at equal distances along

a line by a translation uT, where T is the translationvector and u is an integer.

Translation on a point with coordinates

xyzx+a y+b z+c

where, a, b and c are the unit vectors in x, y and zdirections respectively.

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