Material Science - Introduction

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Syllabus (GATE ME)

• Structure and Properties of Engineering Materials

• Phase Diagrams

• Heat Treatment of Materials

• Stress Strain Diagram

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Structure & Properties of Materials

Property of material depends on its structure and processing

Structure - How the atoms/molecules are arranged

Property - Performance in an engineering application in given condition

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Properties are categories as:

• Mechanical Properties

• Electrical Properties

• Thermal Properties

• Optical Properties etc.

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Why Material Properties are important

To select a suitable material for a given application.

Suppose we want to design a cryogenic engine. Requirement of material for this application are:

•Light Weight

•Compatibility with Fuel and Oxidizer

•Strength and Ductility at Cryogenic Temperature

Hence to choose a suitable material for this engine property data is critical.

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Material Categories

Metals - Characterized by free electrons. Good thermal and electrical conductivity. Example: Al, Steel, Titanium etc.

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Ceramics - Compound between metallic and non-metallic elements mostly oxides, carbides and nitrides. Typically insulator to heat and electricity. Hard but very brittle and maintains strength at high temperature.

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Polymers - Long chain organic compounds such as plastics and rubber. Low density and extremely flexible

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Composite - Composite is a combination of two material types and exhibits best characteristics from both of its constituent materials. Example - Fiberglass