Introduction to Materials

Introduction

Material science is one of the oldest forms of engineering and applied science and is the study of the properties of materials. A branch of science & engineering that deals with

Material science refers to the branch of applied science which is concerned with investigating the relationship existing between the structures of materials and their properties and their interdisciplinary study of materials for practical purposes, their behaviour(state, phase,etc) at different chemical, physical and thermal conditions.

Materials science is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering.Modern material science evolved directly from metallurgy, which itself evolved from mining.material cycle

A material is any substance or mixture of substances that occupy a volume and has a mass.a material is that substance from which a product is modeled, cut and then fabricated. look around, it's everywhere since everything is made of a material

Types of materials

Broadly materials may be classified as following types

1. Metals

a. Good conductors of e^- and heat

b. Strong, deformable

c. Susceptible to chemical degradation in some atmospheres

d. High density

e. high strength, high stiffness, and have good ductility

f. magnetic property(diamagnetism or paramagnetism or ferromagnetism)

2 Polymers

a. Insulators of e^- and heat

b. Very flexible, deformable, low strength

c. Some transparent

d. Good corrosion resistance

e. Low resistance to heat

f. Low density

example bakelite, nylon, plastics, etc

3. Ceramics and Glasses

a. inorganic nonmetallic material

b. Insulators of e^- and heat

c. Hard, brittle, not deformable

d. Some transparent

e. Good corrosion resistance

f. Heat resistant

4. Composites

a.from two or more types of materials.

b. overall properties of the composites are superior to those of the individual components

Example- polymer/ceramic composites have a greater modulus than the polymer component, but aren't as brittle as ceramics.

5. Semi-conductors

a. a solid chemical element or compound that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current.

b. conductance varies depending on the current or voltage applied to a control electrode, or on the intensity of irradiation by infrared (IR), visible light, ultraviolet (UV), or X-ray.

2 types of semiconductors i.e.

1. intrinsic semiconductor
2. extrinsic semiconductor

Properties between conductor & insulator which can be modified by minor dopants.

Materials Properties

The properties of materials are depending on the following property

1.Physical Properties

They include properties determined by nature itself. they mainly include color, density, melting point, electrical conductivity, thermal expansion and magnetic properties.

2.Chemical Properties

Chemical properties are material characteristics that relate to the structure of a material and its formation from the elements. It mainly includes reactivity with environment, chemical inertness, stability of geometry of crystals,etc

3.Mechanical Properties

Mechanical properties are the characteristics of materials that are displayed when a force is applied to the material. These properties include hardness, modulus of elasticity, yield strength, tensile strength, percent elongation, reduction in area, impact, fatigue and creep strengths and wear resistance

4.Electrical properties

Electrical properties are the physical conditions that allow an electrical charge to move from atom to atom in a specific material. It includes the properties like conductivity, conductance, resistivity, resistance and their variance with temperature

5.Magnetic Properties

The material is whether magnetic or nonmagnetic is determined by this property, materials may be ferromagnets, paramagnets, diamagnetics if they show any magnetic behaviour

Relation between structure, processing and properties

Materials processing

Material processing is the series of operations that transforms industrial materials from a raw material state into finished parts or products. The processes used to convert raw materials into finished products perform one or both of two major functions: first, they form the material into the desired shape; second, they alter or improve the properties of the material. Some of the material processing methods are casting, rolling, extrusion, compaction etc.

Material structure

All solid substances are either amorphous solids or crystalline solids. The differences between crystalline and amorphous solids are given below:

Amorphous solids Crystalline solids

Cooling Curve

The cooling curve of different materials may be similar to some extent or different. This mainly depends on upon crystal structure and geometry of the material. For crystalline solids, a discontinuous thermal arrest can be seen as in figure between a-b. This is crystallization process. Cooling curve for amorphous solids is rather continuous and smooth.

Material selection for design

Material selection is a step in the process of designing any object (physical). In the context of product design, the main goal of material selection is to minimize cost while meeting product performance goals. Selection of any material for a work depends on many factors. several things ought to be considered first before selecting any material for use. some factors include

Performance requirements of materials

Some performance requirements are

1. Function: For what purpose material is being used primarily determines whether any material be used or not.
2. Appearance: Compact, nicely shaped, attractive color products jump ahead in the market.A material should have a good appearance.
3. Service Life: Larger is the service life, higher is the quality of material is required so that structure shall last long till its service ends.
4. Environment: The structure should be prevented from hazardous environment situation(like rain, snowfall, extreme sunlight) to ensure optimum performance.
5. Compatibility: When more than one type of material is used in a product or assembly, material work harmoniously with each other
6. Cost: The low cost of a product is also very much important today to withstand competitive market.

Engineering requirements of materials

The main engineering requirements are as follows:

1.Fabrication Requirements: Material should be able to get shaped (e.g. cast, rolled, forged) and joined (e.g. welded, brazed etc.) easily

2. Service Requirements: Selected materials must stand up to service demand

3.Economic Requirements: The engineering parts should be made with minimum overall cost

Steps for selection of materials

The steps generally followed during selection of materials for material design are

1.firstly what type of materials may be required for the work may be analysed.

2.comparision between suitability of different material analysed is made secondly.

3.the material with the best property is compared with others in different aspects(cost, service life, availability

4.the materials so selected by above process is now directly used for manufacturing purpose.

My point of view for importance of material science

To provide a basic understanding of the structure of metals and its relation to the mechanical properties and failure modes of metals and alloys. To introduce the concepts of heat treatment, phase transformations, and microstructures of metals and alloys.