Engineering Materials and Metallurgy: Unit 0: Review of Crystal Physics

Line Defects (or Dislocations)

Definition, Causes, Types | Crystal Defects or Imperfections

The defects, which take place due to dislocation or distortion of atoms along a line, in some direction, are called as line defects.

LINE DEFECTS (OR DISLOCATIONS)


1. What are Line Defects?

The defects, which take place due to dislocation or distortion of atoms along a line, in some direction, are called as line defects.

Line defects are also called dislocations. In the geometric sense, they may be called as one dimensional defects.

2. Causes of Dislocations

Dislocations are caused due to the following reasons:

(i) Growth accidents,

(ii) Internal thermal stress,

(iii) External stresses causing plastic flow,

(iv) Phase transformations,

(v) Segregation of atoms causing mismatches, etc.

3. Types of Dislocations

The two basic types of dislocations are:

(a) Edge dislocation, and

(b) Screw dislocation.

These dislocations are responsible for the useful property of ductility in metals, ceramics and polymers.

Engineering Materials and Metallurgy: Unit 0: Review of Crystal Physics : Tag: : Definition, Causes, Types | Crystal Defects or Imperfections - Line Defects (or Dislocations)