6 February 2023

Difference between edge and screw dislocation

Edge dislocation differs from screw dislocation in that it happens when an extra half-plane of atoms exists in the middle of the crystal lattice, whereas screw dislocation occurs when the planes of atoms in the crystal lattice trace a helical course around the dislocation line. Let us check more differences between edge and screw dislocation here in this article. 

What is edge dislocation?

An instance of an edge dislocation is when the atoms on one side of the defect are moved in relation to the atoms on the other side. This could put the material under strain, which might result in a loss of strength or an increase in electrical conductivity. Edge dislocations can develop naturally as a crystal grows or they can be brought about by outside forces like stress or deformation.

What is screw dislocation?

A specific kind of linear flaw in the crystal lattice is called a screw dislocation. A plane of atoms is displaced in a spiral around a line in this line defect. It results from a disruption in the lattice structure caused by a shift in the crystal lattice. It is a particular kind of flaw that can lead to plastic deformation in a substance.

Edge dislocation Vs Screw dislocation

  • Edge dislocation happens when an additional row of atoms is added or removed. Due to the possibility of adding extra unit cells and atoms to the screw, screw dislocation facilitates simple crystal formation. 
  • The edge dislocation may have shear, tensile, and compressive stress fields. The screw dislocation lacks compressive, tensile, and shear stress fields.
  • Burger's vectors are always perpendicular to the dislocation line in edge dislocation. Burger's vectors are always parallel to the dislocation line in screw dislocation.
  • Inside a crystal, a region of lattice disturbance spreads along one edge in edge dislocation. The region of lattice disruption is divided into two planes that intersect at right angles in screw dislocation.
  • This dislocation develops as a result of the ascend and glide action. This dislocation develops due to glide action.
  • There are two types of edge dislocation one is positive and another is negative. Screw dislocation does not show any type of edge dislocation.
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