Defects in Crystals II: Dislocations

It was realised quite early that materials, particularly metals, can undergo permanent deformation (plastic deformation) at low stresses. A study of this intriguing phenomenon led to the discovery of dislocations. It was found that apart from providing an explanation for plastic deformation, dislocations play a role in various other aspects of crystal behaviour like crystal growth, hardness, fracture, thermal properties, etc. The subject of dislocations is thus of considerable importance.