Chapter 3 - Movement of Dislocations

Abstract

This chapter discusses the movement of dislocations in crystals. There are two basic types of dislocation movement. Glide or conservative motion occurs when the dislocation moves in the surface that contains both its line and the Burgers vector: a dislocation able to move in this way is glissile, one that cannot is called sessile. Climb or nonconservative motion occurs when the dislocation moves out of the glide surface, and thus normal to the Burgers vector. Glide of many dislocations results in slip, which is the most common manifestation of plastic deformation in crystalline solids. It can be envisaged as sliding or successive displacement of one plane of atoms over another on so-called slip planes. Discrete blocks of crystal between two slip planes remain undistorted. Further deformation occurs either by more movement on existing slip planes or by the formation of new slip planes.