Constrictions and Jogs in Extended Dislocations

Abstract

A constriction (defined as a point at which the two partial dislocations are recombined) must be formed before an extended dislocation can climb. The energy required is found to be about 6 eV, but may be reduced in the presence of an applied stress. Constrictions are more easily formed in Cottrell-Lomer locked dislocations than in free dislocations; the climb of a locked dislocation is considered. The different types of jogs which may be formed in an extended dislocation are discussed. In an appendix a new derivation of the expression for the line tension of a dislocation is given.