Interaction between dislocations in the process of creep

Abstract

The forces of pairwise interaction between straight nonparallel dislocations in a bcc lattice have been calculated in the framework of the linear elasticity theory. The approximation chosen is fairly well applicable for the description of the initial stage of high-temperature creep. Concrete examples have been considered concerning the interaction between edge, screw, and mixed dislocations and their combinations as a result of which the mutual intersection with the formation of jogs on the dislocations may occur upon slip. It has been demonstrated with creep of single-crystal molybdenum that when low stresses are applied, mutual intersection of dislocations is unlikely and mixed and edge dislocations tend to accumulate in the form of subboundaries. In this case, neither screw dislocations are accumulated nor twist boundaries are formed. When external stresses are sufficient for dislocations to overcome the forces of mutual repulsion and attraction, mutual intersection of edge and mixed dislocations takes place with the formation of jogs on them in a concentration that is high enough to realize the creep mechanism controlled by climb of dislocations.