Evolution of interfacial dislocation network during low-stress high temperature creep of particle strengthened alloy system using discrete dislocation dynamics simulations

Abstract: We use three-dimensional discrete dislocation dynamics simulations (DDD) to study the evolution of interfacial dislocation network (IDN) in particle-strengthened alloy systems subjected to constant stress at high temperatures. We have modified the dislocation mobility laws to incorporate the recovery of the dislocation network by the climb. The microstructure consists of uniformly distributed cuboidal inclusions embedded in the simulation box. Based on the systematic simulations of IDN formation as a function of applied stress for prescribed inter-particle spacing and glide-to-climb mobility ratio, we derive a relation between effective stress and normalized dislocation density. We use link-length analysis to show self-similarity of immobile dislocation links irrespective of the level of applied stress. Moreover, we derive the dependence of effective stress on the ratio between mobile to immobile dislocation density based on the Taylor relation for strain hardening materials. We justify the relation with the help of a theoretical model which takes into account the balance of multiplication and annihilation rates of dislocation density.