Models for long-/short-range interactions and cross slip in 3D dislocation simulation of BCC single crystals

Abstract

Models and rules for short-range interactions, cross slip and long-range interactions of dislocation segments for implementation in a 3D dislocation dynamics (3DD) model are developed. Dislocation curves of arbitrary shapes are discretized into sets of straight segments of mixed dislocations. Long-range interactions are evaluated explicitly based on results from the theory of dislocations. Models for short-range interactions, including, annihilation, formation of jogs, junctions, and dipoles, are developed on the basis of a `critical-force' criterion that captures the effect of the local fields from surrounding dislocations. In addition, a model for the cross-slip mechanism is developed and coupled with a Monte Carlo type analysis to simulate the development of double cross slip and composite slip. The model is then used to simulate stage I (easy glide) stress-strain behaviour in BCC single crystals, illustrating the feasibility of the 3DD model in predicting macroscopic properties such as flow stress and hardening, and their dependence on microscopic parameters such as dislocation mobility, dislocation structure, and pinning points.