Role of equilibrium and non-equilibrium grain boundary stress fields on dislocation transmission

Abstract

This study presents an approach to investigate the influence of intergranular stresses induced by equilibrium and non-equilibrium grain boundaries (GBs) on dislocation transmission via the discrete dislocation dynamics simulation method. First, a disclination-based construct is used to describe the equilibrium intergranular stress fields of two symmetric tilt GBs. Then, slip transfer through these GBs is simulated via an algorithm that predicts dislocation transmission considering geometric and plastic dissipation criteria. Results show that the locations for transmission and the glide of residual dislocations are strongly correlated with GB stresses. Next, ordered structural defects in the equilibrium GBs are modified using a new approach to simulate disruptions in GB structure caused by dislocation transmission, creating non-equilibrium GBs. Slip transmission preferentially occurs near the non-equilibrium defects, illustrating the effect of modified GB screening characteristics due to prior dislocation transmission. The present work provides a basis for physically representative modeling of GBs and dislocation-GB phenomena in mesoscale simulations of polycrystalline plasticity.