Decomposition of low-angle grain boundaries

Abstract

Grain boundaries (GBs) merge and grains disappear during microstructure evolution. However, the Peach-Koehler model predicts that particular stress states may reverse such a process by exerting differential Peach-Koehler forces on different dislocations. This work considers this reversal as GB decomposition and illustrates it in a low-angle asymmetric tilt GB and a low-angle mixed tilt-twist GB via atomistic simulation. In both cases, the dislocations separate into two GBs separated by a new grain. This work describes the requirements for decomposition and the importance of dislocation separability. Additionally, we examine the dislocation behaviors and stress signatures associated with this process, along with the impact of strain rate and temperature on those aspects.