Abstract Scope |
During the interaction between a queue of dislocations and grain boundaries (GBs) in materials, a dislocation pileup usually forms, which in turn, significantly modifies the local stress state. This process is multiscale in nature since both the atomistic GB structure and the long-range stress induced by the dislocation accumulation near the GB come into play in the subsequent structure change. Taking the Ti-alloy as a model material, here we present a concurrent atomistic-continuum method for (i) measuring not only the local Cauchy stress but also the couple stress ahead of a long-range dislocation pileup; and (ii) determining their roles in the subsequent structure change, such as phase transformation, twinning, and fracture, caused by the dislocation-GB reaction. Our results elucidate the discrepancies between fully atomistic simulations and experimental observations of dislocation-GB reactions, and highlight the importance of directly modeling dislocation-GB interactions using concurrent multiscale approaches. |