Equation of motion for grain boundaries in polycrystals

Grain boundary (GB) dynamics are largely controlled by the formation and motion of disconnections (with step and dislocation characters) along with the GB. The dislocation character gives rise to shear coupling; i.e. the relative tangential motion of two grains meeting at the GB during GB migration. In a polycrystal, the shear coupling is constrained by the presence of other grains and GB junctions, which prevents large-scale sliding of one grain relative to the other. We present continuum equations of motion for GBs that is based upon the underlying disconnection dynamics and accounts for this mechanical constraint in polycrystals. This leads to a reduced-order (zero-shear constrained) model for GB motion that is easily implemented in a computationally efficient framework, appropriate for the large-scale simulation of the evolution of polycrystalline microstructures. We validated the proposed reduced-order model with direct comparisons to full multi-disconnection mode simulations.

Automated summary

This study proposes continuum equations of motion for grain boundaries based on disconnection dynamics, accounting for mechanical constraints in polycrystals to develop a zero-shear constrained model for grain boundary motion. The model is easily implemented in a computationally efficient framework and suitable for large-scale simulation of polycrystalline microstructure evolution. Validation of the proposed model was conducted through direct comparisons with full multi-disconnection mode simulations.