Solute influence in transitions from non-Arrhenius to stick-slip Arrhenius grain boundary migration

Abstract

Synthetic driving force based molecular dynamics simulations are used to evaluate the grain boundary velocities for an incoherent Σ3 [111] 60° {11 8 5} GB in elemental nickel and its copper-based alloys in the dilute limit. We examine the effects of temperature, solute content, and magnitude of the driving force on grain boundary velocity trends and their associated mechanisms. We observe that, for pure nickel and its copper alloys in the dilute limit at high driving forces, these special grain boundaries exhibit non-Arrhenius or anti-thermal migration behavior, where temperature and grain boundary velocity are inversely related. For lower driving forces, the increased copper content leads to stick-slip migration behavior and a likely transition from non-Arrhenius to Arrhenius temperature dependence. Interestingly, the ordered atomic motions are frustrated but unchanged by the solute content and stick-slip migration. While the results are generally consistent with the Cahn-Lücke-Stüwe (CLS) model, no solute drag is observed; rather, the solute effects are likely the result of solute pinning.