Effect of pinning particles on grain boundary motion from interface random walk

Abstract

Impurities can dramatically influence grain boundary migration, thereby impacting material properties. In this letter, we present a theoretical model for grain boundary motion in the presence of embedded particles using the interface random walk approach. Based on the fluctuation-dissipation relation, we derive an analytical expression relating the grain boundary fluctuations to the boundary mobility and key parameters governing the drag effect of the particles. In addition to predicting the modified boundary mobility due to pinning particles, the model provides a way to estimate the force acting on the particle-boundary interface from atomistic simulations. The theory facilitates an enriched analysis of atomistic simulations of a grain boundary with embedded particles, revealing that a pinned grain boundary exhibits a response akin to tethered Brownian motion.