On the Variability of Grain Boundary Mobility in the Isoconfigurational Ensemble

TL;DR

This study uses molecular dynamics simulations to quantify how local microstructure and initial velocity conditions cause variability in grain boundary mobility in nickel, revealing significant impacts of initial conditions on grain growth behavior.

Contribution

It introduces a dynamic propensity analysis to identify sources of variability in grain boundary mobility, emphasizing the role of initial velocity distributions.

Findings

Large variation in grain boundary mobility depending on boundary conditions

Initial velocity distribution significantly affects grain boundary motion

Dynamic propensity analysis reveals sources of mobility variability

Abstract

Recent grain growth experiments have revealed that the same type of grain boundary can have very different mobilities depending on its local microstructure. In this work, we use molecular dynamics simulations to quantify uncertainty in the reduced mobility of curved grain boundaries for different types of boundary conditions and over a range of initial velocity seeds. We consider cylindrical island grains in Ni with a [001] tilt axis as a model system. Unexpectedly, we find large variation in the reduced mobility of curved grain boundaries depending on both the imposed constraints and the initial velocity distribution. We perform a dynamic propensity analysis inspired from studies of glass forming liquids to analyze sources of variation in reduced mobility. Our work highlights the significant impact of initial velocity distributions on grain boundary motion which has not been analyzed in prior work.