Disentangling the Effects of Curvature and Misorientation on the Shrinkage Behavior of Loop-Shaped Grain Boundaries

TL;DR

This study investigates how curvature and misorientation influence the shrinkage of loop-shaped grain boundaries in 2D colloidal crystals, revealing complex behaviors that challenge existing geometric predictions and enhance understanding of polycrystal coarsening.

Contribution

It provides new insights into the interplay of curvature and misorientation on grain boundary shrinkage, highlighting a transition in kinetics and the role of dislocation dynamics.

Findings

Shear coupling decreases with increasing misorientation, contrary to predictions.

A transition in shrinkage kinetics occurs between small and large loops.

Dislocation annihilation enhances sliding, affecting boundary behavior.

Abstract

The material properties of polycrystals are strongly affected by the evolution and coarsening of their internal grain structures. Yet, studying this process is challenging due to the complex interactions within grain boundary networks. Here, we systematically investigate the shrinkage of isolated loop-shaped grain boundaries in 2D colloidal crystals. Unexpectedly, we find that shear coupling decreases with increasing grain misorientation, contrary to geometric predictions. This counterintuitive result is attributed to enhanced concurrent sliding driven by the annihilation of dislocations. Furthermore, by focusing on the evolution of the grain size, we reveal a transition in shrinkage kinetics between small and large loop sizes, offering an explanation for previously observed discrepancies in grain boundary mobility. These findings reveal a more intricate dependence of grain boundary behavior on curvature and misorientation than previously reported, offering new insights into polycrystal coarsening dynamics.