Alloying induces directionally-dependent mobility and alters migration mechanisms of faceted grain boundaries

TL;DR

This study reveals that alloying induces directionally-dependent mobility in faceted grain boundaries, with solutes affecting migration mechanisms differently depending on the migration direction, uncovering a new form of chemically-induced anisotropy.

Contribution

It introduces a novel understanding of how solutes influence the migration and mobility of faceted grain boundaries in a direction-dependent manner.

Findings

Solutes segregate to facets with more free volume.

Boundary velocity is reduced in one migration direction due to solutes.

A new mechanism allows boundary migration to escape solute pinning, increasing speed.

Abstract

Faceted grain boundaries exhibit unusual segregation and migration tendencies. To gain a deeper understanding of how solute atoms interact with faceted interfacial structures during migration, this study probes the migration behavior of a faceted $\Sigma$11 boundary in Cu doped with Ag atoms. The solutes are found to segregate to the facet with more free volume and strongly reduce boundary velocity in one migration direction, but not the other, due to the presence of a directionally-dependent motion mechanism that can escape solute pinning and therefore speed up migration. Hence, a new mechanism of chemically-induced anisotropy in grain boundary mobility is uncovered by these simulations.