Can vacancies lubricate dislocation motion in aluminum?

TL;DR

This paper theoretically confirms that vacancies can facilitate dislocation motion in aluminum, providing insights into the lubrication effect and its impact on dislocation behavior in fcc metals.

Contribution

First theoretical confirmation of vacancy lubrication effect on dislocation motion in aluminum using a combined variational and ab initio approach.

Findings

Vacancies increase dislocation splitting in aluminum.

Weak, character-independent repulsion between vacancies and dislocations.

Connection established between dislocation mobility and core width.

Abstract

The interaction of vacancy with dislocations in Al is studied using the Semidiscrete Variational Peierls-Nabarro model with ab initio determined gamma surface. For the first time, we confirm theoretically the so-called vacancy lubrication effect on dislocation motion in Al, a discovery that can settle a long-standing controversy in dislocation theory for fcc metals. We provide insights on the lubrication effect by exploring the connection between dislocation mobility and its core width. We predict an increased dislocation splitting in the presence of vacancy. We find that on average there is a weak repulsion between vacancies and dislocations which is independent of dislocation character.