Ab initio study of strain-driven vacancy clustering in aluminum

TL;DR

This study uses first-principles density functional theory to explore how hydrostatic strain influences vacancy clustering and dislocation loop formation in aluminum, revealing strain thresholds for cluster collapse and dislocation nucleation.

Contribution

It provides new insights into the atomic-scale mechanisms of vacancy clustering and dislocation loop formation driven by strain in aluminum using ab initio calculations.

Findings

Compressive strains promote vacancy aggregation and cluster collapse.

Heptavacancies on the (111) plane collapse into dislocation loops under >5% strain.

Strain-driven vacancy behavior aligns with experimental observations.

Abstract

We present a first principles investigation of strain-driven vacancy clustering in aluminum. Specifically, we perform Kohn-Sham density functional theory calculations to study the influence of hydrostatic strains on clustering in tri-, quad-, and heptavacancies. We find that compressive strains are a key driving force for vacancy aggregation, particularly for collapse of clusters on the (111) plane, consistent with prior experimental observations of vacancy clusters on this plane. Notably, we find that the heptavacancy on the (111) plane collapses to form a prismatic dislocation loop for hydrostatic compressive strains exceeding 5\%, highlighting the critical role of such strains in prismatic dislocation loop nucleation in aluminum.