Energetic and structural stability of vacancy clusters in Al under external stress conditions

Abstract

In this study, we investigated the structural stability and energetic behavior of void-type, plate-like, and stacking fault tetrahedra (SFT) vacancy clusters in Al under varying tensile and compressive stress conditions. Our results demonstrate that void-type and plate-like clusters maintain their structures under tensile stress, which energetically favors the aggregation and growth of isolated vacancies. However, compressive stress induces structural transitions in these clusters, reducing their stability. In contrast, SFT clusters retain their characteristic configuration under both tensile and compressive stress. While compressive stress promotes SFT formation and growth, tensile stress hinders vacancy aggregation, making SFTs less stable under tension. Comparatively, SFT clusters are the most stable under compressive stress, while void-type clusters become the most stable under high tensile stress. These findings provide critical insights into the stress-dependent behavior of vacancy clusters, with implications for defect engineering in materials subjected to external stress, offering a deeper understanding of vacancy cluster stability and growth mechanisms across different stress regimes.