Effects of applied mechanical strain on vacancy clustering in FCC Ni

TL;DR

This study uses molecular dynamics simulations to explore how mechanical strain influences vacancy clustering in FCC Ni, revealing strain-dependent stable vacancy structures and the importance of entropy in their thermodynamic stability.

Contribution

It provides new insights into the effects of mechanical strain on vacancy cluster stability and transitions in FCC Ni, emphasizing the role of entropy in these processes.

Findings

Hydrostatic strain causes different stable vacancy clusters in FCC Ni.

Strain magnitude influences the transition between SFTs and voids.

Entropy significantly affects the thermodynamic stability of vacancy clusters.

Abstract

Irradiation-induced vacancy evolution in face-centered cubic (FCC) Ni under mechanical strains was studied using molecular dynamics simulations. Applied hydrostatic strain led to different stable forms of vacancy clusters, i.e., voids under strain >= +2% and stacking fault tetrahedras (SFTs) under strain <= 0. Direct transitions between SFT and void revealed that increasing strain magnitude facilitated the thermodynamic stability and dynamical evolution. The estimated free energy difference could well validate the dynamical simulations results by accounting for entropic contribution, which was revealed to play an important role in the thermodynamic stability of vacancy clusters in FCC Ni.