Mechanisms of dislocation loops influencing damage evolution of single crystal copper under uniaxial and triaxial tension

Abstract

Dislocation loops are typical irradiation defects that significantly influence the mechanical behavior of irradiated materials. In this work, molecular dynamics simulations are performed to investigate the influence mechanisms of dislocation loops on damage evolution of single crystal copper, with a focus on the effects of loading conditions (uniaxial and triaxial strain tension) and dislocation loop types (interstitial and vacancy loop). Under uniaxial strain tension, interstitial and vacancy loops exhibit distinct effects on initial plasticity but comparable effects on damage evolution. Vacancy loops induce plasticity earlier than interstitial loops, while interstitial loops exhibit faster plastic development once plasticity is activated, leading to comparable damage evolution at later stages. Under triaxial strain tension, voids nucleate directly at the sites of both dislocation loops. Vacancy loops induce void nucleation earlier than interstitial loops due to their pre-existing dislocation junctions, whereas the latter require dissociation to form such junctions before void nucleation. Additionally, the sensitivity of damage evolution to loop size depends on both loading conditions and loop types. These findings provide valuable insights into the irradiation defect-mediated damage behavior and offer mechanistic support for constructing theoretical models of irradiated materials under extreme conditions.