Computational simulation of He bubble evolution in fcc Cu with Σ3 twin boundary using object kinetic Monte Carlo method

Highlights: • The long-term evolution of a He-vacancy cluster in nano-twin Cu is investigated. • The focus is the long-term interaction between the grain boundary (GB) and defects. • We use a new simulation code based on the object kinetic Monte Carlo (OKMC) method. • The findings may explain the discrepancy in experimental and computational data. • The OKMC is a promising candidate for long-term simulation of large-scale defects. Nano-twin copper has excellent irradiation tolerance as the grain boundaries (GB) can capture and contain defects. However, the mechanism of long-term interaction between the GB and defects remains unclear, because of the extremely large computational cost of molecular dynamics simulations. In this article, a new simulation code based on the object kinetic Monte Carlo (OKMC) method is considered for investigation of the long-term evolution of the helium-vacancy (He-V) clusters in Σ3 nano-twin Cu. The results of this study confirm that the influence of the GB can only be observed when the evolution time is sufficiently long, and obvious defect enrichment effect near the GB can only be observed if the temperature exceeds 500 K. The increasing temperature can obviously decrease the He-V cluster concentration and, also, greatly increase the He pressure in the clusters, which will make them more active and unstable. The findings of this study can potentially explain the difference between experimental and computational results for He bubble evolution in nano-twin materials, and also indicates that the OKMC method is a promising candidate for long-term simulation of large-scale defects.