He clustering and role of vacancy in CuZr system

Helium-induced degradation of structural materials is a major concern for materials operating for a long time under extreme radiation environments. In order to prevent such degradation, it is important to understand how He interacts with the host material as well as with itself inside the host environment. The presence of defects such as vacancies and their interaction with He is also important here as these defects may act as a source of nucleation for the clustering of He inside the material. In this study, we have performed ab initio calculations to investigate the behaviour of He inside CuZr crystalline alloy in the B2 phase with equal atomic ratio. The formation of metallic vacancy, He interstitial, and vacancy-He complex have been investigated systematically to understand the trapping and binding behaviour of He. Our results reveal that He interstitials play a significant role in determining the formation of Cu and Zr vacancy and the presence of vacancy in the material attracts more He towards it.