First-principles study of He retention and clustering in Al-Ga alloy

Understanding the effect of alloying elements on the retention and clustering behavior of Helium (He) in Aluminum (Al) is a great help to study the radiation damage process of Al-based nuclear structure materials under He irradiation. Based on the first-principles calculations, we investigated the influence of Gallium (Ga) dopant on the formation of He-n and HenV clusters in Al and Al-0.9 at% Ga (Al-Ga) alloy. We found that Ga dopant could influence the formation and growth of He clusters. In addition, the presence of Ga reduces the binding energy of both He n and HenV clusters, resulting in He dissociation from the clusters more easily. Moreover, Ga could serve as a trapping center by reducing the charge density in its vicinity to induce He nucleation in Al-Ga alloy compared to that in pure Al. Furthermore, the binding energy of He to vacancy around Ga is weaker than that around Al, suggesting that Ga will decrease the trapping capability of vacancy to He. We thus propose that Ga plays a key role in He clustering behavior. Our results are significant to understand the effect of dopant on He bubbling behavior and the distribution of damages in Al-Ga alloy under He irradiation.