First-principles study of hydrogen and helium behavior at the TiC/V interface

Abstract

To gain insights into the nucleation of H and He bubbles at the precipitate/matrix interface, first-principles calculations have been performed to investigate the trapping and diffusion behaviors of H and He at the TiC/V interface. As for the site preference, the calculation shows that H and He prefer to occupy the V-side tetrahedral site at the interface rather than the center of the interface. Considering the H and He clusters formation, H clusters are more likely to aggregate between the first and second slab, whereas He clusters tend to aggregate at the V matrix of the first slab. The diffusion of H and He across the TiC(110)/V(100) interface demonstrates that H and He atoms can reach the favorable segregation sites at the interface from the V bulk by overcoming energy barriers of 0.23 eV and 0.59 eV, respectively. Meanwhile, trapped H and He atoms are difficult to escape from the interface. H and He atoms are, however, highly susceptible to diffusion along the interface, which means that the diffusion path can act as a fast diffusion channel. Additionally, doping Ti can facilitate the trapping of H and He at the TiC/V interface, with no significant change in the diffusion barrier for H, while reducing the diffusion barrier for He to 0.45 eV.