Hydrogen diffusion near saturation solubility in α-U: An ab initio molecular dynamics study

A fundamental understanding of the diffusion behavior of hydrogen (H) near saturation solubility in Uranium (U) metal is crucial for comprehending the hydrogen embrittlement in U and its alloys. This study employs first- principles molecular dynamics simulations to investigate the diffusion behavior of hydrogen near saturation solubility in alpha-U crystal. In alpha-U, H atoms hop between Pentahedral pyramid centers interstices and tetrahedral interstices. We gave the diffusion coefficients of H in alpha-U with different hydrogen concentrations, which are consistent with other experimental and calculational values. As the concentration of hydrogen increases, the diffusion coefficient increases, which is likely due to the lower energy barrier for hydrogen diffusion. Additionally, we confirmed that hydrogen atoms diffuse freely in our simulated system rather than forming hydrides.