Absorption and adsorption of hydrogen in B2-FeAl: Ab initio study

Using the density functional theory and the pseudo-potential approach, the behavior of atomic hydrogen in bulk and surface of B2-FeAl was studied. In Al-rich environment without structural defects, the hydrogen atom prefers to stabilize in octahedral site. However, the most favorable double defect cases were hydrogen with Al-vacancy followed by hydrogen with Al-antisite. For the surface case, the obtained results have shown that H was always attracted by (0 0 1) and (1 1 0) surfaces. The diffusion of H to the bulk was predicted to be favorable for (1 1 0) and unfavorable for (0 0 1) Fe-terminated. The behavior of H in B2-FeAl H was highly dependent on the local environment and the surface orientation.