A theoretical study of the effects of sp-elements on hydrogen in nickel-based alloys

Abstract

By using first-principles calculations, we present a theoretical study of the interactions between hydrogen (H) and sp-elements from the 3rd, 4th and 5th period (Al, Si, P, S, Ga, Ge, As, Se, In, Sn, Sb and Te) in nickel-based alloy. The interactions between H and sp-atom are evaluated by the calculated interaction energy. Judged by the interaction energy, H is repelled by all these elements (except S) in nickel-based alloy. The atomic and electronic structures are analyzed. Especially, the interaction energy is found to be closely related with the electronic structure and electronegativity. The larger the electronegativity of the sp-elements, the weaker the H-sp bond. The weaker H-sp bond results in the more positive interaction energy and the repulsion to H. Particularly, for the cases of S and Se, the long HS and HSe distances can largely relieve the strain effect induced by the insertion of the H atom, thus decrease the repulsion to H. The interaction energy for S is even reduced to a negative value, which means that H is attracted in the NiSH system. Our work presents a fundamental understanding of the effects of the sp-elements on H in nickel-based alloys systematically.