Studying hydrogen effect on the core structure and mobility of dislocation in nickel by atomistically-informed generalized Peierls-Nabarro model

Hydrogen (H) atoms in the metallic crystalline lattice interact with the pre-existing dislocations and then remarkably affect the plastic deformation of metals. Thereby quantitatively characterizing the H-dislocation interaction is of great importance for understanding H-induced plasticity and failure. Most of the previous studies have focused on the long-range interaction between hydrogen and dislocation, but rarely considered the short-range interaction, especially the hydrogen effect on the dislocation core structure. Here, with the aid of the H-affected gamma-surface calculated from atomistic modeling, an atomistically-informed generalized Peierls-Nabarro model is employed to study the hydrogen effect on the core structure of dislocation, the recombination energy of the extended screw dislocation, and the Peierls stress in nickel. Our results show that, on the one hand, hydrogen can decrease the stable stacking fault energy, leading to the increase of the stacking fault width for both extended edge and screw dislocations. Consequently, the recombination energy of extended screw dislocation is increased, indicating that hydrogen can suppress the cross-slip of screw dislocation and facilitate the slip planarity observed frequently in experiments. On the other hand, hydrogen can increase the unstable stacking fault energy, implying that hydrogen can inhibit the nucleation of partial dislocations. Moreover, hydrogen in the dislocation core increases the Peierls stress and thus increases dislocation slip resistance. Finally, quantitative relations between the Peierls stress and hydrogen concentration are given. These results are of great significance for understanding the H-affected dislocation plasticity mechanisms, and can be used for quantifying the hydrogen effect on dislocation dynamics.