Hydrogen-Reduced Dislocation Line Tension in the Face-Centered Cubic Nickel

Abstract Dislocation line tension Γ is a critical property inherent to continuum scale plasticity models of metal during the hydrogen embrittlement process. In this study, we employ atomistic simulations combined with hybrid grand canonical Monte Carlo and molecular dynamics methods to systematically investigate the effects of hydrogen on edge and screw dislocations in the face-centered cubic Ni. Hydrogen was found to preferentially segregate to tensile regions, resulting in a reduction of dislocation line tension. To capture the kinetics of curved dislocation motion, we proposed an effective Peierls stress formalism for bow-out configurations, allowing the separation of intrinsic lattice resistance from hydrogen-induced effects. The results reveal a dual mechanism: at low hydrogen concentrations, line tension softening promotes dislocation bow-out; at high concentrations, hydrogen drag dominates and suppresses dislocation mobility. This work provides fundamental insights into hydrogen–dislocation interactions and highlights the complex behavior of hydrogen embrittlement.