The effects of alloying elements on hydrogen-affected generalized stacking fault energy and dislocation behavior in nickel-based alloys

Nickel-based alloys are widely used in applications requiring high toughness and ductility. However, the susceptibility of these alloys to hydrogen embrittlement (HE) presents a significant challenge. In this study, first-principles calculations were employed to investigate the generalized stacking fault energy (GSFE) in nickel doped with various alloying elements, including Al, Cr, Cu, Fe, Mn, Mo, Nb, Ti, and W. The semi-discrete variational Peierls-Nabarro model was used to explore the effects of hydrogen and alloying elements on dislocation core width, Peierls stress, and homogeneous dislocation nucleation stress. This research has revealed that the doping of all alloying elements reduces the intrinsic stacking fault energy of Ni, which promotes coplanar slip of dislocations and increases the risk of HE. However, doping also alters the interaction between dislocations and hydrogen. The majority of alloying elements can weaken the binding energy between hydrogen and dislocations and increase the Peierls stress for dislocation slip, thereby inhibiting hydrogen migration through dislocations and hydrogen-induced plastic flow. Notably, Fe, Cr, and Mn exhibit an inhibitory effect on dislocation nucleation at the presence of hydrogen. We have also discovered that the stress required for dislocation nucleation is significantly influenced by the width of the dislocation core, while it is less affected by the stacking fault energy. Previous computational and experimental studies have predominantly emphasized the influence of intrinsic stacking fault energy on HE. This research elucidates that alloying elements can enhance the material's resistance to HE by modifying the properties of dislocations. These findings provide a deeper understanding of the complex mechanisms behind HE in nickel-based alloys and offer insights for designing materials with improved resistance to hydrogen-induced degradation. • First-principles calculations were used to study hydrogen embrittlement in nickel-based alloys. • Hydrogen lowers stacking fault energy in Ni, promoting localized plasticity and crack propagation. • Cr, Mn, and Fe reduce hydrogen-induced dislocation multiplication, matching prior experiments. • Alloying raises Peierls stress and lowers dislocation mobility, mitigating hydrogen's effect. • Results provide guidance for designing Ni alloys with improved hydrogen embrittlement resistance.