Crystallographic orientation and hydrostatic pressure dependent elastic and stacking-fault properties of γ-Ni/γ′-Ni ₃ Al phase interfaces: A comparative first-principles investigation

Ni-based single-crystal superalloys with γ-Ni+γ′-Ni 3 Al dual-phase structure are critical materials for aerospace and power applications due to exceptional hightemperature performances. Under service conditions, the undergoing extreme pressure may strongly affect structural, mechanical and deformation behaviors of the superalloys. However, the responses of γ/γ′ interfaces to hydrostatic pressure remain unclear compared with the bulk constituents. In this study, first-principles calculations were performed to investigate the structural, elastic, stacking-fault and electronic properties of the (001), (110) and (111) γ/γ′ interfaces within 0–50 GPa, by comparing with the bulk phases γ-Ni and γ′-Ni 3 Al. We found that the γ/γ′ interfaces were mechanically stable under pressure, with elastic constants and moduli and unstable stacking fault energy (γ usf ) increasing monotonically with pressure. Elastic constant analysis revealed that the (111) interface exhibited the greatest enhancement in axial stiffness under pressure, with the corresponding increases in elastic moduli being more pronounced than those of the other orientations. The increasing barrier for dislocation nucleation and dissociation as indicated by increasing energy difference γ usf – γ isf manifested the pressure-induced strengthening of the (111) interface and bulk phases. Planar charge density analysis revealed pressure-induced electron redistribution and strengthened interfacial bonding, offering further microscopic insights into the interfacial behaviors under pressure and guidance for designing advanced Ni-based superalloys for highpressure applications.