Misfit-dependent interaction mechanisms between γ-phase dislocations and interfacial dislocation networks in nickel-based single crystal superalloys under [001] tensile loading

Understanding the dislocation–interface interaction mechanisms at atomic-scale is crucial for improving the temperature capacity of Ni-based single-crystal superalloys. This study develops an atomistic model challenging yet closer to real superalloys to investigate the interaction between a 1/2[1 1 0] screw dislocation on γ {1 1 1} plane and γ/γ’ interfacial dislocation network under [0 0 1] tensile stress via molecular dynamics simulations. Negative lattice misfits are explicitly incorporated into the γ/γ’ slab models by using Re- and temperature-dependent lattice constants, enabling realistic representations of interfacial geometry and stress. The simulations reveal two distinct misfit-controlled interaction modes during isothermal relaxation. One involves the formation of Lomer–Cottrell locks under low absolute misfit condition, and the other is characterized by dislocation loop evolution and delayed absorption under high absolute misfit. These modes obviously influence the early-stage dislocation behavior leading to maximum stress under uniaxial tensile loading. Moreover, the maximum tensile stress occurs simultaneously with the complete decomposition of the misfit dislocation network, thereby causing local necking within the γ phase. Parametric regression analysis further indicates that temperature, Re content and misfit jointly modulate the deformation of γ-γ’ at high temperature. These findings are expected to provide theoretical insights for interface stability and mechanical behavior in advanced superalloys.