Unified dislocation-informed crystal plasticity-phase field fracture model for nickel-based single crystal superalloys across wide temperatures

Fracture of nickel-based single crystal superalloys across wide temperature regimes is a primary concern in aeroengine component design and service. The temperature-dependent mechanical behavior and failure mechanisms pose significant challenges for establishing a unified model applicable over broad temperature ranges. This study proposes a two-phase dislocation-informed crystal plasticity-phase field framework to achieve a unified description of evolving physical mechanisms across a wide temperature spectrum. Four distinct damage mechanisms, including cleavage and slip in the γ' phase, and slip and voiding in the γ phase, are integrated within a single thermodynamically consistent system. The temperature-dependent plastic deformation of the γ and γ' phases is attributed to the activity of seven types of dislocation motion, all of which are incorporated into the constitutive equations. The continuous evolution of edge and screw dislocation densities in both phases leads to variations in dislocation configurations, which serve as microscopic carriers of damage and directly govern the evolution of phase field variables, thereby triggering crack initiation and subsequent propagation. The main contribution of this work lies in the first development of a two-phase model accounting for both edge and screw dislocation evolution in nickel-based superalloys, along with a unified treatment of four distinct damage mechanisms. This approach physically bridges microscopic dislocation behavior, mesoscopic deformation, and macroscopic fracture across a wide temperature spectrum.