Phase field modeling of damage evolution in nickel-based superalloys

The failure of nickel-based superalloys, which is mainly caused by the evolution of damage, has attracted much attention. The damage evolution is highly dependent on the energy release rates and volume fractions of precipitate phase γ' in matrix phase γ. In this work, the influence of precipitate phases with different energy release rates and volume fractions on the damage evolution and the stress–strain curve is investigated by using a continuous damage phase model. It is found that the crack propagation path is almost straight when the energy release rates of the precipitate and matrix phases are close to each other. However, when the energy release rate of the precipitate phase is much larger than that of the matrix phase, the crack propagates along the interface of the two phases. Phase field simulation results indicate that the volume fraction of precipitated phase has a significant impact on the maximum fracture stress. When the volume fraction of precipitate phase increases, the fracture strength of the material is enhanced. Finally, the influence of the pre-crack on the damage evolution is also studied. It is found that the pre-crack decreases the fracture strength of the superalloys significantly. This study not only provides an effective method to predict the damage evolution of nickel based superalloys, but also explains the mechanism of the influence of precipitation and pre-crack on the failure process.