Numerical simulation of microstructure evolution in Ni-based superalloys during P-type rafting using multiphase-field model and crystal plasticity

During the service process, Ni-based superalloys undergo microstructure evolutions such as rafting, which greatly affect its service performance. In the present study, a multiphase-field model coupled with crystal plasticity was established to simulate the gamma/gamma' microstructure evolution of Ni-based superalloys during P-type rafting. The anisotropic plasticity considering 12 octahedral slip systems was defined in gamma matrix channel. The PanNickel (c) database was used to calculate thermodynamic and kinetic data for phase transition and diffusion in multicomponent superalloys. First, the model was validated by two benchmarks with and without consideration of external load respectively. Then, the anisotropic of slip systems was analyzed. It was found that eight slip systems A2, A3, B2, B4, C1, C3, D1, D4 were activated in gable channel first when the structure was compressed in [0 0 1] direction. Besides, the elements distribution was studied. It can be seen that Al, Ti, Ta diffused into precipitates while Co, Cr and Mo diffused away the roof channel when the structure was compressed in [0 0 1] direction. Re and W mainly distributed in the gamma/gamma' interface because their slow diffusion rate. Finally, the P-type raft of CMSX-4 superalloy was simulated, and the plasticity distribution and plastic behavior of the 12 slip systems were discussed. The current model can be used to simulate phase transformation of multicomponent superalloys where plasticity is strongly coupled.