Combined Process- and Phase-Field-Simulation to Predict the Microstructure of Single-Crystal Ni-Based Superalloys

A model for the prediction of the dendrite structure in single crystal Ni-based superalloys is established. A combined approach of finite element simulation (FEM) of the temperature conditions during the casting process and phase field simulation of solidification is used to determine the influence of withdrawal rates between 0.5 and 10 mm·min−1 on dendrite spacing of CMSX-4 and CM186LC. The model is compared with experimental data from literature, showing good agreement and thus great potential for predicting other parameter sets. Furthermore the influence of wall thicknesses between 0.4 and 2.0 mm was determined for these alloys. The reduction in dendrite spacing with decreasing wall thicknesses can also be predicted by the solidification model. The lack of competition between neighboring dendrites in the volume close to the surface plays a decisive role.