The calculation models of macroscopic temperature field and microstructure phase field of Ni-based single crystal superalloy during directional solidification were established. The temperature fileld change of single crystal rod during directional solidification was simulated. Based on the macroscopic temperature field

the growth of microstructure was simulated. The microstructure of nickel-base single crystal superalloy was compared with the simulation results to verify the accuracy of the calculation model. Both the simulation and experimental results indicate that the dendrite morphology in different regions of single crystal rod after directional solidification has significant difference. The dendrite under high cooling rate presents small primary dendrite arm spacing

while that under low cooling rate is quite coarse

with well-developed primary and secondary dendrite arm as well as large primary dendrite arm spacing.