Prediction of Rafting Kinetics of Practical Ni-Based Single-Crystal Superalloys

Abstract

Directional coarsening of γ′ phase (rafting) in Ni-based single-crystal superalloys during tensile creep at 1273 K is simulated by the phase-field (PF) method. A number of PF simulations are performed with various values of PF model parameters. The obtained results are used to train a neural network (NN) to enable fast and accurate prediction of the rafting time (traft) from the values of model parameters. Material parameters of first-, second-, third-, and fourth-generation superalloys are estimated from their chemical compositions for predicting traft using the trained NN. The traft of several practical superalloys are predicted in the tensile stress range of 130–190 MPa. The NN prediction results show that traft tends to be longer along with the order of alloy generation. Furthermore, creep rupture time (trup) of practical superalloys is estimated based on the Larson–Miller parameter method. It is found that there is a positive correlation between traft and trup, and the correlation becomes stronger with increasing the magnitude of external tensile stress.