Phase-field simulation of γ"(D022) precipitation in Ni base superalloys

Although the gamma ''(D0(22)) phase has been known as a strengthen phase for the turbine disk of wrought Ni-base superalloys, the computer simulation of the gamma ''(D0(22)) precipitation is hardly performed. In this study, it is demonstrated that the phase-field modeling of the complex microstructure developments including gamma ''(D0(22)) precipitation in Ni-V-X (X=Co,Nb,Fe) alloys. The simulation results obtained are as follows: (1) The complex morphologies of the gamma(Al)+gamma ''(D0(22)) two-phase microstructure, such as the maze-micro structure, the. chessboard-microstructure, and the chessboard-like microstructure, in Ni-V-X (X=Co,Nb,Fe) alloys are simulated reasonably by using phase-field method. (2) The morphology of the microstructure is mainly controlled by the elastic strain energy induced from the lattice mismatch. In particular, the tetragonal distortion is a key parameter to control and understand the complex microstructure changes.