Numerical simulation of phase separation in Fe-Cr-Mo ternary alloys

The phase separation in Fe-40%atCr-5at%Mo alloy is investigated by implementing a model based on Cahn-Hilliard equation. Solute diffusion of three elements are simulated and discussed in the 2D condition. A statistical analysis is performed to investigate the microstructural change during the spinodal decomposition. A droplet-matrix pattern is achieved with the Cr rich and Mo rich droplets embedded in Fe rich matrix, and the Cr rich and Mo rich droplets have the approximatively same shape and distribution. The number and average size of Cr rich and Mo rich droplets keep changing with a decreased change rate, and the size distribution of droplets has a significant change with time. The concentration distributions of Cr and Mo are different and form core-shell structures in the Fe rich matrix. Temperature is an active promotion factor to the phase separation in Fe-40%atCr-5at%Mo alloy. Simulated diffusion behavior of Mo and Cr in Fe-Cr-Mo ternary alloys is in good agreement with that predicted by the theory.