Simulation of BCC dissolution in Fe-Cr-Ni system by ICME

Integrated simulation on dissolution of the body-centered-cubic (bcc, alpha) phase in the face-centered cubic (fcc, gamma) matrix in the ternary Fe-Cr-Ni system is a first step toward the study of phase transformations in steels in the framework of integrated computational materials engineering. The accuracy of the simulation highly depends on the qualities of the thermodynamic data and atomic mobility. Firstly, the Fe-Cr-Ni system and its binary sub-systems were thermodynamically assessed by using the CALculation of PHAse Diagrams approach coupled with first-principles calculations, based on various types of thermodynamic data and phase diagrams from the literature. With the thermodynamics incorporated, the atomic mobilities and diffusivities of the fcc and bcc phases in the Fe-Cr-Ni system were then assessed. The calculated diffusion coefficients show a satisfactory agreement with the experimental data in a wide range of composition and temperature. Equipped with these requisite data, the diffusion-controlled bcc dissolution was finally simulated which well agrees with the experiments for different experimental conditions.