Thermodynamic assessment of the Ni–Co-Re system and diffusion study of its fcc phase

Abstract

In the present work, the first-principles calculations were performed to study the enthalpies of mixing and the magnetic moments of the solid solutions in the Ni–Re and Co–Re systems. Meanwhile, the phase equilibria of the binary Ni–Re, Co–Re and ternary Ni–Co-Re alloys were investigated using equilibrated alloys and diffusion couples. Various types of data from the present work as well as the literature were used to perform a thermodynamic assessment of the ternary Ni–Co-Re and sub-binary systems using the CALPHAD method. Based on the present thermodynamic parameters, the atomic mobilities for the fcc phase in the Ni–Re and Co–Re systems were reassessed to reproduce experimental data in the literature. Furthermore, several ternary Ni–Co-Re diffusion couples were assembled and annealed at 1273 K and 1473 K to deduce the interdiffusion coefficients. On the basis of diffusion experimental data from the present work and the literature, atomic mobilities of Ni, Co, and Re in the fcc Ni–Co-Re system were assessed coupled with the present thermodynamic description. The accuracy of the assessed atomic mobilities was confirmed by comparing with the experimental interdiffusion coefficients, composition profiles and diffusion paths.