Journal of Phase Equilibria and Diffusion | 2021
Thermodynamic Assessment of the Co-Cr-Nb System
Abstract
In this work, the Co-Cr-Nb ternary system was evaluated using the CALPHAD technique based on the experimental measurements of the isothermal sections at 1000, 1100 and 1200\xa0°C. The solution phases including Liquid, Bcc, Fcc and Hcp were described by a substitutional solution model. The Laves phases were described by a two-sublattice model. The σ phase was described by a three-sublattice model of (Co,Nb)8Cr4(Co,Cr,Nb)18 and the μ phase was described by a four-sublattice model of Co1(Co,Cr,Nb)2(Nb)4(Co,Cr,Nb)6. The Co7Nb2 was treated as a stoichiometric compound. A set of self-consistent thermodynamic parameters for the Gibbs energies of individual phase in the Co-Cr-Nb system has been obtained which leads to a great fit between calculated results and experimented data. The calculated liquidus projection and reaction scheme of the Co-Cr-Nb ternary system have also been presented.