Phase equilibria and thermodynamics assessment of the Co-Fe-Nb ternary system

The Co-Fe-Nb materials system is a crucial material for magnetic applications. Despite its importance, the phase equilibria and thermodynamic characteristics of this ternary system have not been explored in detail. This study employs the Calphad method to model the phase equilibria of the Co-Fe-Nb ternary system. To obtain the ternary interaction parameters, the experimental data on the isothermal sections at temperatures ranging from 700 degrees C to 1300 degrees C was evaluated. These findings indicate that the Co-Fe-Nb system contains no ternary compound, and the (Co,Fe)7Nb6 phase exists as a single solid solution. Significant solubility of the third element in the binary compounds of Co2Nb (Laves C14) and Fe2Nb (Laves C15) is also observed. The results are in good agreement with the experimental data. Furthermore, a liquidus projection of the system is presented, for the first time, revealing eight primary solidification phases in the Co-Fe-Nb ternary system.