Thermodynamic and atomic mobility assessment of the Co–Fe–Mn system

The phase equilibria and diffusivity of Co–Fe–Mn system were investigated using alloy equilibrium and the diffusion couple technique. Furthermore, thermodynamic properties and diffusion mobilities were assessed using the CALPHAD approach. Isothermal sections of the ternary phase diagrams of the Co–Fe–Mn alloy at 800, 900, and 1000 °C were obtained. The phase boundaries between face-centered cubic (fcc)/A13 were experimentally determined for the first time, whereas those between fcc/body-centered cubic were similar to those reported in previous studies. The thermodynamic parameters of the A13 phase were assessed based on these results. The phase diagrams obtained using the thermodynamic interaction parameters in this study are in accordance with the experimental results. The diffusion paths of the fcc Co–Fe–Mn ternary systems at 900, 1000, and 1100 °C were experimentally determined, and the interdiffusivities were evaluated from the composition-penetration profiles using the Whittle–Green method. The interdiffusion coefficients and penetration profiles were calculated using the assessed atomic mobility parameters. The calculated interdiffusion coefficients and penetration profiles agreed with the experimental ones, validating the values of the optimized atomic mobility parameters. Graphical abstract