Thermodynamic study of phase equilibria in the Ni-Fe-B system

The phase equilibria in the Ni-Fe-B ternary system have been studied experimentally and using thermodynamic calculations. The Gibbs energy of the individual phases was described by the regular solution approximation and the two-sublattice model. The thermodynamic parameters for each phase were evaluated using the experimental data on phase boundaries obtained from differential scanning calorimetry (DSC) and other available literature data. The evaluated parameters enabled us to obtain reproducible calculations of the isothermal section diagrams. The calculated isopleth at the 26 mol% B section agreed with the DSC data obtained in this study, whereas the calculated liquidus and solidus temperatures were higher than the reported values at the Ni2B-Fe2B pseudo-binary section.