Thermodynamic optimization of the boron-cobalt-iron system

Research highlights: → The B-Co-Fe system was thermodynamically modeled using the CALPHAD method. → The three ternary line compounds were modeled using the two sublattice model, and the liquid, fccA1, bccA2 and hcpA3 phases were modeled using the substitutional solution model. → The calculated phase diagram and thermodynamic properties agree reasonably with most of the experimental data. - Abstract: A thermodynamic optimization of the boron-cobalt-iron ternary system is performed based on thermodynamic models of the three constitutional binary systems and the experimental data on phase diagrams and thermodynamic properties of the ternary system. The liquid, fccA1, bccA2 and hcpA3 solution phases are described by the substitutional solution model. The three intermediate line compounds, (Co,Fe)B, (Co,Fe)2B and (Co,Fe)3B, are described by the two sublattice model. A set of thermodynamic parameters are obtained. The calculated phase diagram and thermodynamic properties are in reasonable agreement with most of the experimental data.