CALPHAD/first-principles re-modeling of the Co-Y binary system

The thermodynamic properties and phase diagram of the Co-Y system have been analyzed by the CALPHAD technique using a computational optimization procedure via the ThermoCalc software package. Based on the experimental data, nine intermetallic phases were taken to be stoichiometric compounds and two phases, Co5Y and Co17Y2 were described with three-sublattice models. First-principles calculations were obtained for the enthalpy of formation of five stable Co-Y compounds and the calculated end members of the Co5Y phase. The model accounts for the magnetic contribution of Co7Y2, Co5Y and Co17Y2. The thermochemical and equilibrium information in the CoY system has been accurately reproduced and is shown to be in agreement with all experimentally validated phase reactions.