Thermodynamic study on the Ca-Tb4O7-Fe system

The changes of the standard Gibbs free energy and Gibbs free energy for the reactions of 7Ca+Tb4O7=4Tb+7CaO and Tb+2Fe=TbFe2, and equilibrium vapar pressure of Ca and vapor pressure of Ca in the above reation system were calculated. The thermodynamics calculation and experiment proved that the redution-diffusion production must be TbFe2 in the Tb-Fe binary alloy.