Phase Diagram and Thermodynamic Properties of Cu-O Binary System

Thermo-Calc software is used to reassess the equilibrium temperature-composition phase diagram at 1 atm and to deduce the thermodynamic properties of Cu-O binary system at T = 1500 K. The phase diagram showed one single phase which is the non-stoichiometric Cu ionic liquid other than elemental Cu and O at the terminals, in addition to Cu2O and CuO which can be considered as stoichiometric line compounds. There are nine fields of two mixed phases, two eutectic reactions, one monotectic reaction, and a miscibility gap. The solubility of oxygen in copper and that of copper in oxygen are determined. The molar Gibbs energy and molar enthalpy curves of the Cu2O-CuO ionic solution are plotted against mole fraction oxygen at 1500 K. The natural logarithm of the activity is plotted against oxygen mole fraction for oxygen and copper in the melt, and the activity coefficients are determined.