Thermodynamic modeling of liquidus surface of the phase diagram of Cu2O–Al2O3–ZrO2 system

Abstract

Calculations of the liquidus lines for the phase diagrams of the Cu2O–Al2O3, Cu2O–ZrO2 and Al2O3–ZrO2 binary systems were made as well as the calculations of liquidus surface for the phase diagram of the Cu2O–Al2O3–ZrO2 ternary system. The theory of subregular ionic solutions was used in thermodynamic modeling. The values of the theory parameters Q, thermodynamic characteristics (melting temperature, heat of fusion, and entropy of fusion) for CuAlO2 compound were determined. The values of the equilibrium constants of the transition from solid to liquid for Cu2O, Al2O3, ZrO2 and CuAlO2 were defined. Calculations of activity of Cu2O, Al2O3, and ZrO2 in the oxide melt for Cu2O–Al2O3 and Cu2O–ZrO2 diagrams show that a(Cu2O) , a(Al2O3 ) and a(ZrO2 ) have negative deviation from Raoult’s law. The calculated activity of the aluminium oxide has good agreement with the literature. Construction of the liquidus surface for the Cu2O–Al2O3–ZrO2 ternary system allows to define the points of the nonvariant transformation. Results of the thermodynamic modeling of the Cu2O–Al2O3–ZrO2 ternary system show that equilibrium “oxide melt–pure solid copper oxide–pure solid aluminium oxide” is realized in this system. This equilibrium is not characteristic for Cu2O–Al2O3 binary system. Results of this work can be used for the analysis of the bronze production and for the analysis of slag behavior for the copper and copper-based alloys industries.