Thermodynamic description of phase equilibria in the Cu-Al-Zr-O system under the condition of metal melt existence

Thermodynamic modeling and experimental investigation of phase equilibria in the Cu-Al-Zr-O system were carried out. Thermodynamic analysis of phase equilibria was performed using the method of constructing the Surface of Components Solubility in the Metal melt (SCSM). Thermodynamic analysis was made for temperatures of 1200 and 1300 °С. The areas of phase equilibria of liquid metal with conjugated oxide phases were constructed depending on concentrations of elements dissolved in metal melt. Formation of copper oxide and CuAlO2 compound in the presence zirconium and aluminum in liquid metal melt are thermodynamically unlikely. The areas of these phase equilibria are offset to less than 10-13 wt. % Al and to less than 10-20 wt. % Zr. Iso-oxygen sections have been also calculated. It was shown that zirconium is a stronger reducing agent than aluminum in the copper melt. Thus the alternative deoxidation mechanism is characteristic for the Cu-Al-Zr-O system. Zirconium dissolved in the copper melt will primarily interact with oxygen. Aluminum oxide may be formed at lower zirconium concentration and at sufficient oxygen concentration in copper melt. Zirconium concentration in copper melt will be decreased in connection with formation zirconium oxide. Experimental investigations confirmed thermodynamic modeling results. The analyses of the non-metallic inclusions have been performed using scanning electron microscope and energy dispersion spectrometer. The research results may be interesting for copper and copper alloys industry.