Influence of MgO on the phase equilibria in the CuOx–FeOy–MgO–SiO2system in equilibrium with copper alloy – Part I: methodology and liquidus in the tridymite primary phase field

Abstract

AbstractPhase equilibria in the ‘Cu2O’–‘Fe2O3’–MgO–SiO2system in equilibrium with copper alloy have been investigated at temperatures between 1 100 and 1 250 °C. A high-temperature equilibration/quenching/electron probe micro-analysis technique has been used to accurately determine the liquid and solid compositions. The standard methodology has been modified to accurately determine the phase equilibria and liquidus in this particular chemical system. Results on phase equilibria in the tridymite primary phase field, including the tridymite–pyroxene, tridymite–spinel and tridymite–pyroxene–spinel phase boundaries, are reported. The study demonstrates the validity of the method and provides new data on the effect of MgO on the tridymite liquidus temperatures. Increasing MgO concentration was found to decrease the tridymite liquidus.