ALUMINUM OXYGEN EQUILIBRIUM BETWEEN CAO-AL2O3 MELTS AND LIQUID-IRON

Aluminium-oxygen equilibria between CaO-Al2O3 melts and liquid iron were studied in the temperature range of 1 823 to 1 923 K, using an alumina and lime crucibles. The equilibrium constant K for the reaction: 2Al + 30 = Al2O3 was discussed with reference to the supersaturation for nucleation of alumina, and compared with the previous experimental and thermodynamic data. The supersaturation was observed in the experiments in which an Fe-Al alloy with low concentrations of initial oxygen was used under the condition of no stirring. Supersaturation increased with a decrease of oxygen content in liquid iron. Two types of alumina inclusions with a size of 2-5-mu-m and below 0.1-mu-m were observed by SEM.