Oxygen Solubility in Molten Sm-La-O Alloys and Equilibrated Oxide Phases

Abstract

In this study, the solubilities of oxygen in molten Sm-La-O alloys were measured and the equilibrium oxide phases yielded from the alloys when they were in the temperature range of 1473-1673 K were identified. Sm₂O₃ oxide pellets and Sm-La-O alloy were held at a fixed temperature above melting point of the alloy. Then the samples were quenched into water. The oxygen solubility of Sm-La-O alloy was determined by measuring oxygen concentration in the quenched alloy phase using inert gas fusion infrared absorption spectroscopy. The oxygen solubility increased with the increase in temperature and the composition of Sm. The composition and crystal structure of the oxide after quenching were analyzed using scanning electron microscope with energy dispersive X-ray spectroscopy and X-ray diffraction; The results indicated that hexagonal (A-type) or monoclinic (B-type) (La, Sm)₂O₃ stably existed in the molten alloy at high temperatures. Larger values in Sm/(Sm + La) ratio were identified in the oxide phase than that in the Sm-La-O alloy.

Fig. 4　Change in oxygen solubility in molten Sm-La-O alloy with Sm concentration and holding temperature: white plots are literature data [13, 14].