Abstract
This paper presents a selection of the eutectic systems in the Al2O3–Y2O3–ZrO2 pseudo-ternary system and the production of the undercooled melt due to melting of the metastable eutectic structure at the metastable eutectic temperature. In the pseudo-ternary system, there are two eutectic systems; one is the Al2O3–YAG(Y3Al5O12)–ZrO2 equilibrium system and the other is the Al2O3–YAP(YAlO3)–ZrO2 metastable system. The eutectic system was selected by maximum melt temperature before solidification. YAG nucleation was inhibited in the melt when heated above 2250 K and consequently the metastable eutectic solidification path was selected. The selection controlled by the melt temperature before solidification was similar to that of the Al2O3–Y2O3 system. Furthermore, the undercooled melt formation was found when the Al2O3–YAP-ZrO2 metastable eutectic structure was heated up to temperatures above the metastable eutectic temperature. The addition of ZrO2 to the Al2O3–Y2O3 system inhibited the YAG nucleation remarkably and enhanced the undercooled melt formation in comparison with the Al2O3–Y2O3 pseudo-binary system. Ease of the undercooled melt formation in the pseudo-ternary system will be beneficial for the melt shaping processes.
