Phase evaluation during high temperature long heat treatments in the Y2O3–Al2O3–SiO2 system

The effect of high temperature long heat treatments on the microstructure of the eutectic glass composition in the Y2O3–Al2O3–SiO2 system was examined. The qualitative and quantitative phase analyses were conducted by using scanning electron microscopy combined with energy dispersive analysis and electron microprobe. Simultaneous thermal analyses were carried out to determine the transition temperatures and enthalpies. The crystallization behavior of these glasses was monitored with X-ray powder diffraction. A needle like X-phase was observed in the structure of this eutectic composition after long heat treatment at 1350 °C.