Phase compositions and microstructural characteristics of solidified Al2O3-rich spinel solid solution/YAG composite

The phase compositions and microstructures of an Al2O3-rich spinel solid solution (MAss)–YAG composite were investigated by conventional solidification. A binary eutectic system of YAG–MAss exhibiting changed eutectic temperature was proven to exist in the YAG–spinel–alumina ternary phase region. A YAG–MAss eutectic-like composite was obtained by controlled cooling process. It was found that metastable phase, YAlO3, was formed during rapid solidification of the YAG–MAss composite from an annealing temperature of 1795°C. When reheating the as-solidified YAlO3–MAss composite at 1500°C, a YAG–MAss composite with fine-grained YAG phase was obtained.