Microstructure and High-Temperature Strength of Directionally Solidified Al₂O₃/YAG/ZrO₂ Eutectic Composite

The microstructures of an A₂O₃/YAG/ZrO₂ eutectic Melt-Growth-Composite (MGC) solidified unidirectionally by the modified-pulling-down method were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and electron backscattered pattern (EBSP) method. The anisotropy of strength was investigated by hardness tests and compression tests at various directions of the composite at elevated temperatures. The eutectic MGC has strong preferred growing orientation and the constituent phases hold the orientation relationship. The eutectic MGC shows excellent high-temperature strength and can deform plastically above about 1500 K. High-temperature strength above 1500 K depends on strain rate, temperature and orientation.