Microstructure and high-temperature strength of Al2O3/Er3Al5O12/ZrO2 ternary melt growth composite

A new Al2O3/Er3Al5O12(EAG)/ZrO2 ternary MGC (Melt Growth Composite) with a novel microstructure has been fabricated by unidirectional solidification. This ternary MGC has a microstructure consisting of continuous networks of single-crystal Al2O3, single-crystal EAG and fine cubic-ZrO2 phases without grain boundaries. The ternary MGC has also characteristic dimensions of the microstructure of around 2–4 μ m for EAG phases, around 2–4 μ m for Al2O3 phases reinforced with around 0.4–0.8 μ m cubic-ZrO2 phases. No amorphous phases are formed at interfaces between phases in the ternary MGC. The ternary MGC’s flexural strength at 1873 K is approximately 700 MPa, more than twice the 330 MPa of the Al2O3/EAG binary MGC. The fracture manner of the Al2O3/EAG/ZrO2 ternary MGC at 1873 K shows the same intergranular fracture as the Al2O3/EAG binary MGC, but is significantly different from the transgranular fracture of the sintered ceramic.