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 μm for EAG phases, around 2–4 μm for Al2O3 phases reinforced with around 0.4–0.8 μm 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. C 2005 Springer Science + Business Media, Inc.