High-temperature strength and a microstructure of an Al2O3/Er3Al5O12/ZrO2 ternary MGC

Al2O3/EAG/ZrO2 ternary MGCs (Melt Growth Composites) with a new microstructure have been fabricated by unidirectional solidification. The superior high-temperature strength of Al2O3/EAG/ZrO2 ternary MGCs over Al2O3/EAG binary MGCs was obtained by the following means: a new combination of single-crystal Al2O3, with a hexagonal structure, single-crystal EAG with a garnet structure and Zr0.8Er0.2O1.9 phases with a cubic structure; a microstructure consisting of three-dimensionally continuous and complexly entangled single-crystal Al2O3, single-crystal YAG and Zr0.8Er0.2O1.9 phases: characteristic dimension of the microstructure around 2 similar to4 mum (this dimension is defined as the typical length of the short axis of each domain seen in the cross-section perpendicular to the solidification direction) for EAG phases, around 2 similar to4 mum for Al2O3 phases reinforced with around 0.4 similar to0.8 mum Zr0.8Er0.2O1.9 phases. These features are finer than that for the Al2O3/EAG binary MGC. No amorphous phases are formed at interfaces between phases in the ternary MGC.