Influence of microstructural size on the thermal shock behavior of Al2O3-Er3Al5O12 directionally solidified eutectics

Abstract

We analyze the thermal shock resistance of directionally solidified eutectics. When quenching in water, the resistance starts to deteriorate with temperature differences in the range 260 to 300 K, almost independent of the microstructure size (or initial flexural strength). Unlike other strong, dense ceramics, the loss of strength is gradual upon quenching in boiling water. The onset of crack propagation seems to be controlled by the mismatch of the thermal and elastic properties of the component phases, while the length of the propagated cracks is limited by their quantity, which is estimated to scale approximately with the interface density.