Directionally-Solidified Eutectic Oxide Ceramics

Directionally-solidified eutectic ceramic oxides are a family of in situ composite materials with a homogeneous and stable microstructure, whose morphology and size can be tailored by processing. Their hardness and strength at ambient temperature are comparable to or even better than those obtained in conventional structural ceramics. Additionally, due to the presence of large amounts of clean, strong interfaces and to the homogeneity of the microstructure, DSE maintains the mechanical properties up to temperatures very close to the eutectic point even in oxidizing environments. As compared with other ceramic oxides, DSE oxides show good thermal shock resistance and fracture toughness, although they do not attain the outstanding values measured in some carbides and borides. This article briefly reviews these DSE oxides and also some spinel-(MgAl 2 O 4 ) and ZrO 2 -based eutectics under the light of recent developments. The emphasis is on the relationships between growth parameters and microstructure, hence on the influence of the microstructure in the mechanical properties of these compounds