Microstructures and Fracture Behaviors at High Temperatures for A12O3-Sic Nanocomposites

Abstract

Effects of nano-size SiC dispersions on the microstructures and mechanical properties have been investigated for Al2O3 nanocomposites. These Al2O3 nanocomposites were prepared by hot-pressing the mixtures of fine Al2O3 and SiC powders. Transmission electron microscopic observations indicated the fine SiC particulate less than 0.2 μm were uniformly dispersed predominantly within Al2O3 matrix grains. The significant increase of mechanical properties were achieved for Al2O3/SiC nanocomposites, comparable to Si3N4 and SiC. In special, the fracture strength of Al2O3 was approximately 3 times increased by the SiC dispersions. Another interesting finding is that the high temperature mechanical properties were effectively improved by dispersing the second phase on nanometer. The rolls of the nanometer-size second phase on the microstructure and fracture behaviors at high temperatures will be discussed.