ZrO sub 2 and ZrO sub 2 --SiC Particle Reinforced MoSi sub 2 Matrix Composites

ZrO sub 2 --MoSi sub 2 and (ZrO sub 2 --SiC)--MoSi sub 2 composites were fabricated by hot pressing and hot pressing--hot isostatic pressing at 1700 deg C. No reactions between ZrO sub 2 , SiC and MoSi sub 2 were observed. An amorphous silica glassy phase was present in all composites. Composites with unstabilized ZrO sub 2 particles exhibited the highest room temperature toughness and 1200 deg C strength of (ZrO sub 2 --SiC)--MoSi sub 2 composites were higher than those of ZrO sub 2 --MoSi sub 2 composites, indicating beneficial effects of combined reinforcement phases. Low strength levels were observed at 1400 deg C as a result of the presence of the silica glass phase. Elimination of glassy phases and refinements in microstructural homogeneity are processing routes important to the optimization of the mechanical properties of these types of composites.