246 Research on SiC_P/MoSi₂ Composites Prepared by in — Situ Reaction Attached Hot — Pressing Synthesis

MoSi₂ composites with different volume fraction of SiC particles were prepared by the technology of in—situ reaction attached hot—pressing the pure powder of Mo, Si and C in argon atmosphere after alcohol mixing. The effects of in—situ formed SiC particles on the flexural strength, fracture toughness and microstructure of SiC_P/MoSi₂ composites were studied. The research shows SiC_P/MoSi₂ composites can be fabricated by in—situ reaction attached hot—pressing technology. In addition, the relative density, flexural strength and fracture toughness of the composites are increased compared with those of the pure MoSi₂ material. It is found that the in—situ formed SiC particles refine the MoSi₂ grains and eliminate the brittle SiO₂ glass phase. The increase of the flexural strength and fracture toughness of SiC_P/MoSi₂ composites is mainly attributed to the refinement of MoSi2 grains, dispersion strengthening of the in—situ formed SiC particles and elimination of the brittle SiO₂ glass phase.