Phase composition and mechanical properties of in-situ synthetic Mo-Si compound composites

Mo-Si compound composites were in situ fabricated by means of reactive hot-pressing using Mo powder and Si powder as raw materials. Their phase composition and mechanical properties were investigated for the design and fabrication of Mo-Si functionally gradient material with high-temperature anti-oxidation properties in future. The results indicate that the reaction products in Mo-Si system vary in the order of MoSi₂-Mo₅Si₃-Mo₃Si with the increase of Mo content in the mixed powders. The hardness and the elastic modulus of in-situ synthetic Mo-Si compound composites are mainly controlled by their porosity. The maximum hardness of Mo₅Si₃-MoSi₂ composites with very fine dispersive microstructure reaches to 12.88 GPa. The Mo-Si compound composites show macro-brittleness and the same varying tendency in flexural strength and fracture toughness with the change of Mo content. In Mo-Si compound composites, the MoSi₂-Mo₅Si₃ composite exhibits good combined mechanical properties.