Synthesis and mechanical properties of (Mo0.94Nb0.06)(Si0.97Al0.03)2−x vol% SiC composites fabricated via SHS-HP

(Mo0.94Nb0.06)(Si0.97Al0.03)2-SiC composites were consolidated via vacuum HP sintering from the mixture of (Mo0.94Nb0.06)(Si0.97Al0.03)2 powder and SiC nanoparticles. The (Mo0.94Nb0.06)(Si0.97Al0.03)2 powder was prepared by self propagating synthesis (SHS). The effects of SiC content on the ambient temperature mechanical properties and microstructure of the SHS-HP composites were investigated. The results show that the indentation fracture toughness, bending strength and Vickers hardness of (Mo0.94Nb0.06)(Si0.97Al0.03)2−x vol% SiC composites increase gradually with the increase of SiC content. The grain size and relative density of the composites decrease gradually with increase of SiC content. (Mo0.94Nb0.06)(Si0.97Al0.03)2−15 vol% SiC composite exhibits excellent mechanical properties: Vickers hardness 12.62 GPa, fracture toughness 5.01 MPa m1/2, bending strength 472 MPa. With the addition of SiC, the fracture mode transforms from a mixed mode of transcrystalline and intercrystalline fracture to mainly transcrystalline fracture.