Abstract
MoSi2 is one of the-most promising candidate for high-temperature structural materials because of its high melting points and excellent oxidation resistance. However, the low room temperature fracture toughness and ductility, etc. of MoSi2 still remains as major obstacles to potential high temperature structural applications. The fracture toughness of brittle matrix can be improved by the incorporation of a ductile second phase such as metallic Nb. The purpose of this study is to improve the room temperature fracture toughness and ductility of sintered MoSi2 and MoSi2/Nb composites respectively by densification, refining of microstructure and minimizing of interfacial reactions between matrix and Nb. These compound and composite are prepared by mechanical alloying(MA)-spark plasma sintering(SPS) process. The microstructures and material properties of these samples were investigated by optical microscopy, SEM, XRD, EPMA, microhardness measurement and 4-point bending test. The Vickers hardness, bending strength and fracture toughness increased with the incorporation of metallic Nb.
