Microstructures and Room Temperature Mechanical Properties of Mo-12Si-8.5B-8Cr Alloy

Microstructures and room temperature mechanical properties of Mo-12Si-8.5B and Mo-12Si-8.5B-8Cr alloys were investigated. The alloys, which were prepared by spark plasma sintering at various temperatures, were analyzed using scanning electron microscopy, x-ray diffraction, vicker hardness test, and three-point bending test. Moss matrix with uniformly distributed intermetallic phases of Mo3Si and Mo5SiB2 were observed in the microstructures of both Mo-12Si-8.5B and Mo-12Si-8.5B-8Cr alloys. The solution of Cr in solid phases of Mo, Mo3Si and Mo5SiB2 phases was detected. Hardness and room temperature flexure strength of two alloys increased with the increase in sintering temperature. Under the same sintering conditions, the addition of Cr obviously decreased the porosity of Mo-12Si-8.5B sintered body, and significantly increased the hardness, room temperature flexure strength and fracture toughness.