Abstract
Fine MoSi2 powder and MoSi2-10wt%SiC composite powder (particle size: ca. 1μm) prepared by a carbothermal reduction process were hot-pressed at 1600-1900°C to investigate the microstructure and mechanical properties of the sintered bodies. The sintered density of synthesized MoSi2 powder reached 97% of theoretical at 1700°C but decreased at a higher temperature. MoSiZ SiC composite powder re-quired a high temperature of 1800°C for densification. Commercial MoSi2 powder (particle size: 6-12μm) was densified to 99% at a low temperature of 1600°C. The low sinterabilities of the synthesized powders were caused by the formation of closed pores with grain growth. Although the sintered bodies of the commercial powder had the high density, the hardness and fracture toughness were low. On the other hand, the sintered bodies of the synthesized powders had high hardness and fracture toughness owing to the fine microstructures. The hardness and fracture toughness were further improved by SiC inclusions.
