Reactive Infiltration of Si-Mo Alloyed Melt into Carbonaceous Preforms of Silicon Carbide

A MoSi₂/reaction-bonded SiC composite was prepared from a preform of petroleum coke and commercial SiC powders (in weight ratios of 0.5 and 0.6), following reactive infiltration of a Si-Mo melt (molybdenum concentration of 7–29 wt%) made from elemental powder. The resulting material had a relative density of >90% of the theoretical density and, on a microstructural scale, contained SiC and MoSi₂, in addition to unreacted carbon and silicon. The SiC and MoSi₂ boundary was smooth and sharp, with no sign of any reaction. The occasional presence of an intermediate zone between SiC and MoSi₂ was detected; this zone contained silicon, iron, and aluminum, the formation of which may be related to the presence of impurities in the silicon and SiC.