A comparison of MoSi2 matrix composites with other silicon-base composite systems

Molybdenum disilicide offers the potential of enhancing the mechanical properties of silicon-base composite structural materials. This material can be alloyed with other ceramics, e.g. Si3N4, to increase the cracking strength, toughness, and oxidation resistance. Matrix toughness is shown to have a significant influence on increasing the matrix cracking stress and is one of the few material variables that can be controlled. The uniaxial stress-strain behavior of MoSi2–Si3N4 matrix composites reinforced with SCS-6 fibers demonstrates a high load carrying capacity at high strains. The overall toughness can also be significantly enhanced, particularly at high temperatures. These results suggest that the alloying capabilities of MoSi2 matrix systems will provide the flexibility needed to achieve further improvements in material performance for silicon-base composites.