High-temperature mechanical properties of SiC-Mo sub 5 (Si,Al) sub 3 C composites

SiC-Mo sub 5 (Si,Al) sub 3 C composites were fabricated by the melt infiltration process, and the infiltration characteristics were studied in detail. Fracture strength and toughness were measured up to 1600 deg C using a three-point bending test and indentation strength method, respectively. Both fracture strength and toughness significantly increased at 1400 deg C with respect to the values at room temperatures. These increases were mainly attributed to plastic deformation of the infiltrated MO sub 5 (Si,Al) sub 3 C phases at elevated temperatures, which acted as ductile toughening inclusions. Compressive creep test were used to study the creep behavior of the composite in the range of 1550-1650 deg C and 150-200 MPa. The stress exponent and activation energy were 1.3 and 277 kJ/mol, respectively. Preliminary oxidation tests showed that the composites exhibited good oxidation resistance at 1500 deg C because of the formation of a dense oxide scale.