Combustion synthesis and mechanical properties of molybdenum disilicide composites reinforced with SiC particulate

Intermetallic composites of molybdenum disilicide reinforced with silicon carbide were produced by combustion synthesis of the elemental powders. The combustion reaction was initiated near 700°C and completed within a few seconds. The end product was a porous composite which was subsequently hot pressed to >97% theoretical density. The grains of the matrix were 8–14 μm in size surrounded by SiC particulate reinforcement of 1–5 μm. The mechanical properties of the composites improved with increasing SiC reinforcement. The hardness of the materials increased from 10.1 GPa to 12.7 GPa with the addition of 20 vol% SiC reinforcement, while the strength increased from 195 MPa to 299 MPa. The fracture toughness also increased from 2.79 MPa m1/2 to 4.08 MPa m1/2 with 20 vol% SiC. © 1998 Chapman & Hall