Combustion synthesis of MoSi₂-Mo₅Si₃ composites

Thermochemical calculations were carried out for the Self-propagating High-temperature Synthesis (SHS) of MoSi₂, Mo₅Si₃, and their composites. Adiabatic temperatures and the amounts of liquid phases formed at the adiabatic temperature were calculated for different initial temperatures. These materials were prepared from elemental powders of Mo and Si by the thermal explosion mode of SHS. The products were characterized by x-ray diffraction, scanning electron microscopy, and microhardness. The larger particle morphology of MoSi₂ and the MoSi₂-Mo₅Si₃ composite and the finer morphology of Mo₅Si₃ can be explained in terms of the presence of transient liquid phase at the adiabatic temperature. The morphology of fracture surface of MoSi₂ shows intergranular fracture, while Mo₅Si₃ and the MoSi₂-Mo₅Si₃ composite show transgranular cleavage fracture.