Influence of powder composition and milling media on the formation of molybdenum disilicide by a mechanically induced self-propagating reaction

The spontaneous formation of molybdenum disilicide (α-MoSi₂) during the mechanical alloying of a stoichiometric Mo-Si powder mixture occurred by a mechanically induced self-propagating reaction (MSR) - a mechanism similar to that of the thermally ignited self-propagating high-temperature synthesis (SHS). The bulk of α-MoSi₂ formation occurred in less than 15 min once the reaction commenced after 14 h, 15 min of milling. When the milling media was switched from zirconia to steel, however, the reaction rate became sluggish as both the α and β phases were formed. The mechanical alloying of the Si-rich and Si-poor compositions was also characterized by the gradual formation of α and β phases.