INFLUENCE OF POWDER COMPOSITION AND MILLING MEDIA ON THE FORMATION OFMOLYBDENUM DISILICIDE BY A MECHANICALLY INDUCED SELF-PROPAGATING REACTION

The spontaneous formation of molybdenum disilicide (alpha-MoSi2) durin g the mechanical alloying of a stoichiometric Mo-Si powder mixture occ urred by a mechanically induced self-propagating reaction (MSR)-a mech anism similar to that of the thermally ignited self-propagating high-t emperature synthesis (SHS). The bulk of alpha-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 alpha and beta phases were formed, The mechanical alloying of the Si-rich and Si-poor compositions was also characterized by the gradual formation of alpha and beta phases.