Correlation between energy transfers and solid state reactions induced by mechanical alloying on the Mo₃₃Si₆₆system

Phase transformations of the Mo₃₃Si₆₆powder mixture under different milling conditions have been systematically investigated by x-ray diffraction, and scanning and transmission electron microscopy. The effect of the milling conditions on the Mo/Si solid state reactions (SSR) has been examined in detail. The energy transfer from the milling tools to the powder under processing has been quantified by an already assessed collision model. It has been found that the higher energetic input favors the formation of the room temperature stable phase αMoSi₂, while the lower energetic input promotes the formation of the metastable phase βMoSi₂. In addition, if the energy transfer is high enough, the Mo/Si reaction proceeds in a form of self-propagating high temperature synthesis (SHS). Thermodynamics and kinetics aspects related to the different SSR's are discussed.