Formation mechanism and nanocrystalline phase transformation of molybdenum disilicide by mechanical alloying

The formation mechanism of stoichiometric MoSi2 by mechanical alloying (MA) from elemental powders has been investigated. The experimental results demonstrate that molybdenum disilicide can be synthesized by MA through different formation mechanisms, which are governed by the milling energy. MoSi2 is formed by the mechanism of self-propagating high-temperature synthesis (SHS) at high rotational speeds and most likely by the mechanism of a mechanical collision reaction (MCR) at lower rotational speeds. Nanocrystalline phase transformation of alpha --> beta occurs during MA when the crystallite size decreases to approximately 8 nm; the final product of MA IS beta-MoSi2.