Synthesis of nanocrystalline MoSi2 by mechanical alloying

In this investigation, the Mo33Si66 intermetallic compound has been synthesized from the elemental powders by mechanical alloying (MA) and heat treatment of mechanically alloyed powders. In order to study the structural evolutions, the X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used. Results show that α-MoSi2 is obtained after 30 h of milling. Increasing the milling time up to 150 h leads to the formation of α-MoSi2 with 12 nm crystallite size. The synthesis of α-MoSi2 is due to the reaction which takes place in a combustion mode, but does not propagate completely. The annealing of 10-h milled powders at 1000 °C results in the formation of a trace amount of α-MoSi2. On the other hand, during the annealing of 30-h milled powders, residual Mo and Si react and form a considerable amount of α-MoSi2; meanwhile, the crystallite size of α-MoSi2 grows obviously.