Synthesis of MoSi2 powder by mechanical alloying

Systematic investigations were carried out on the synthesis of MoSi2 powders by using a combination of mechanical alloying (MA) and vacuum heat treatment techniques. MA was conducted by two different high-energy ball mills under various milling conditions. The mechanically alloyed powders were characterized by X-ray diffraction and scanning electron microscopy as well as differential scanning calorimetry. The results showed that the preparation of MoSi2 phase is not successful for all the mechanically alloyed powders after being milled with a less energetic planetary ball mill. However, the low-temperature α-MoSi2 phase and the high-temperature β-MoSi2 phase were formed when the same powder mixtures were mechanically alloyed with a more energetic shaker ball mill after a long milling time. Microstructural investigation indicates that cold welding behavior of Mo and Si powders during MA treatment has a pronounced effect on the formation of MoSi2 phases. Vacuum heat treatment can also promote the formation of MoSi2 phases in mechanically alloyed powders which are processed with shaker ball mill.