Rapid synthesis of MoSi₂-Si₃N₄ nanocomposite via reaction milling of Si and Mo powder mixture

The nanocomposite of MoSi₂-Si₃N₄ (molybdenum disilicide-silicon nitride) was synthesized by reaction milling of the Mo and Si powder mixture. Changing the processing parameters led to the formation of different products such as α- and β-MoSi₂, Si₃N₄, Mo₂N, and Mo₅Si₃ at various milling times. A thermodynamic appraisal showed that the milling of Mo₃₂Si₆₈ powder mixture was associated with highly exothermic mechanically induced self-sustaining reaction (MSR) between Mo and Si. The MSR took place around 5 h of milling led to the formation of α-MoSi₂ and the reaction between Si and N₂ to produce Si₃N₄ under a nitrogen pressure of 1 MPa. By increasing the nitrogen pressure to 5 MPa, more heat is released, resulting in the dissociation of Si₃N₄ and the transformation of α-MoSi₂ to β-MoSi₂. Heat treatment was also performed on the milled samples and led to the formation of Mo₂N and the transformation of α-MoSi₂ to β-MoSi₂ at the milling times of 10 and 40 h, respectively.