Rapid synthesis of MoSi 2 -Si 3 N 4 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 diferent products such asα-andβ-MoSi2,Si3N4,Mo2N,and Mo5Si3at various milling times.A thermodynamic appraisal showed that the milling of Mo32Si68powder 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 ofα-MoSi2and the reaction between Si and N2to produce Si3N4under a nitrogen pressure of 1 MPa.By increasing the nitrogen pressure to 5 MPa,more heat is released,resulting in the dissociation of Si3N4and the transformation ofα-MoSi2toβ-MoSi2.Heat treatment was also performed on the milled samples and led to the formation of Mo2N and the transformation ofα-MoSi2toβ-MoSi2at the milling times of 10 and 40 h,respectively.