Synthesis of MoSi 2–Al 2O 3 nanocomposite by mechanical alloying

Abstract

MoSi 2–Al 2O 3 nanocomposite was synthesized by mechanical alloying (MA) of MoO 3, SiO 2 and Al powder mixture. The structural evolution of the powders was studied by X-ray diffraction (XRD). Both β-MoSi 2 and α-MoSi 2 were obtained after 3 h of milling. The spontaneous formation of β-MoSi 2 during milling proceeded by a mechanically induced self propagating reaction (MSR), analogous to that of the self propagating high temperature synthesis (SHS). After 70 h of milling the β-phase transformed to α-phase. The crystallite size of α-MoSi 2 and Al 2O 3 after milling for 100 h was 12 and 17 nm, respectively. Residual Mo and Si in the 3 and 70 h milled samples formed β-MoSi 2 and Mo 5Si 3 during heating at 1000 °C, respectively.