Rapid synthesis of Mo 5Si 3-Al 2O 3 nanocomposite powders by mechanochemical reduction method

Abstract

Mo 5Si 3–20%Al 2O 3 (mass fraction) nanocomposite was synthesized by mechanical alloying (MA) of mixture of MoO 3, Mo, Si and Al powders. The structural evolutions of powder particles during mechanical alloying were studied by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential thermal analysis (DTA). Results show that Mo 5Si 3–20%Al 2O 3 was obtained after 10 h of milling. The spontaneous reaction of powders takes place in an explosive mode. The crystallite sizes of Mo 5Si 3 and Al 2O 3 after milling for 30 h were 36.3 nm and 21.9 nm, respectively. With longer milling time, the intensities of Mo 5Si 3 and Al 2O 3 peaks decreased and became broad due to the decrease in crystallite size. Thermal analysis results and XRD analysis results show that the Mo 5Si 3-Al 2O 3 nanocomposite powders are very stable during milling (up to 30 h) and heating (up to 1 000 °C) and no transformation takes place.