Abstract:Mo₅Si₃-20%Al₂O₃ (mass fraction) nanocomposite was synthesized by mechanical alloying (MA) of mixture of MoO₃, 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 Mo₅Si₃-20%Al₂O₃ was obtained after 10 h of milling. The spontaneous reaction of powders takes place in an explosive mode. The crystallite sizes of Mo₅Si₃ and Al₂O₃ after milling for 30 h were 36.3 nm and 21.9 nm, respectively. With longer milling time, the intensities of Mo₅Si₃ and Al₂O₃ peaks decreased and became broad due to the decrease in crystallite size. Thermal analysis results and XRD analysis results show that the Mo₅Si₃-Al₂O₃ nanocomposite powders are very stable during milling (up to 30 h) and heating (up to 1 000 °C) and no transformation takes place.

Key words: Mo₅Si₃-Al₂O₃; nanocrystalline; mechanical alloying; intermetallic