In situ synthesis of FeSi-Al2O3 nanocomposite powder by mechanical alloying

FeSi-Al2O3 nanocomposite powder was successfully synthesized via mechanical alloying of SiO2 and Al powders in stainless steel cup and balls. Effects of the Al morphology, milling time and annealing temperature were investigated. Structural and morphological evolutions were monitored by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Results show that the reduction of TiO2 by spherical Al initiates after 30 h and completes after 45 h of milling. However, there is no reaction with flaky Al up to 45 h of milling. The mean grain size of 9 nm was obtained for FeSi at the end of milling. FeSi-Al2O3 nanocomposite powder was stable and maintained its nanocrystalline nature after annealing at 1000 °C. Combination of mechanical activation and heat treatment led to the formation of Fe0.42Si2.67 and mullite phases in the 10 h milled sample.