Preparation of FeAl–Al2O3 nanocomposite via mechanical alloying and subsequent annealing

Abstract

FeAl–Al2O3 nanocomposite was successfully synthesised via milling of Fe2O3 and Al powders mixture at nominal room temperature. Effects of the milling time and annealing were investigated. X-ray diffraction and transmission electron microscopy were used to characterise the structure of the milled and annealed powders. The morphological evolutions were studied by scanning electron microscopy. Results showed that two mechanically induced self-sustaining reactions took place, simultaneously to form a product of nanocrystalline mixture of Al2O3 and FeAl powders. This nanocomposite was also synthesised during annealing of the milled powder at 1000°C. Mean grain sizes of 28 and 24 nm were obtained for FeAl and Al2O3 after annealing of the 360 min milled powders at 1000°C respectively. Maximum microhardness of 11 GPa was procured at the end of milling (3000 min). Scanning electron microscopy images showed very fine particles with the mean size of 30 μm at the end of milling.