Characterization of Al2O3 in Fe3Al-30 vol.% Al2O3 nanocomposite powder synthesized by mechanochemical process

During the last decade, mechanochemical synthesis, which can provide the nanostructured constituents, has been considered as an alternative technique to the conventional thermite reactions to produce the metallic-ceramic composite. Detection of the reinforcement in such nanocomposite powders has been provided challenges as a result of low volume fraction and high induced lattice strain. In this work, the mechanochemical reaction of a non-stoichiometry Fe2O3-Al system (Fe2O3+Al+Fe powder mixture) was performed to produce the Fe3Al-30 vol.% Al2O3 nanocomposite. The progress of the reaction was followed by X-ray diffractometry (XRD) and transmission electron microscopy (TEM). XRD analysis of mechanochemically synthesized Fe3Al-30 vol.% Al2O3 nanocomposite showed no evidence of the produced Al2O3 phase, whereas TEM analysis revealed the crystalline Al2O3 phase. The X-ray absorption by component higher mass absorption coefficient (Fe3Al matrix) in highly strained nanocomposite leads to a decrease in the diffraction intensity of components with lower mass absorption coefficient and with low volume fraction (Al2O3). High-temperature heat treatment lead to crystallite growth as well as lattice strain reducing, which resulted in the capability of detection of Al2O3 by XRD analysis.