In-situ fabrication of Al3V/Al2O3 nanocomposite through mechanochemical synthesis and evaluation of its mechanism

In this research, in situ fabrication of Al3V based nanocomposite and its formation mechanism have been investigated. In order to synthesize Al3V/Al2O3 nanocomposite, a mixture of Al and V2O5 powders was subjected to high-energy ball milling and the nanocomposite was produced through a mechanochemical reaction. The produced structure was isothermally heat-treated at 500–600 °C for 0.5–2 h under argon atmosphere. In order to evaluate the structural changes during milling and annealing, the synthesized powders were characterized by X-ray diffraction (XRD). Moreover, the powder morphological changes were studied by scanning electron microscopy (SEM). It was observed that the reaction between Al and V2O5 occurred after about 30 min and, the Al3V and Al2O3 were formed in nanocrystalline structure with the continuing mechanical milling. Calculation of adiabatic temperature confirmed that reaction took place in combustion mode. In final stage of milling up to 40 h; it was observed that the Al3V decomposed to Al and V so that the optimum time of milling to achieve fabrication of nanocomposite was determined to be about 20 h. Calculations based on Miedema’s model verified partial disordering of Al3V during further milling and annealing of as-milled powder at 600 °C led to the ordering of Al3V. The crystallite size of Al3V and Al2O3 after annealing at 600 °C for 2 h remained in nanometer scale. So the final product appeared to be stable even after annealing.

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► Mechanochemical reaction between Al and V2O5 took place in combustion mode after about 30 min of milling.
► Determination of Adiabatic temperature and measurement of vial temperature was indicated that the mechanochemical reaction was performed in combustion mode.
► As-fused shape of particles confirmed the occurrence of combustion synthesis.
► Appearance of a number of supperlattice peaks in the XRD patterns indicating the occurrence of an order-disorder transformation in Al3V during annealing.