Synthesis of nanostructured Al-Mg-SiO2 metal matrix composites using high-energy ball milling and spark plasma sintering

► High-energy ball milling process has been successfully employed to synthesize Al-x%Mg-5 wt% SiO2 (x = 0.5, 1, 2.5, 5) nanocomposites. ► Increase in the amount of Mg in the composite powder results in a finer crystallite size. ► The hardness of nanocomposites is more than twice as high as that of microcomposite. ► Increase in hardness is attributed to (a) formation of hard phase MgAl2O4 spinel along with Al2O3 and (b) finer crystallite size obtained by SPS process.