In this study, 0.75, 1.5, 2.5, 3.5, and 5 vol.% of alumina nanoparticles were incorporated into the A356 aluminum alloy by a mechanical stirrer and then, cylindrical specimens were cast at 800°C and 900°C. A uniform distribution of reinforcement, grain refinement of aluminum matrix, and presence of the minimal porosity was observed by microstructural characterization of the composite samples. Characterization of mechanical properties revealed that the presence of nanoparticles significantly increased compressive and tensile flow stress at both casting temperatures. The highest compressive flow stress was obtained by 2.5 vol.% of Al2O3 nanoparticles. It is then observed that the flow stress decreases when Al2O3 concentration increased further to 5 vol.% irrespective of the amount of deformation and casting temperature. It was revealed that the presence of nano-Al2O3 reinforcement led to significant improvement in 0.2% yield strength and ultimate tensile stress while the ductility of the aluminum matrix is retained. Fractography examination showed relatively ductile fracture in tensile-fractured samples.

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Applying aluminum composite in the defense, aerospace and automotive industries depends on how they behave during the elasto-plastic form change. In addition to the factors responsible for changing the form of the alloy, many other factors have an impact on the behavior of the composite form change. In this study, the effect of casting type on the mechanical properties of Al-Si nano composites has been investigated. Due to the proper distribution of reinforcing particles, tensile strength in compo casting sample in semi-solid state is higher than sand casting and squeeze casting. In all samples, the tensile strength of the heat-treated samples has increased by about 30%. Tensile strength in compo casting sample in semi-solid state was obtained with higher nano particle reinforcing particles, which can be explained by the fact that the percentage of elongation in micro samples was lower than that of nano composite samples.