Fabrication and study on mechanical properties and fracture behavior of nanometric Al2O3 particle-reinforced A356 composites focusing on the parameters of vortex method

In the present study, a novel approach was used focusing on nanoparticle distribution in aluminum matrix. To manufacture A356/1.5 vol.% nano-Al2O3 reinforced composite, nano-Al2O3 particles were separately milled with aluminum and copper powders and incorporated into A356 alloy via stir casting method. The effects of adding different mixed powders to the matrix and parameters of stirring process on the mechanical properties of the composites were investigated by hardness and tensile tests. Based on the results, it was revealed that the presence of nano-Al2O3 particles in aluminum matrix led to a significant improvement in the mechanical properties of the composites compared with those of the aluminum alloy. This enhancement in mechanical properties can be attributed to the effect of nanoparticles on grain refinement and strengthening of the aluminum matrix. Also, an increase in stirring time led to a decrease in mechanical properties of the composites. These variations in mechanical properties can be attributed to the variation of porosity content versus stirring time. The microstructural characterization of the composites showed the uniform distribution of nanoparticles and grain refinement of matrix. Studies on fracture surfaces revealed that the failure of matrix was the basic mechanism of fracture in this composite.