Hardness and Tensile Strength Study on Al356 Alloy Matrix-nano Al2o3 Particle Reiforced Composite

Additions of high modulus nano particles to Aluminum alloys offer the potential to develop a lightweight composite with high mechanical properties. It is extremely difficult to disperse nano-sized ceramic particles uniformly in molten metal. In order to investigate the effect of nano-alumina on the microstructure and mechanical properties of composite, a new method was used in stir casting to avoid agglomeration and segregation of particles. Then, cylindrical specimens with different volume fractions of nano-alumina at different temperatures were cast and tested. The microstructure of the composites was investigated by scanning electron microscopy (SEM). Experimental results show a nearly uniform distribution and good dispersion of the nano-particles within the Al matrix, although some of small agglomeration was found in matrix. The effects of Al2O3 particle content and casting temperature on the hardness and tensile strength of the composites were investigated. Based on experiments, both hardness and tensile strength was enhanced by incorporation of nano-alumina into matrix. The enhancement in values of hardness and tensile strength observed in this experiment is due to small particle size and good distribution of the Al2O3 particles, which was confirmed by SEM pictures.