Influence of alumina and zinc oxide nanoparticles on microstructure and electro-mechanical properties of aluminum metal matrix composites fabricated by customized two-step stir casting method

The present paper reports the influence of Alumina (Al2O3) and Zinc Oxide (ZnO) nanoparticles on the microstructure and electro-mechanical properties of aluminum metal matrix composites (Al MMCs) fabricated by a customized two-step stir casting method. Two types of Al MMCs were developed, (i) Al MMC-01 having 97.5 wt. % of Al and 2.5 wt. % of Al2O3 and (ii) Al MMC-02 having 95 wt. % of Al, 2.5 wt. % of Al2O3 and 2.5 wt. % of ZnO. The microstructures of Al MMC-1 and Al MMC-2 observed in a Scanning electron microscope (SEM) have affirmed the uniform distribution of Al2O3 and ZnO in the metal matrix composites. It has been observed that the addition of 2.5% Al2O3 has improved the hardness, flexural strength, and impact toughness of Al composite significantly compared with pure Al. Furthermore, both bulk and micro hardness of Al MMC-02 have also increased significantly. However, impact strength, flexural strength, modulus of elasticity, and electrical conductivity of Al MMC-02 have been reduced by 12%, 52.5%, 60.8%, and 9.81% respectively in comparison with Al MMC-01 as it becomes brittle in nature for the presence of cleavage cracks, deep shear dimples, and crystallographic planes than that of Al MMC-01 as revealed by fractured surface analysis through SEM.