Influence of Hybrid Reinforcement on Microstructure and Mechanical Properties of Magnesium Alloy Nanocomposites: A Study

In this paper, the results of a recent study on magnesium alloy (AZ91) reinforced with 1.5% (weight percent) of alumina (Al2O3) and 0.5% (weight percent) of ZrO2 (zirconium dioxide) nanoparticles (less than 50 nm) are highlighted and discussed. The magnesium alloy nanocomposites were developed using the stir casting technique and under the protection of flux material. When compared with the monolithic magnesium alloy, microstructural characterization of the engineered nanocomposites revealed a near uniform dispersion of the fine nanoparticles through the magnesium alloy metal matrix coupled with an observable reduction in grain size. Addition of nanoparticles contributed to enhancing both the microhardness and ductility of the engineered composites. Both scanning electron microscopy observations and X-ray diffraction analysis were used to systematically characterize the microstructural intricacies of the as-prepared composites. A contribution of the two chosen reinforcing nanoparticles to strengthening of the composite microstructure at the fine microscopic level is neatly documented and appropriately discussed. Microhardness of the AZ91 alloy was found to increase from 61.4 MPa (without reinforcement) to 86.680 MPa for the hybrid nanocomposite. Addition of reinforcing alumina (Al2O3) nanoparticles resulted in an observable refinement in grain size while addition of zirconium dioxide (ZrO2) nanoparticles contributed to increasing the microhardness. Overall, addition of the hybrid reinforcement mixture resulted in a noticeable improvement in mechanical properties by ensuring an acceptable balance of strength and ductility of the developed nanocomposites.