Effect of particulate size of Al₂O₃ reinforcement on microstructure and mechanical behavior of solidification processed elemental Mg

In the present study, magnesium-based composites were fabricated with three different sizes (ranging from nanometer to micrometer scale) of 1.1 vol.% Al₂O₃ particulates reinforcement using disintegrated melt deposition technique. Microstructural characterization of the materials revealed reasonably uniform distribution of Al₂O₃ reinforcement with good interfacial integrity, significant grain refinement, and the presence of minimal porosity. Mechanical properties characterization revealed that the incorporation of nano and submicron size Al₂O₃ particulates in magnesium matrix led to a simultaneous increase in hardness, 0.2% yield strength, UTS, and ductility of pure magnesium. The results further revealed that the 0.2% yield strength, UTS, and ductility combination of the magnesium containing nano and submicron size Al₂O₃ remained much higher when compared to high strength magnesium alloy AZ91 reinforced with much higher amount of micron size SiC particulates. An attempt is made in the present study to correlate the effect of different length scales of Al₂O₃ particulates on the microstructural and mechanical properties of magnesium.