Effect of length scale of Al₂O₃ particulates on microstructural and tensile properties of elemental Mg

In the present study, magnesium-based composites were fabricated with three different sizes (ranging from nano- to micro-meter scale) of 1.1 vol.% Al₂O₃ particulate reinforcement using blend-press-sinter methodology avoiding ball milling. Microstructural characterization of the materials revealed reasonably uniform distribution of Al₂O₃ reinforcement, significant grain refinement and the presence of minimal porosity. Mechanical property characterization revealed that the incorporation of Al₂O₃ particulates as reinforcement 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-size and submicron size Al₂O₃ remained 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.