2014 Volume 55 Issue 3 Pages 543-548
Magnesium composites containing 0–20 vol% Al2O3 particles were produced via mechanical milling (MM) followed by spark plasma sintering (SPS), and the effect of the microstructure on their mechanical properties was investigated. Microstructural observation of the MM powders and SPS compacts was achieved using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM)/energy dispersive X-ray spectroscopy (EDS). The mechanical properties of the MM powders and SPS compacts were evaluated on the basis of the results of the Vickers hardness test. SEM micrographs indicated that Al2O3 fine particles were dispersed in the Mg composites with 10 and 20 vol% Al2O3. The hardness values for the MM powder and the SPS compact containing 10 vol% Al2O3 were nearly the same owing to their similar microstructures. However, the hardness of the SPS compact was higher than that of the MM powder for the Mg composite with 20 vol% Al2O3. TEM/EDS and XRD analyses revealed that the needle-like Mg17Al12 and equiaxed nano MgO particles formed in the Mg matrix with 20 vol% Al2O3 during the SPS process. The increase in hardness of the SPS compact compared to that of the MM powder is attributed to strengthening resulting from the formation of the Mg17Al12 and MgO phases.