Structural analysis of the MgAl5 matrix cast composites containing SiC particles

Microstructural analyses of cast composites on the base of MgAl5 alloy reinforced with SiC particles are presented. Composite samples containing 30 wt.% of hexagonal SiC particles of the 6H type were obtained by simple and non-expensive gravity casting of the mechanically mixed suspension. Composites showed a uniform arrangement of the SiC particles within the matrix and a good adhesive bond between the components. Scanning electron microscopy was used to determine the Al and Si concentration in the magnesium matrix. From X-ray and transmission electron microscopical examinations, the Mg2Si compound, a product of the reaction between magnesium and the SiO2 film covering the SiC particles, was identified. The Al12Mg17 compound was also found by TEM examination. The paper includes also a model description of the formation process of MgAl5/SiCp composite structure.