Fabrication of SiC particulate reinforced AZ91D composite by vacuum-assisted pressure infiltration technology

The AZ91D Mg matrix composites reinforced by SiC particulate with the sizes of 11 μm, 21 μm and 47 μm were successfully fabricated respectively by vacuum-assisted pressure infiltration technology. Microstructures and particulate distributions were analyzed with scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The coefficient of thermal expansion (CTE) measurements was performed from 75 °C to 400 °C at a heating rate of 5 °C/min. The results show that the uniform distribution of SiC particulate in metal matrix and density over 98% in theoretical density of composites were fabricated. Only MgO phase was detected at the interface and no brittle phases of Al₄C₃ and Mg₂Si were discovered. The desirable coefficients of thermal expansion of composites were achieved. The intensity of dislocation generation nearby SiC particulate increases significantly with the increasing of SiC particulate size. Therefore, this technology is a potential method to fabricate Mg matrix composites reinforced by SiC particulates with the desirable microstructures and CTE.