The oxidation of SiC particles and its interfacial characteristics in Al-matrix composite

The passive oxidation behavior of SiC particles has been studied in an electric furnace at atmospheric pressure and in dry air, the weight change due to the transformation from SiC into SiO₂ is descibed as a function of exposed temperature and holding time. According to the oxidation data of SiC particles, the oxidation parameters and the degree of oxidation for SiC particles can be controlled. Controllable preoxidation of SiC particles is one of the keys for designing interface and interphase to achieve high performance aluminum composite. Consequently, the evolution of interfacial reaction products in 2014 aluminum alloy composite reinforced with oxidized-SiC particles after extended thermal exposure at elevated temperatures were further characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray diffraction. While it could act to prevent the interfacial reaction between SiC particles and aluminum alloy, the preoxidation of SiC particles led to the formation of other interfacial reaction products. The observation of the microstructure revealed that at elevated temperatures nano-MgO formed initially on the surface of the oxidized SiC particles and then turned into nano-MgAl₂O₄ crystal due to the reaction between the SiO₂ and aluminum alloy containing Mg. TEM observations indicated that the oxidized layer on SiC particles was uniform and had a good bonding with SiC and aluminum alloy.