THE STRUCTURE OF SIC-REINFORCED MG CASTING ALLOYS

The nature of the interface and interfacial reaction products formed b etween SiC particles and magnesium has been studied in two SiCp-reinfo rced magnesium casting alloys, ZC63 and ZE63. In ZC63, a thin amorphou s film was observed at the interface of the SiC particles. Energy-disp ersive X-ray and electron energy-loss spectroscopy methods were used t o characterize the films. They were found to contain Si, O and Mg, wit h the Si tetrahedrally coordinated to the O. The alloy ZE63 contains Z r and mischmetal (Ce, La, Nd, Pr), all of which are strong oxide forme rs, In the as-cast state, patches or continuous fine-grained oxide fil ms were found at the interface of the SiC reinforcing phase in this al loy. Electron diffraction was used to identify these oxides as the tet ragonal form of ZrO2 and cubic CeO2.