SPONTANEOUS INFILTRATION MECHANISM FOR SiC_p/Al COMPOSITES

SiCp/Al composites with high SiC content were prepared by spontaneous infiltration of liquid aluminum into oxidized SiC powder compact enhanced by adding magnesium. The infiltration mechanism was studied by inspecting the infiltration height of liquid aluminum in the pressed block of SiC powder versus temperature and time in the course of infiltration. SiCp/Al composites were analyzed by X-ray diffraction, energy dispersive spectroscopy and metallographic analysis. The results show that the liquid-solid interface reaction at the infiltration front enhances the wettability of the system, which leads to spontaneous infiltrating of liquid aluminum into the porous SiC powder bed. The infiltration height increases parabolically with time. The activation energy for infiltration is about 166 kJ/mol, which suggests that the infiltration procedure is controlled by an interface reaction. The oxidized SiC particles are distributed uniformly with clean boundaries in the metal matrix and no Al4C3 present in the composites.