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Abstract
Porosity was found in the local area of high volume fraction SiCp/Al composites fabricated by pressureless infiltration at times, which seriously affects the performance and results in waste of resources. In this paper, the microscopic feature and the phase composition of the porosity area in the composites were studied by scanning electron microscope, energy-dispersive x-ray spectroscopy and X-ray diffraction. The formation of new phases on the surface of SiC particles extracted from the composites with porosity by using chemical dissolution method was investigated by scanning electron microscope, energy-dispersive x-ray spectroscopy and X-ray diffraction. The effect of porosity on the mechanical property of composites was investigated by three-point-bending tests. The results showed that the pores existing among the gaps of SiC particles in the porosity area were in different sizes and shapes. Additionally, the aluminium oxides in different states formed on SiC particles surface in the porosity area without infiltration by aluminium. The porosity degrades the composites mechanical performance. The formation mechanism of porosity in the composites was discussed to provide the view for avoiding the porosity.