SiC_p/2024Al基复合材料的点蚀形貌

用扫描电镜对浸泡在w(NaCl)=3 5%水溶液中的SiCp/2024Al金属基复合材料(AlMMCs)的点蚀形貌进行了观察,作为对比,对其基体合金的点蚀行为也进行了研究·结果表明,SiCp/2024AlMMCs的点蚀形貌与SiC颗粒的体积分数和尺寸有关,SiC含量高或尺寸小的AlMMCs,其蚀孔数量较多,尺寸较小·与基体合金相比,AlMMCs的点蚀孔较大,数量较少,分布也较不均匀,甚至出现局部严重腐蚀的现象·能谱分析表明,SiCp/2024AlMMCs的腐蚀机制为富Cu阴极相与贫Cu阳极相间的电偶腐蚀·另外,SiC与Al间也存在电偶腐蚀倾向·

Pit Morphology of SiCp/2024 Al Metal Matrix Composites

The pit morphology of SiCp/2024 Al metal matrix composites (MMCs) in 3.5% NaCl solution was investigated by scanning electron microscopy and compared with that of corresponding unreinforced matrix alloy. The results show that the pit morphology depends on the volume fraction and size of SiC particles. The pits on the MMCs are more numerous and smaller in size as the volume fraction increases or particle size is reduced. And, the pits are a little bigger, less numerous and more non-uniform in spatial distribution when compared with those on the 2024 Al. Moreover, severe local corrosion occurs on the MMCs except the one reinforced by 30% SiC volume fraction. The corrosion mechanism of the MMCs is galvanic corrosion between the phase rich in Cu and the matrix, and between the SiC particle and the matrix.