The corrosion characteristics of as-cast SiC{dollar}sb{lcub}rm p{rcub}{dollar}/Al (A356) system were examined in chloride media using optical and scanning electron microscopy, energy dispersive x-ray analysis, cyclic potentiodynamic anodic polarization, and pit propagation rate test methods. Breakdown potential (E{dollar}sb{lcub}rm b{rcub}{dollar}) increased slightly as the SiC{dollar}sb{lcub}rm p{rcub}{dollar} volume fraction increased but decreased as the Cl{dollar}sp-{dollar} concentration increased. The severity of localized corrosion attack increased with increasing SiC{dollar}sb{lcub}rm p{rcub}{dollar} volume fraction and Cl{dollar}sp-{dollar} concentration. Correlation of pit initiation sites with microstructural features revealed the critical role of second-phase particles in the composite materials and the corresponding unreinforced alloy matrix. At low Cl{dollar}sp-{dollar} concentrations, {dollar}rm FeMgsb3Sisb6Alsb8{dollar} intermetallic particles were the most susceptible microstructural features responsible for pit initiation in the unreinforced alloy. The particles were light gray and exhibited scipt and blade-like morphologies. As the Cl{dollar}sp-{dollar} concentration increased numerous geometrical pits nucleated within the primary Al phase of the unreinforced alloy. Pitting corrosion attack in the composite occurred preferentially at the Al-FeSiAl{dollar}sb5{dollar} interface at low Cl{dollar}sp-{dollar} concentrations. These particles displayed a blade-like morphology. As the Cl{dollar}sp-{dollar} concentration incresed, pits initiated primarily at the SiC-Si and Sic-Al interfaces.
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