Effect of Al/SiC Interface and Intermetallic Particles on Elevated Temperature Corrosion of Hypoeutectic Al-Si-Mg Composites

Abstract

Abstract The role of intermetallics and silicon carbide (SiC) particles on the corrosion behavior of Al-SiC composites has been investigated. Alloys F3K (UNS A0338) and F3S (UNS A0359) were selected for investigation. Results of weight loss and elevated-temperature electrochemical studies at different rotational and linear velocities have been presented. The results showed that alloys reinforced with SiC exhibited higher corrosion rates compared to unreinforced alloys. Al/SiC interface was the preferred site for localized corrosion and pitting was predominantly observed. The Al/SiC interface was more densely populated with secondary-phase particles than the matrix, and the pit cavity contained appreciable concentrations of intermetallic particles of copper aluminide (CuAl2), nickel aluminide (NiAl3), and copper-nickel aluminide (Cu3NiAl6), which suggested that they were the preferred sites for pitting. The resistance of the alloys to elevated temperatures and increased velocities is affected by SiC partic...