Effect of intermetallic phases on corrosion of aluminum-silicon carbide (Al-SiCp) composites

Particulate-reinforced metal-matrix composites (MMC) have been used in several applications where high mechanical performance and other related properties are paramount requirements. High specific modulus, low thermal expansion coefficient, good wear resistance, low density and low cost are the major attractive characteristics of this class of materials in aerospace, automobile and construction industries. Localized corrosion, in these alloys, is usually insidious and may lead to catastrophic service failures. This can only be minimized by incorporating corrosion control at the design stage and by modifying the processing routes.; The corrosion behavior of four different types of aluminum alloy was studied. Two of these alloys (F3K.20S and F3S.20S) are reinforced with 20% by vol. SiC while the remaining two samples (F3S.00S, and F3K.00S) are not reinforced. Weight loss, potentiodynamic and cyclic polarization techniques were used to study their corrosion behavior in 3.5% wt. NaCl solution. Micro-analytical studies such as optical micrography, scanning electron micrography (SEM), X-ray diffraction, X-ray fluorescence (XRF) were utilized to analyze the role of intermetallic phases in both corroded and non-corroded samples of these mentioned alloys.; The results showed that un-reinforced alloys have higher corrosion resistance as compared to their reinforced counterparts. Pits observed in all the alloys show different shapes and structures. Some intermetallic phases in the reinforced alloys were suspected to have contributed to the formation of localized corrosion.