Corrosion of continuous alumina-fibre reinforced Al-2 wt.% Cu-T6 metal-matrix composite in 3.15 wt.% NaCl solution

The corrosion performance of a continuous alumina-fibre reinforced metal-matrix composite (MMC) and its monolithic matrix alloy (Al-2%Cu-T6) was studied in 3.15 wt.% sodium chloride solution. Corrosion initiation sites, mapping of corrosion current density and pH at corrosion sites, mass loss resulting from immersion, and polarization behaviour were studied. Results show that the MMC exhibited inferior corrosion resistance as compared to its monolithic matrix alloy. Corrosion of the MMC initiated preferentially along the fibre/matrix interface or in regions of plastic deformation. The build-up of acidity at localized corrosion sites on the MMC was enhanced by the formation of micro-crevices caused by fibres left in relief as a result of corrosion.