Heat-transfer corrosion behaviour of cast Al alloy

Heat-transfer corrosion behaviour of an ISO 2379 cast Al alloy was studied in antifreeze radiator coolant under heat-rejecting condition. Extensive analyses of microstructures and corroded surfaces were carried out under the optical microscope, scanning electron microscope equipped with energy dispersive spectroscopy and X-ray diffractometer. Heat-rejecting condition led to a cavitation process and cavities were observed within the α-Al matrix. Crevice corrosion was predominant at oxygen depleted regions in heat-transfer corrosion cell. Al2Cu, Al15(Fe,Mn)3Si2 dendrites, Al4Cu2Mg8Si7 and Si phases served as the effective cathodes resulting microgalvanic corrosion at the anodic site of α-Al matrix.