Abstract
The electrode impedance of Al-Cu, Al-Mn and Al-Mg alloys have been measured at 103Hz under potentiostatic-cathodic polarization conditions to investigate the relation between the cathodic polarization and the pitting corrosion of aluminum alloys. The cathodic current of Al-Mg and Al-Mn alloys decreased with increasing setting time but that of Al-Cu alloys remained nearly constant. Since the pitting corrosion depends on the cathodic reaction, the pitting corrosion resistance of Al-Mg and Al-Mn alloys in chloride solution may be estimated to be larger than that of Al-Cu alloy. From the time variation of AC impedance at metal-solution interface, the relationship between the local current and the measured polarization curve is discussed. It is likely that the film property influences significantly the pitting corrosion of aluminum alloys.
