Evaluation of exfoliation susceptibility by means of the electrochemical impedance spectroscopy

Exfoliation is a type of attack that appears in rolled and extruded products, causing great losses of surface material due to the effect of delamination. Until now, the surface inhomogeneity promoted by this attack has been analysed using microscopic observation techniques. In this work, the electrochemical impedance spectroscopy technique has been used to characterise the exfoliation corrosion susceptibility of two light aluminium alloys. Some correlation between changes in the specimen's surface morphology and variations in the shape of Nyquist and Bode diagrams were found, making it possible to determine the stage of attack promoted on the material. (C) 2000 Elsevier Science Ltd. All rights reserved.