Effect of native air-formed oxidation on the corrosion behavior of AA 7075 aluminum alloys

The effect of native air-formed oxidation on the corrosion behavior of AA 7075 aluminum alloy and selective corrosion of anodic Mg2Si precipitates was presented. Oxidation of Mg2Si leads to formation of Mg(OH)(2) protrusions depleting magnesium in this precipitate as shown by AFM, SEM and EDX results. Spectroscopic studies prove that composition changes occurring within the passive layer may be a cause of observed improvement of electrochemical properties under prolonged exposition to air. Influence of cathodic phases containing AlFe(Cu,Mn,Cr) is limited in these conditions. (C) 2014 Elsevier Ltd. All rights reserved.