Electrochemical behavior of Al3Fe intermetallic compound

Abstract

The cathodic processes localized to iron rich intermetallic phases on commercial aluminum alloys during corrosion inneutral chloride environments are controlled by the structural and compositional changes occurring on these phases in alocally stable alkaline environment. These phenomena are investigated by conventional electrochemical techniques onsynthetically grown Al3Fe crystals. The surface of the crystals is enriched by metallic iron at E -0.66 VSCE, a transpassive behavior is observed, characterized by the selective dissolution of aluminum and oxidation of enriched iron into an unprotective oxide, possibly FeOOH. Athigher potentials, the surface passivates again by Fe2O3 formation. The significance of these results on aluminum alloycorrosion is discussed. In addition to their role as cathodes, it is argued that these compounds may be contributingdirectly to pit initiation and the determination of the pitting potential on aluminum alloys. © 1993, The Japan Institute of Light Metals. All rights reserved.