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International Journal of Corrosion
Volume 2010, Article ID 953850, 8 pages
http://dx.doi.org/10.1155/2010/953850
Research Article

Electrochemical Estimation of the Corrosion Rate of Magnesium/Aluminium Alloys

1Departamento de Ciencia de Materiales, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain
2Centro Nacional de Investigaciones Metalúrgicas, CSIC, Avda. Gregorio del Amo 8, 28040 Madrid, Spain
3Corrosion and Protection Centre, School of Materials, The University of Manchester, P.O. Box 88, Sackville Street, Manchester M60 1QD, UK

Received 19 June 2009; Accepted 5 October 2009

Academic Editor: Raman Singh

Copyright © 2010 A. Pardo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The corrosion rate of AZ31, AZ80, and AZ91D magnesium/aluminium alloys immersed in 3.5 wt.% NaCl was determined comparing gravimetric and electrochemical measurements. The findings revealed that, for all investigated materials, a fraction of the metallic surface exposed to the corrosive medium did not reveal a normal electrochemical response to the applied signal. This may be associated with phenomena such as partial disintegration of specimens into fine metallic particles, electrochemical formation of M g + ions, and/or anomalous chemical attack occurring simultaneously with the normal electrochemical corrosion attack. The abnormal electrochemical behaviour was more evident for lower amounts of aluminium in the bulk composition of the investigated materials. Thus, the electrochemical estimates of pure Mg and the AZ31 alloy were not reliable and tended to underestimate corrosion losses.