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Corrosion behaviour of mechanically polished AA7075-T6 aluminium alloy

Liu, Yanwen and Laurino, Adrien and Hashimoto, Teruo and Zhou, Xiaorong and Skeldon, Peter and Thompson, George and Scamans, Geoff and Blanc, Christine and Rainforth, W. Mark and Frolish, Mike F. Corrosion behaviour of mechanically polished AA7075-T6 aluminium alloy. (2010) Surface and Interface Analysis, vol. 42 (n° 4). pp. 185-188. ISSN 0142-2421

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Official URL: http://dx.doi.org/10.1002/sia.3136

Abstract

In the present study, the effects of mechanical polishing on the microstructure and corrosion behaviour of AA7075 aluminium alloy are investigated. It was found that a nano-grained, near-surface deformed layer, up to 400 nm thickness, is developed due to significant surface shear stress during mechanically polishing. Within the near-surface deformed layer, the alloying elements have been redistributed and the microstructure of the alloy is modified; in particular, the normal MgZn2 particles for T6 are absent. However, segregation bands, approximately 10-nm thick, containing mainly zinc, are found at the grain boundaries within the near-surface deformed layer. The presence of such segregation bands promoted localised corrosion along the grain boundaries within the near-surface deformed layer due to microgalvanic action. During anodic polarisation of mechanically polished alloy in sodium chloride solution, two breakdown potentials were observed at −750 mV and −700 mV, respectively. The first breakdown potential is associated with an increased electrochemical activity of the near-surface deformed layer, and the second breakdown potential is associated with typical pitting of the bulk alloy.

Item Type:Article
Additional Information:Thanks to Wiley editor. The definitive version is available at http://onlinelibrary.wiley.com/ The published final form can be found at Surface and Interface Analysis website : http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1096-9918
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Other partners > University of Manchester (UNITED KINGDOM)
Other partners > University of Sheffield (UNITED KINGDOM)
Other partners > Innoval Technology (UNITED KINGDOM)
Laboratory name:
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Deposited By:Leila Abdelouhab

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