Effect of the microstructure of Zn-Al and Zn-Al-Mg model alloys on corrosion stability

•Microstructure affected atmospheric corrosion of Al- and Mg- alloyed zinc.•Materials with finer microstructures were usually more stable.•Mg-rich phases dissolved preferentially.•Al-rich phases activated at cathodic sites at alkali pH.•Al and Mg reduced zinc run-off by stabilisation of protective c...

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Bibliographic Details
Published in:Corrosion science 2016-09, Vol.110, p.71-81
Main Authors: Prosek, Tomas, Hagström, Joacim, Persson, Dan, Fuertes, Nuria, Lindberg, Fredrik, Chocholatý, Ondřej, Taxén, Claes, Šerák, Jan, Thierry, Dominique
Format: Article
Language:English
Subjects:
A. Metal coatings
A. Zinc
Aluminum
Atmospheric corrosion
B. Polarisation
B. SEM
B. Weight loss
C. Atmospheric corrosion
Chemical and phase compositions
Chemical compositions
Chemical stability
Corrosion
Corrosion products
Corrosion stability
Cyclic corrosion tests
Effect of the microstructures
Magnesium
Measurements of
Microstructure
Weight loss
Zinc
Zinc alloys
Zinc coatings
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Summary:•Microstructure affected atmospheric corrosion of Al- and Mg- alloyed zinc.•Materials with finer microstructures were usually more stable.•Mg-rich phases dissolved preferentially.•Al-rich phases activated at cathodic sites at alkali pH.•Al and Mg reduced zinc run-off by stabilisation of protective corrosion products. Zn-5Al and Zn-3Al-2Mg model alloys were cast and heat treated in order to obtain specimens with distinct microstructures and identical chemical compositions. The microstructure was characterised in detail to identify composition, size and distribution of present phases. Mass losses of samples with different microstructures and identical chemical compositions that were subjected to a cyclic corrosion test and a test under non-rinsing conditions differed by a factor of up to two. The mechanism is discussed based on measurements of corrosion stability of individual phases and chemical and phase compositions of corrosion products.
ISSN:0010-938X
1879-0496
1879-0496
DOI:10.1016/j.corsci.2016.04.022