Atmospheric corrosion of field exposed magnesium alloy AZ91D
2008 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 50, no 5, 1406-1413 p.Article in journal (Refereed) Published
The magnesium alloy AZ91D was exposed in three different types of atmospheric environment, viz. urban, rural and marine exposure sites. Corrosion rates, corrosion products formed, and the influence of the microstructure on the corrosion behaviour of the alloy were investigated. The corrosion rate of AZ91D exposed in the marine environment was 4.2 mu m/year, and in the rural and urban environments 2.2 and 1.8 mu m/year, respectively. The main corrosion product found was magnesium carbonate hydromagnesite (Mg-5(CO3)(4)(OH)(2)center dot 4H(2)O), which was formed at all three exposure sites. The corrosion attack started in the alpha-phase in larger grains at the boundary between the alpha-phase and the eutectic alpha-/beta-phase. Microgalvanic elements were formed with the eutectic alpha-/beta-Mg phase as cathodic site and the alpha-Mg grains as anodes. The Al-Mn particles played a minor roll in the initiation process, even though these particles are the most noble in the microstructure and thus the driving force for a corrosion attack around these particles could be expected to be high. A close resemblance was observed between the corrosion mechanisms operating under the field-exposure conditions described here and the mechanisms operating under the previously reported laboratory conditions.
Place, publisher, year, edition, pages
2008. Vol. 50, no 5, 1406-1413 p.
Magnesium alloys; Atmospheric corrosion; Corrosion product; Corrosion rate; Field-exposure; Anodes; Atmospheric corrosion; Carbonates; Eutectics; Corrosion product; Field-exposure
Metallurgy and Metallic Materials
IdentifiersURN: urn:nbn:se:kth:diva-7683DOI: 10.1016/j.corsci.2007.12.005ISI: 000256184800024ScopusID: 2-s2.0-42049102024OAI: oai:DiVA.org:kth-7683DiVA: diva2:12782
QC 20100802. Uppdaterad från manuskript till artikel i tidskrift 20100802.2007-11-212007-11-212010-08-02Bibliographically approved