Localized Atmospheric Corrosion of Magnesium-Aluminum Alloys Produced by Semisolid Casting: A 2D and 3D Investigation
Author(s)
Shahabi-Navid, M.; Halvarsson, M.; Svensson, J.E.; Allanore, Antoine; Birbilis, N.; Johansson, L.G.; Esmaily, M.; ... Show more Show less
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The localized corrosion of the two magnesium-aluminum alloys AM50 and AZ91 produced by a semisolid casting method was investigated under atmospheric corrosion conditions, in the presence of NaCl. Gravimetry confirmed the beneficial effect from ambient levels of carbon dioxide (CO₂) in suppressing corrosion through the formation of magnesium hydroxy carbonates. Both 2D and 3D characterization revealed that ambient CO₂ has a strong influence on the morphology and rate of localized corrosion. In CO₂-free atmosphere, the alloys suffered localized corrosion resulting in clustered and interconnected cavities that extended deep into the material. In contrast, corrosion in the presence of ambient levels of CO₂(400 ppm) resulted in evenly distributed shallow corrosion sites. The results indicate that CO₂ neutralizes the cathodic areas resulting in diminished cathodic activity and inhibiting NaCl(aq) droplet coalescence.
Date issued
2020-11Department
Massachusetts Institute of Technology. Department of Materials Science and EngineeringJournal
Corrosion
Publisher
NACE International
Citation
Shahabi-Navid, M. et al. "Localized Atmospheric Corrosion of Magnesium-Aluminum Alloys Produced by Semisolid Casting: A 2D and 3D Investigation." Corrosion 77, 2 (November 2020): 242–253. © 2021 NACE International
Version: Author's final manuscript
ISSN
0010-9312
1938-159X