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Localized Atmospheric Corrosion of Magnesium-Aluminum Alloys Produced by Semisolid Casting: A 2D and 3D Investigation

Version 2 2024-06-02, 23:42
Version 1 2023-10-26, 02:48
journal contribution
posted on 2024-06-02, 23:42 authored by M Shahabi-Navid, M Halvarsson, JE Svensson, A Allanore, Nick BirbilisNick Birbilis, LG Johansson, M Esmaily
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.

History

Journal

Corrosion

Volume

77

Pagination

242-253

Location

Houston, Tex.

ISSN

0010-9312

eISSN

1938-159X

Language

English

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

2

Publisher

National Association of Corrosion Engineers