Localized Atmospheric Corrosion of Magnesium-Aluminum Alloys Produced by Semisolid Casting: A 2D and 3D Investigation
Journal article, 2021

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.

3D imaging

atmospheric corrosion

magnesium-aluminum alloys

casting

localized corrosion

corrosion morphology

Author

M. Shahabi-Navid

Volvo Group

Mats Halvarsson

Chalmers, Physics, Microstructure Physics

Jan-Erik Svensson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

A. Allanore

Massachusetts Institute of Technology (MIT)

N. Birbilis

Australian National University

Lars-Gunnar Johansson

Chalmers, Chemistry and Chemical Engineering, Energy and Material, Environmental Inorganic Chemistry

M. Esmaily

Massachusetts Institute of Technology (MIT)

Corrosion

0010-9312 (ISSN)

Vol. 77 2 242-253

Subject Categories

Other Chemistry Topics

Metallurgy and Metallic Materials

Corrosion Engineering

More information

Latest update

3/30/2021