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Oxide film formation and intergranular corrosion susceptibility of sensitized 5083 Al-Mg alloy: The role of tensile stress
1
,
*
1
,
Wenbin Hu
1
,
Bernard Tribollet
2
Academic Editor: David M. Bastidas
Published:
25 June 2026
by MDPI
in The 3rd International Online Conference on Corrosion and Materials Degradation
session Electrochemical Corrosion Mechanism at the Interface (Localized, Crevice, Advanced Characterization Techniques, EAC, Nanoscale)
Abstract:
- Intergranular corrosion significantly damages the strength of Al-Mg alloys with a Mg content > 3 wt% when these alloys are serviced in marine environments. Although a dense oxide film can prevent the degradation of Al alloys, the influence of tensile stress on the properties of the oxide film is unclear.
- Here, the early-stage corrosion of grain boundaries of 5083 Al-Mg alloy before and after sensitization was investigated using quasi in situ transmission-electron microscopy (TEM) and focused ion beam (FIB) TEM. Then, the oxide films formed on a sensitized 5083 Al-Mg alloy under constant elastic and plastic tensile stresses were investigated.
- Mg segregation on the grain boundary (GB) of the sensitized alloy led to the formation of a thicker and Mg-enriched oxide film on the GB surface, which caused severe intergranular corrosion (IGC). Tensile stress accelerated the anodic dissolution on the alloy surface and promoted intergranular corrosion, weakening the corrosion resistance of the oxide film. A heterogeneous oxide film was found on sensitized Al-Mg alloy under tensile stress, with the oxide film formed in the IGC region appearing thicker than that on the alloy matrix due to local alkalization. Tensile stress caused dislocations near the grain boundaries, but did not change the composition of the oxide film in the region subjected to intergranular corrosion. Density-functional theory calculations suggest that tensile stress destroyed the oxide film and weakened the electronic interactions between the oxide film and the alloy matrix, fostering the propagation of intergranular corrosion.
- Our findings advance the mechanistic understanding of corrosion oxide film formation on GBs on a near-atomic scale, and clarify the mechanisms of oxide film formation on Al-Mg alloys under constant tensile stress in aqueous solution.
Keywords: Oxide film; intergranular corrosion susceptibility; DFT
