Corrosion Behavior of 2A97 Al-Li Alloy in Cl- and SO42- Mixed Salt Spray

A comprehensive evaluation was conducted using several investigative techniques to understand the corrosion characteristics and underlying mechanisms of 2A97 Al-Li alloy exposed to a marine atmosphere. These techniques included salt-spray (3.5 wt.% NaCl and 0.1 wt.% Na2SO4) assaying, gravimetric assessment of corrosion loss, macro- and microscopic morphological evaluations, x-ray photoelectron spectroscopic analysis, and electrochemical assessments. The study findings showed a declining trend for the corrosion propensity of the 2A97 Al-Li alloy. The accumulated corrosion by-products predominantly comprised compounds such as Al2O3 and Al(OH)(3), complemented by trace constituents such as Li2O, LiOH, Li2CO3, Al-based chlorides and sulphates, and elemental Cu. Notably, the Al2O3 present in the corrosion by-product stratum exhibited considerable compactness, thereby curtailing the permeation of corrosive ions. Concurrently, the stable Li2CO3 film exhibited excellent corrosion-inhibition properties. The cyclic dissolution and reprecipitation of elemental Cu bolstered the adhesive strength between the corrosion product layer and alloy substrate, further mitigating the corrosion kinetics of the foundational material.

Automated summary

This study comprehensively evaluated the corrosion characteristics and mechanisms of 2A97 Al-Li alloy in a marine atmosphere using various investigative techniques. The research found that the corrosion propensity of the alloy decreased over time. The corrosion by-products mainly consisted of compounds such as Al2O3 and Al(OH)(3), with trace constituents including Li2O, LiOH, Li2CO3, Al-based chlorides and sulphates, and elemental Cu. The compactness of Al2O3 limited the permeation of corrosive ions, while the stable Li2CO3 film exhibited excellent corrosion-inhibition properties. The cyclic dissolution and reprecipitation of elemental Cu enhanced the adhesive strength between the corrosion product layer and alloy substrate, further reducing the corrosion kinetics.