Insight into the crevice corrosion mechanism of AA7075-T651 high-strength aluminum alloys in neutral nitrate solution: The effect of Cl−

Abstract

The crevice corrosion behavior and mechanism of AA7075-T651 aluminum alloy was investigated by electrochemical measurements and surface analysis technologies in a neutral nitrate solution with different contents of NaCl. The Cl⁻ was identified as crucial for the initiation and development of the crevice corrosion, with the phenomenon absent in the 0.05 M NaCl solution but initiated in the 0.5 and 1 M NaCl solutions. However, the crevice corrosion was more pronounced in the 0.5 M NaCl solution due to the establishment of a larger galvanic corrosion effect. The rapid dissolution of the anodic phase resulted in the increased Cl⁻ inside the crevice, while the cathodic phase enhanced the localized dissolution through micro-galvanic corrosion. This synergistic effect significantly facilitated the development of crevice corrosion.