Selective dissolution during acid pickling of aluminum alloys by element-resolved electrochemistry

•A7xxx pickling mechanisms & Cu removal studied with element resolved electrochemistry.•Galvanic interactions between elements lead to a period of non-congruent dissolution.•Nitrate enhanced Cu dissolution by charge transfer mechanism.•Fe(III) effect on Cu dissolution rate investigated by experi...

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Bibliographic Details
Published in:Electrochimica acta 2022-02, Vol.404, p.139737, Article 139737
Main Authors: Sultan, B. Bin Mohamad, Thierry, D., Torrescano-Alvarez, J.M., Ogle, K.
Format: Article
Language:English
Subjects:
AA7449
Acid pickling
Aerospace alloys
AESEC
Alloy
Alloying elements
Aluminum
Aluminum alloys
Aluminum base alloys
Copper
Cu dissolutions
Dissolution
Electrochemistry
High strength alloys
High-strength
Iron compounds
Magnesium
Oxidation
Pickling
Pickling solutions
Selective dissolution
Solution components
Sulfuric acid
Surface reactivity
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Summary:•A7xxx pickling mechanisms & Cu removal studied with element resolved electrochemistry.•Galvanic interactions between elements lead to a period of non-congruent dissolution.•Nitrate enhanced Cu dissolution by charge transfer mechanism.•Fe(III) effect on Cu dissolution rate investigated by experimental Evans diagrams.•Effect of Fe(III) may be interpreted as a catalytic effect on nitrate reduction. The surface reactivity and the elemental dissolution of a high-strength aerospace alloy (AA7449-T651) during acid pickling was investigated with element-resolved electrochemistry (AESEC). The results demonstrated a sequential dissolution of Mg, Al, Zn and Cu, following the order of their respective galvanic reactivity in common acid pickling solutions. The enrichment of Cu during pickling with the H2SO4 solution was observed. The effect of oxidizing solution components HNO3 and Fe(III) on Cu dissolution were investigated using an experimental Evans diagram approach. [Display omitted]
ISSN:0013-4686
1873-3859
1873-3859
DOI:10.1016/j.electacta.2021.139737