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Role of nanostructure in pitting of Al-Cu-Mg alloys

Version 2 2024-05-30, 09:09
Version 1 2015-08-24, 14:34
journal contribution
posted on 2024-05-30, 09:09 authored by KD Ralston, Nick BirbilisNick Birbilis, MK Cavanaugh, M Weyland, BC Muddle, Ross MarceauRoss Marceau
Aluminium alloys possess a unique combination of strength and low density, which historically have made these alloys ideal for many structural applications. However, addition of alloying elements in appreciable concentrations, in particular Cu and Mg, make Al-alloys inherently susceptible to localised corrosion. In this work, we adopt a bottom-up approach in an attempt to quantify the critical microstructural feature size (viz. precipitate size) that is capable of triggering a cascade of pitting events and eventual degradation of corrosion resistance. This is accomplished by exploiting the well characterised hardening response in a model alloy, Al–1.1Cu–1.7Mg (at.%), for which pitting resistance of the alloy was tracked with aging time and hence microstructural evolution. Corrosion performance and microstructural characterisation were carried out using a combination of electrochemical testing, coupled with high-resolution scanning transmission electron microscopy (HRSTEM) and atom probe tomography (APT). Results indicate, at least for this particular alloy, that second phase features below a critical width of approximately 3 nm can be tolerated from a corrosion perspective. This study has potentially wide consequences in the understanding of aluminium alloy corrosion initiation and the development of highly corrosion resistant aluminium alloys.

History

Journal

Electrochimica acta

Volume

55

Pagination

7834-7842

Location

Amsterdam, The Netherlands

ISSN

0013-4686

eISSN

1873-3859

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2010, Elsevier

Issue

27

Publisher

Elsevier