Metastable pitting characteristics of aluminium alloys measured using current transients during potentiostatic polarisation

By R. Gupta, N. Sukiman, M. Cavanaugh, B. Hinton, Christopher Hutchinson, Nick Birbilis. 2012

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Abstract In this study we report a comparison between the metastable pitting observed upon AA2024-T3, AA5005-H34, AA5083-H116, AA6022-O, AA7075-T651 and pure Al, over a range of potentials. Metastable pitting increased with microstructural (hence electrochemical) heterogeneity of the alloys studied, which roughly correlates with hardness. In alloys exhibiting a low pitting propensity, metastable pitting activity completely ceased as the underpotential from E pit was increased, whereas for corrosion prone alloys, metastable activity continued independently of underpotential. The selection of the test potential is also a key factor in using the method described herein. It is shown that the E pit value bears little correlation with the number of pits formed during long-term exposure as measured using optical profilometry, whereas the metastable pitting rate bears a correlation to the actual pit density.

Subfields: Aerospace Engineering, Materials Chemistry, Metals and Alloys

View Paper: https://www.semanticscholar.org/paper/c6ed3906d79db285f50db5c5ad5b94b49cb3df88