Dealloying-driven local corrosion by intermetallic constituent particles and dispersoids in aerospace aluminium alloys. (December 2020)

• Record Type: Journal Article
• Authors: Kosari, A.; Tichelaar, F.; Visser, P.; Zandbergen, H.; Terryn, H.; Mol, J.M.C.
• Is Part Of: Corrosion science. Volume 177(2020)
• Publication Date: 2020-12
• Subjects: Aerospace aluminium alloys -- Quasi in-situ TEM -- Cross-sectional ex-situ TEM -- FIB/SEM analysis -- Dealloying -- Pitting corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2020.108947
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Combined quasi in-situ and ex-situ analytical TEM to probe local corrosion in aluminium alloys. Corrosion initiates by dealloying of dispersoids and constituent phases. Dealloyed parts of IMPs drive the local dissolution of the nearest alloy matrix. Electrochemical instability of IMPs largely governs kinetics of local corrosion in aluminium alloys. Abstract: Nanoscopic characterization of heterogeneous intermetallic particles (IMPs) which microstructurally and compositionally evolve during local corrosion is crucial in unravelling the mechanisms and sequence of initial and local corrosion events. Herein, we study site-specific initiation events focused on microscopic constituent intermetallic compounds and nanoscopic dispersoids in AA2024-T3 at the nanoscale using a combined quasi in-situ and ex-situ analytical TEM approach. Our findings show a dealloying-driven local corrosion initiation at the studied IMPs that have been considered as cathodic phases traditionally. Besides, local degradation which is a result of galvanic interactions between dealloyed regions of IMPs and their adjacent alloy matrix is largely governed by the intrinsic electrochemical instability of intermetallic compounds.