Development of an Al3+ ion-selective microelectrode for the potentiometric microelectrochemical monitoring of corrosion sites on 2098-T351 aluminum alloy surfaces Autores: R.M.P. da Silva, J. Izquierdo, M.X. Milagre, J.V.S. Araujo, R.A. Antunes, R.M. Souto, I. Costa

Abstract

The development of heterogeneous electrochemical activity in the welded zones of aluminum alloy 2098-T351 by friction stir welding (FSW) associated with the formation of a near-surface deformed layer (NSDL) upon exposure to an aqueous chloride-containing solution was characterized using scanning electrochemical microscopy (SECM) in potentiometric operation. A solid-contact Mg2+ ion-selective microelectrode allowed in situ monitoring of the corrosion reactions sites for magnesium dissolution from different zones of the FSW weld upon exposure to a chloride-containing aqueous environment. In this way, localized corrosion reactions developing in the galvanically coupled joint/heat affected zones (WJ/HAZ) of the weld were detected and imaged with spatial resolution. The most active domains for local Mg2+ concentrations were associated with the HAZ of the retreating side (RS), and these corresponded to Mg oxidation from the Mg-enriched oxide bands in NSDL.