Abstract

SLIMANE, Maamar  and  KELLOU-KERKOUCHE, Farida. Electrochemical Degradability of Al-20% Mg and Al-22% Si Alloys in an Acidic Environment in Relation with their Microstructure. Port. Electrochim. Acta [online]. 2020, vol.38, n.2, pp.79-98. ISSN 0872-1904.  https://doi.org/10.4152/pea.202002079.

The electrochemical degradability of Al-20% Mg and hypereutectic Al-22% Si industrial alloys was evaluated in an aggressive acidic environment, namely 1 M H₂SO₄, using potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) techniques. The microstructure and constituting phases of the surface alloys were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), coupled with Energy Dispersive X-ray Spectroscopy (EDX). It was found that the two alloys' corrosion behavior mainly depends on their crystalline phases. The presence of the active intermetallic ß- Al₃Mg₂ phase in the Al alloy with high Mg content induced a preferential Mg dissolution, which caused a severe intergranular attack on this alloy by the corrosive solution. Meanwhile, the Al alloy containing high Si content, which presented the eutectic Al-Si phase, showed a uniform and weaker dissolution. It was also observed that a rise in temperature reduced the corrosion performance of the two studied alloys, as these corroded faster than pure aluminum.

Keywords : aluminum alloys; acid corrosion; potentiodynamic polarization; EIS; dealloying.

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