Galvanic corrosion over World War II aircraft wrecks

Aluminium usually exhibits a better corrosion resistance than other common metals when exposed to outdoor environments. However, wrecks components made of aluminium alloys, particularly Al-Cu alloys, can be strongly affected by corrosion. The observation of different objects from WWII wrecks indicates more significant degradation in the presence of ferrous parts because of galvanic corrosion. The study focused on two WWII aircraft objects recovered from French coasts: a Supermarine Spitfire aircraft wing, found in 1988 at sea less than 3 miles from the coast of Plérin, and an aircraft propeller found offshore near the beach of Fécamp. We investigated the galvanic corrosion effect over these objects and the influence of their Fe/Al areas ratio between the more noble material (usually ferrous alloy) and the less noble material (usually aluminium alloy). This deterioration was severe due to their exposure to the marine environment and the relatively high amount of Cu (3.4 ‑ 4.5 wt. %) in the Al alloys, provoking pitting, intergranular, and exfoliation corrosion. This study aims to help understanding active corrosion on aircraft wrecks, with the final aim to improve their conservation.