Influence of constitutional liquation on corrosion behaviour of aluminium alloy 2017A

The purpose of this work was to investigate microstructural aspects of constitutional liquation in the aluminium alloy 2017A and to determine its effect on corrosion behaviour of this alloy. Non-equilibrium melting of the alloy in the naturally aged condition was provoked by rapid heating above the eutectic temperature and immediate cooling in air. Corrosion testing was performed by exposure to a marine onshore atmosphere. The microstructure examinations were carried out using light microscopy, scanning electron microscopy, X-ray energy dispersion and X-ray diffraction analysis. It was found that, due to rapid heating rate, coarse θ (Al2Cu) particles were melted by constitutional liquation and this way introduced strong susceptibility of 2017A alloy to intergranular corrosion.