Corrosion resistance based on the microstructural array of an Al-3wt%Cu-1wt%Li alloy

Abstract

The high specific properties of Al-Li alloys have led to tremendous development effort aimed in particular at aerospace applications. Al-Li castings and cast alloys that combine the good properties of Al-Li alloys with foundry technology have great potential in both the aircraft and automotive sectors [1, 2]. In general, the corrosion behavior strongly depends on the structural morphology and chemical composition [3]. In this work, anAl-3wt%Cu-1wt%Li alloy was solidified under upward unsteady state heat flow conditions. Heat was directionally extracted only through a water-cooled bottom made of steel (SAE 1020). The aim of the present work is to investigate the influence of the microstructure of this alloy upon corrosion resistance. Experimental results include secondary dendrite arm spacings (l2), corrosion potential (ECorr), corrosion rate (iCorr), polarization resistance (R1) and capacitances values (ZCPE). The corrosion behavior was analysed by electrochemical impedance spectroscopy technique and Tafel extrapolation method conducted in a 3% NaCl solution at room temperature. Coarser dendritic structures tend to improve the corrosion resistance of an Al-3wt%Cu-1wt%Li alloy.