On the corrosion behavior of Al<inf>2</inf>Cu by local electrochemical impedance spectroscopy using droplet cell microscopy

In this short communication, we study the electrochemical behavior of an individual Al2Cu intermetallic phase (coexisting with α-Al) in 0.1 M NaCl solution (with and without inhibitor) using droplet cell microscopy (DCM). The influence of CeCl3 (250 ppm) addition to the electrolyte is studied through potentiodynamic polarization (DC method). The results suggest that the addition of CeCl3 retards the cathodic reaction rate, thereby decreasing the corrosion rate. This study also highlights on the stability of the system, which is essential to perform local electrochemical impedance spectroscopy (LEIS) using DCM. Fabrication of a proper silicone rubber gasket at the flat capillary tip is important to achieve reproducibility, in order to use DCM in contact mode (as confined droplet). The stability and linearity of the system is proved by sweeping frequencies in both directions and by performing Kramers-Kronig transformation (KKT), respectively. LEIS reveals a charge transfer resistance of 2.83 kΩ cm2 as an effect of inhibitor addition, whereas the charge transfer resistance is 1.9 kΩ cm2 in 0.1 M NaCl solution.