Abstract
High-entropy alloys (HEAs) are a newly developed family of multi-component alloys. The potentiodynamic polarization and electrochemical impedance spectroscopy of the Al <sub>x</sub> CrFe <sub>1.5</sub> MnNi <sub>0.5</sub> alloys, obtained in H <sub>2</sub> SO <sub>4</sub> and NaCl solutions, clearly revealed that the corrosion resistance increases as the concentration of aluminium decreases. The Al <sub>x</sub> CrFe <sub>1.5</sub> MnNi <sub>0.5</sub> alloys exhibited a wide passive region, which extended >1000 mV in acidic environments. The Nyquist plots of the Al-containing alloys had two capacitive loops, which represented the electrical double layer and the adsorptive layer. SEM micrographs revealed that the general and pitting corrosion susceptibility of the HEAs increased as the amount of aluminium in the alloy increased. © 2008 Elsevier Ltd. All rights reserved.