The electrochemical behavior of as-cast Al
xCoCrFeNiM (M = Ti, V, Si, Mn, Cu) high entropy alloys (HEAs) in 1 M NaCl and 0.5 M H
2SO
4 solutions is studied. Polarization measurements were carried out in a standard three-electrode electrochemical
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The electrochemical behavior of as-cast Al
xCoCrFeNiM (M = Ti, V, Si, Mn, Cu) high entropy alloys (HEAs) in 1 M NaCl and 0.5 M H
2SO
4 solutions is studied. Polarization measurements were carried out in a standard three-electrode electrochemical cell with a platinum auxiliary electrode using a P-30J potentiostat device. The potentials were measured relative to a saturated silver chloride reference electrode EVL-1M3 at room temperature (25 °C) with a sweep rate of 5 mV/s. It is shown that despite a wide passivation region, Al
0.5CoCrFeNi
1.6Ti
0.7 HEA undergoes significant corrosion in both sodium chloride and sulfuric acid solutions and exhibits low corrosion potential and current density. Energy-dispersive X-ray spectroscopy (EDS) analysis revealed that Ti-containing eutectic areas are the most susceptible regions to corrosion. Intergranular corrosion was found in Al
0.25CoCrFeNiMn and Al
0.25CoCrFeNiCu HEAs. Moreover, Al
0.25CoCrFeNiCu possesses the smallest passivation interval Δ
E among all the investigated HEAs. For samples with Ti, Mn, and Cu, a protective film layer is not formed on the surface of the phases enriched in these elements, or it is brittle and crumbles. For samples with Si and V, a passivating film is formed. Thus, Al
0.45CoCrFeNiSi
0.45 and Al
0.25CoCrFeNiV HEAs exhibited the highest resistance in 1 M NaCl and 0.5 M H
2SO
4 corrosive environments, respectively.
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