The effect of Al and Zr content on corrosion of AlNiCoCuZr high-entropy alloys in a 5 wt% NaCl solution

High-entropy alloys are attractive structural materials for the design of apparatus for various chemical technologies due to their relative ease of production, corrosion resistance and high values of mechanical properties (hardness, strength). In the present work, the influence of aluminum and zirconium content on the corrosion resistance of Al(20−35)-Ni(5−15)-Co(15−30)-Cu(20−35)-Zr(5−40) high-entropy alloys was studied experimentally for the first time. Corrosion tests were performed in a 5 wt% NaCl aqueous solution during 1500 h at 298 K. It is established that the electronegative metals included in the alloy - Al and Zr are passivation components and with increasing their content in AlNiCoCuZr composition the corrosion rate in the studied conditions is decreased. It is shown that degradation of alloys occurs mainly as a result of nickel and cobalt hydroxide formation, the solubility of which is several orders of magnitude higher than that of aluminum hydroxide and zirconium hydroxide. •The influence of Al and Zr on corrosion resistance of AlNiCoCuZr HEAs was studied.•The main process of alloys degradation is related with the oxidation of Ni and Co.•Al20Ni5Co15Cu20Zr40 alloy has the highest corrosion resistance than other studied alloys.