Corrosion Resistance Of CuCrFeNiMn High Entropy Alloys

In this paper, three kinds of high entropy alloys with different elements molor were prepared by non-consumable vacuum arc furnace, which are CuCrFeNiMn, CuCr2Fe2Ni2Mn2 and Cu2CrFe2NiMn2. The corrosion resistance of three alloys was investigated and compared with S304 stainless steel alloys by the immersion test and electrochemical experiment in sulfuric acid, nitric acid, sodium hydroxide and sodium chloride solution. The corrosion morphology was observed by SEM. The element segeration in three alloys were analyzed by EDS. The effect of element content and element segeration on the corrosion resistance of alliys was discussed. The results show that:Three high entropy alloys show simple FCC and BCC structure. alloy are a single FCC structure, while CuCrFeNiMn and are FCC+BCC hybrid structure. There is serious segregation of Cu and Cr in three alloys.The corrosion rate of as cast high-entropy alloys in 1 M H2SO4 solution,30% HNO3 solution,1 M NaOH solution and 3.5% NaCl solution decreases in accordance with the order of Cu2CrFe2NiMn2, CuCrFeNiMn, CuCr2Fe2Ni2Mn2, which means that the corrosion resistance of high entropy alloys becomes better. The corrosion resistance of the high-entropy alloys is better than S304 Stainless Steel in acid solution, but worse in the NaOH solution and NaCl solution. The corrosion resistance of CuCr2Fe2Ni2Mn2 alloy with a single FCC structure is better than the other two high entropy alloys with BCC and FCC hybrid structure. Higher Cu content and serious segeration of Cu and Cr element decrease obviously the corrosion resistance of alloys. The typical corrosion characteristic of three alloys is intergranular corrosion and pitting corrosion. Annealing reduces the corrosion resistance of high entropy alloys in 1 M H2SO4 solution, but it is still better than the S304.Higher Cu content, lower Ni andCr contents result in the increase of Ecorr and the decrease of icorr. The corrosion resistance alloy becomes poor. The passivation zone widths of high entropy alloys in 1M H2SO4 solution, 1M NaOH solution and 3.5% NaCl solution are 300mv,777mv and 56-71mv respectively. Coparing with S304 Stainless Steel, the Ecorr of high entropy alloys with the best corrosion resistance in becomes more positive and icorr reduces 1M H2SO4 solution. The passivation are more narrow also. The corrosion resistance is better than S304. But in 1M NaOH solution and 3.5% NaCl solution, the Ecorr become more negative and icorr increases, the corrosion resistance is not good as S304 in 1M NaOH solution and 3.5% NaCl solution.