Corrosion behavior of AlCoCrFeNi2.1 eutectic high-entropy alloy in Cl--containing solution

In this paper, we investigated the corrosion behavior of the AlCoCrFeNi2.1 eutectic high-entropy alloy in 3.5 wt% NaCl solution and 3.5 wt% NaCl + 0.01 mol/L NaHSO3 solution at different temperatures by electrochemical testing, XPS and SEM/EDS. The findings indicate that the AlCoCrFeNi2.1 eutectic high-entropy alloy can be passivated in 3.5 wt% NaCl solution at different temperatures, with the passive film dominated by metal oxides. The component proportions in the passive film change with temperature, with pitting corrosion occurring at the phase rich in Al-Ni as the primary form of corrosion. However, it cannot be passivated in 3.5 wt% NaCl + 0.01 mol/L NaHSO3 solution at any temperatures. Additionally, the surface of the corrosion product film mainly consists of metal hydroxide on the surface, while the proportion of components in the corrosion product film varies with temperature. Furthermore, the corrosion is caused by the dissolution of the Al-Ni-rich phase. The AlCoCrFeNi2.1 eutectic high-entropy alloy does not demonstrate adequate anti-corrosion property in Cl--containing acid Solution.