Corrosion behavior of CoCrCu0.1FeMoNi high entropy alloy in 0.5 mol/L NaOH solution

The corrosion behavior of CoCrCu0.1FeMoNi high entropy alloy (HEA) in 0.5 mol/L NaOH solution was investigated using X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, potentiodynamic polarization measurement, and electrochemical impedance spectroscopy. The results showed that the microstructure of this HEA displayed a dendritic morphology along with inter-dendritic regions. At the applied potential of -0.3, 0, and 0.1 V vs. saturated calomel electrode (SCE), no significant damage to the surface of the alloy was observed. At the applied potentials of 0.15 and 0.2 V vs. SCE, selective detachment and tearing of the microstructure on the alloy surface were observed, attributed to micro-galvanic corrosion. HEA demonstrates typical spontaneous passivation behavior and exhibits capacitance at all five applied potentials. The energy dispersive spectroscopy results indicate significant elemental segregation within HEA, with a decrease in the content of Cr2O3 in the passive film as the applied potential increases. Consequently, the protective efficacy of the passive film over the substrate in 0.5 mol/L NaOH solution was compromised.