A comparative study on the corrosion behavior of CoCrNi medium-entropy alloy and 316L stainless steel in simulated marine environment

This paper investigates the difference in the corrosion resistance and passive property of CoCrNi medium-entropy alloy and 316 L stainless steel in a simulated marine environment by using electrochemical measurements, immersion test and surface analysis technology. The results reveal that CoCrNi MEA has more superior anticorrosion resistance than that of 316 L. The difference in the corrosion resistance is related to the microstructure and surface passive film. Due to the presence of oxide inclusion, micro-galvanic corrosion is formed between the oxide inclusion and CoCrNi matrix, which promotes the anodic dissolution of CoCrNi MEA and induces the formation of pits. The matrix as the anode mainly undergoes the selective dissolution of Co element, while the selective dissolution of Co and Ni elements is occurred in the cathodic oxide inclusion.