Acta Metallurgica Sinica (English Letters) ›› 2023, Vol. 36 ›› Issue (3): 366-378.DOI: 10.1007/s40195-022-01466-8

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Corrosion Behaviour of a Non-equiatomic CoCrFeNiMo High-Entropy Alloy in H2S-Containing and H2S-Free Environments

Zhu Wang1(), Guo-Hui Zhang1, Yong Yao2, Xue-Hua Fan3, Jie Jin1, Lei Zhang1, Yan-Xia Du1   

  1. 1Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
    2CITIC Pacific Special Steel Group Co., Ltd, Jiangsu 214429, China
    3China Petroleum Engineering & Construction Co., Ltd Beijing Company, Beijing 100085, China
  • Received:2022-06-24 Revised:2022-07-23 Accepted:2022-07-26 Online:2023-03-10 Published:2022-09-20
  • Contact: Zhu Wang, wangzhu@ustb.edu.cn

Abstract:

The corrosion behaviour of a non-equiatomic CoCrFeNiMo high-entropy alloy (HEA) in H2S-containing and H2S-free environments was studied by electrochemical tests, surface characterization, and solution analysis. The results showed that the HEA exhibited primary and secondary passivation in the H2S-free environment, and the transition was owing to the enhanced dissolution of Fe species. Compared with the primary passive film, the Cr/Fe ratio in the secondary passive film increased at the expense of the selective dissolution of Fe. Therefore, the corrosion resistance of HEA decreased with the applied potential. Cr was the most stable element in the film of HEA, regardless of H2S. The presence of H2S accelerated the dissolution of all the cationic elements in the HEA. H2S promoted the formation of thicker but less protective surface film and induced the loss of passivity.

Key words: High-entropy alloy (HEA), Corrosion, H2S, Secondary passivation, X-ray photoelectron spectroscopy (XPS), Induced coupled plasma (ICP)