J. Mater. Sci. Technol. ›› 2023, Vol. 139: 59-68.DOI: 10.1016/j.jmst.2022.07.061

• Research Article • Previous Articles     Next Articles

Unusually high corrosion resistance in MoxCrNiCo medium entropy alloy enhanced by acidity in aqueous solution

S. Shuanga, G.J. Lyub,c, D. Chunga, X.Z. Wangd, X. Gaoa, H.H. Maoe,f, W.P. Lig, Q.F. Hea, B.S. Guoh, X.Y. Zhongg, Y.J. Wangb,c, Y. Yanga,g,i,*   

  1. aDepartment of Mechanical Engineering, College of Engineering, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong, China;
    bState Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;
    cSchool of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China;
    dState Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, Northwestern Polytechnical University, Xi'an 710072, China;
    eUnit of Structures, Department of Materials Science and Engineering, KTH, Stockholm SE-10044, Sweden;
    fThermo-Calc Software, Råsundav. 18, Solna, SE-16767, Sweden;
    gDepartment of Materials Science and Engineering, College of Engineering, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong, China;
    hInstitute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou 510632, China;
    iDepartment of Advanced Design and System Engineering, College of Engineering, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong, China
  • Received:2022-05-29 Revised:2022-07-20 Accepted:2022-07-28 Published:2023-03-10 Online:2023-03-06
  • Contact: *Department of Mechanical Engineering, College of En-gineering, City University of Hong Kong, Kowloon Tong, Kowloon, Hong Kong, China. E-mail address: yonyang@cityu.edu.hk (Y. Yang).

Abstract: High corrosion resistance of alloys is essential for their structural applications; however, most alloys suffer from degradation of their corrosion resistance with the increasing acidity of their surroundings. Nonetheless, we developed a series of medium-entropy alloys (MEAs) in this work, which exhibit high strength, superior fracture toughness and ultra-high corrosion resistance, outperforming the variety of corrosion resistant alloys hitherto reported. Most interestingly, our MEAs exhibit an unusual anti-corrosion behavior and their corrosion resistance increases with acidity in Cl- containing solutions. Through extensive thermodynamic calculations, density functional theory (DFT) simulations and experiments, we reveal that the unusual anti-corrosion behavior of our MEAs can be attributed to their surface chemical complexity, which facilitates the physio-chemical-absorption of H2O and O2 and thus the rapid formation of metastable medium entropy passive films that contain the lowest amount of defects, as compared to the passive films on conventional alloys reported in the literature.

Key words: Corrosion, Passivation, Alloy design, Multi-principal element alloys, Medium-entropy alloys