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Wear (erosion/abrasion) and corrosion act in synergy in several industrial installations where corrosive fluids circulate together with a solid phase causing mutual damage. High entropy alloys (HEAs) are promising materials to be used in that type of environments because of their outstanding chemical, electrochemical and mechanical properties. While several review articles are currently available on corrosion, mechanical properties, development of HEAs, microstructure, and HEA coatings, there is an undeniable lack of a comprehensive and critical review focusing on the tribological behaviour and tribocorrosion of bulk HEAs. This work aims to collect, summarise, and critically review the major accomplishments and progresses of HEAs over the last 20 years dealing with wear, corrosion, and wear-corrosion resistance. It highlights the most significant aspects that can influence the performance of HEAs including the change of the base alloying elements, the influence of the temperature, heat treatment, and wear test parameters (load, velocity, duration, distance). Furthermore, operating mechanisms, together with the relationship between microstructure and wear resistance, and between microstructure and corrosion resistance will be described. Finally, the articles that have been reported in the literature dealing with tribocorrosion of HEAs will be reviewed. The results of this study are expected to guide potential researchers and provide them with the sum of current trends in HEAs in terms of corrosion resistance, wear resistance and the synergy of both, in the hope of helping them to make the right decision to design and develop new HEAs or improve the research on the existing ones.

There is a huge demand for high-performance materials in extreme environments involving wear and corrosion. High chromium white cast irons (HCWCIs) display better performance than many materials since they are of sufficient hardness for wear protection and can be tailored in chemical compositions to improve corrosion resistance; however, their performance is often still inadequate. This article reviews the chemical composition and microstructure design aspects employed to tailor and develop HCWCIs with combined corrosion and wear resistance. The performance of these alloys under wear and corrosion is reviewed to highlight the influence of these parameters in the industry. Existing challenges and future opportunities, mainly focusing on metallurgical alloy development aspects like chemical composition, casting, and heat treatment design, are highlighted. This is followed by suggestions for potential developments in HCWCIs to improve the performance of materials in these aggressive environments. Many variables are involved in the design to obtain suitable microstructures and matrix composition for wear–corrosion resistance. Computational modeling is a promising approach for optimizing multi-design variables; however, reliable field performance data of HCWCIs in wear–corrosion environments are still inadequate. Quantitative evaluation of the wear–corrosion performance of HCWCIs requires the development of laboratory and field tests using standard conditions like abrasive type and sizes, severity of loading, slurry velocity, pH, and temperature to develop wear–corrosion maps to guide alloy development.