A review on wear, corrosion, and wear-corrosion synergy of high entropy alloys

Abstract

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.

Keywords: Abrasion; Corrosion; Erosion; High entropy alloy; Synergy; Tribocorrosion; Wear.

Graphical abstract

Fig. 1

Scratch resistance of C_xCrFeCoNiMn HEAs: a) 3D images of scratch grooves, and b) scratch volumes. Reproduced with permission from Ref. [41].

Fig. 2

a) Vickers hardness and b) Wear mass loss of as-cast, remelted and annealed AlFeCrCoNiTi_0.5 HEA. Reproduced with permission from Ref. [42].

Fig. 3

Wear resistance of Al_0.6CoCrFeNi annealed alloy and GCr15 vs. test temperature. Reproduced with permission from Ref. [43].

Fig. 4

a) Wear rate of Al_0.25CrFeCoNi HEA at different test temperatures; b) Variation of its friction coefficient with temperature. Reproduced with permission from Ref. [44].

Fig. 5

a) Evolution of specific wear rate as a function of temperature; b) Evolution of the steady-state friction coefficient of Al_0.4CrFeNiTi_0.2 as a function of temperature. Reproduced with permission from Ref. [46].

Fig. 6

a) Variation of the friction coefficient of CoCrFeNiMo_0.2 against the normal load; b) Evolution of the specific wear rate after dry sliding against the normal load. Reproduced with permission from Ref. [55].

Fig. 7

The cumulative volume loss/hour as the function of impact angle for Al_0.1CrCoFeNi, 316L stainless steel (SS) and mild steel (MS). Reproduced with permission from Ref. [59].

Fig. 8

Nyquist plot of Al_2-xCoCrFeNiTi_x as-cast HEAs. Reproduced with permission from Ref. [75].

Fig. 9

A schematic illustration of the proposed process occurring during the corrosion of CoCrFeNiCu in 0.6 M NaCl, a) before corrosion; b) during corrosion; c) after corrosion. Reproduced with permission from Ref. [3].

Fig. 10

Cationic fraction ratio in the passive layer of CoCrFeMnNi HEA with various carbon contents after passivation in saturated Ca(OH)₂ solution containing 3.5 wt% NaCl. Reproduced with permission from Ref. [90].

Fig. 11

Schematic illustrating the slurry erosion test rig used for tribocorrosion tests. Reproduced with permission from in Ref. [59].

Fig. 12

Volumetric wear losses of the as-cast HEA and the boronized samples. Reproduced with permission from [117].