Evaluation of tribological characteristics of HVOF sprayed (CrMnFeCoNi)Alx high entropy alloy (HEA) coatings

High-entropy alloys (HEAs) are characterized as alloys containing five or more principal elements in equal or close to equal atomic percentage. HEAs as bulk materials and coatings are considered potential candidate for high-temperature applications owing to their superior combination of mechanical and thermal properties. However, limited studies have focused on the tribological behavior of HEAs fabricated by means of High Velocity Oxy-Fuel (HVOF) process. In the present study, the CrMnFeCoNi HEA coatings with different Al content were developed using high-velocity oxygen fuel (HVOF) process. The microstructure, mechanical properties and tribological behavior of the as sprayed HEA coatings were systematically evaluated. The wear behavior of these HEA coatings against alumina (Al₂O₃) ball was tested under the dry sliding conditions at room and elevated temperatures. Ex situ characterization was performed using XRD/Raman for phase analysis, FE-SEM for cross-section microscopy and surface morphology identification. In addition, EDS analysis was performed to evaluate the phase compositions of the HEA coatings. The powder particle size distribution, microstructural changes, phase compositions, microhardness, and wear performance of the various HEA coatings are discussed further in the paper. A strong emphasis is placed on the correlation between the interfacial processes and wear behavior of the HEA coatings.