Elevated-temperature wear behavior and mechanisms of APS-sprayed Al_0.6TiCrFeCoNi high entropy alloy coating

Thermal sprayed high entropy alloy coatings have garnered substantial attention for their remarkable mechanical properties and wear resistance. In this study, we explored the wear behavior and mechanisms of Al0.6TiCrFeCoNi coatings produced through atmospheric plasma spray (APS) at both room temperature and 500 degrees C. The microstructural and mechnical characterization of the APS-sprayed coating was performed using XRD, OM, SEM, CSLM and hardness testing techniques. The dry sliding wear test of the coating against Al2O3 ball were conducted on a pin-on-disc tribometer at room temperature and 500 degrees C. The coating exhibited a single body-centered cubic (BCC) phase, with a typical lamellar structure marked by oxides and pores. Wear tests showed that the APS-sprayed coating exhibits superior wear resistance at elevated temperatures compared to room temperature due to the formation of compact oxide layer on the wear track. Detailed investigations on wear track reveal that abrasive wear, oxidation wear and fatigue wear are the prominent wear mechanisms on both conditions, while tribo-oxidation is dominated at 500 degrees C. Furthermore, We demonstrated that the looser, more porous microstructure of the APS-sprayed coating contributes to its enhanced wear resistance, preventing crack propagation and increasing strain tolerance. This provides a promising strategy for outstanding wear resistant coatings by designing looser lamellar coating structure.