Corrosion and tribological behavior of CoCrFeMoNi high-entropy alloys as a potential vascular implant material

Abstract

The high-entropy CoCrFeMoNi alloy showcases remarkable strength, flexibility, and corrosion resistance. Consequently, it’s anticipated to display exceptional surface degradation resistance in corrosive environments. This research examines the corrosion and tribocorrosion behavior of CoCrFeMoNi samples in different cold-rolling and annealing stages. The tribological evaluations were conducted in Hank's physiological solution at room temperature, employing 1 and 2 N loads. The increased corrosion resistance of the cold-rolled samples could be attributed to their fine-grained microstructure and elevated hardness, particularly pronounced in samples with higher cold-roll levels. Reciprocally, increasing the annealing temperatures would lead to a decline in corrosion resistance. The tribological performance indicates that the stability and durability of the passive layer were compromised in the rolled samples. Nevertheless, the rapid reformation of the re-passive layer following wear demonstrates significant tribocorrosion resistance across all HEA samples. Simultaneously, the re-protective layer in the annealed samples exhibited greater resistance than the initial passivation due to the dual-phase structure and stress induced by wear. These findings underscore the alloy’s potential for biomedical applications such as vascular implants requiring a blend of strength, flexibility, corrosion, and tribocorrosion resistance, along with an extended operational lifespan.