Corrosion behavior of a non-equiatomic CoCrFeNiTi high-entropy alloy: A comparison with 304 stainless steel in simulated body fluids

A new type of non equiatomic Co40Fe35Cr16Ni8Ti1 HEA was designed and synthesized, and its corrosion resistance was compared with 304 SS in Hank's simulated body fluids to verify its feasibility as an alternative for existing coronary stent materials. Electrochemical tests showed that the corrosion current density of Co40Fe35Cr16Ni8Ti1 HEA was 10(-6) in order of magnitude, which was about 1/6 of that of 304 SS, and the impedance value of Co40Fe35Cr16Ni8Ti1 HEA was 10(5) in order of magnitude, which was about 7 times that of 304 SS. Scanning electron microscopy testing showed that after 120 h of continuous salt spray corrosion, the surface of 304 SS showed obvious corrosion morphology compared with Co40Fe35Cr16Ni8Ti1 HEA, and it was corroded with clear grain boundaries. After 6 h of potentiostatic polarization, a passive film was formed on the surfaces of Co40Fe35Cr16Ni8Ti1 HEA and 304 SS respectively, and the composition of the passive film of the two materials was analyzed by X-ray electron spectroscopy. Compared with 304 SS, the passive film formed on Co40Fe35Cr16Ni8Ti1 HEA is rich in Co and Cr elements, and the high Content of Cr and Ni makes Co40Fe35Cr16Ni8Ti1 HEA have higher corrosion resistance in Hank simulated body fluid. The high content of Fe2+ oxide in the passive film is the main reason why 304 SS is less resistant to corrosion than Co40Fe35Cr16Ni8Ti1 HEA in Hank's simulated body fluid. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Through comparison of the corrosion resistance in Hank's simulated body fluids between Co40Fe35Cr16Ni8Ti1 high-entropy alloy and 304 stainless steel, it is found that the former shows higher corrosion resistance due to the rich content of Cr and Ni elements in the passive film, while the latter performs poorly under the same conditions.