Corrosion behavior of Hf0.5Nb0.5Ta0.5Ti1.5Zr refractory high-entropy in aqueous chloride solutions.

Abstract The Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr refractory high-entropy alloy with excellent corrosion resistance in the 3.5 wt% NaCl solution is identified in this work. This refractory high-entropy alloy exhibits much better general corrosion resistance than that of the 316L stainless steel, due to its corrosion current density being about one fifth of that in the latter. Meanwhile, the pitting potential of Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr reaches an unusually high value of +8.36 V, much higher than that of reported high-entropy alloys. The superior passivity of Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr is accredited to the formation of a single-phase solid solution containing high amount of homogenously distributed passivity-promoting elements, and also the existence of metallic Ta and OH− species in the passive film, which contribute to the high immunity to passive film breakdown. Highlights • Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr contains finely distributed passivity-promoting elements. • Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr exhibits better general corrosion resistance than 316L SS. • E pit of Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr reaches +8.36 V, beating all other reported RHEAs. [ABSTRACT FROM AUTHOR]