Interface stability, mechanical and corrosion properties of AlCrMoNbZr/ (AlCrMoNbZr)N high-entropy alloy multilayer coatings under helium ion irradiation

High entropy alloy (HEA) coatings are promising for use as accident-tolerant fuel cladding due to their outstanding high-temperature corrosion resistance. In this work, we investigated the interface stability, mechanical properties and corrosion resistance of AlCrMoNbZr/(AlCrMoNbZr)N multilayer coatings with individual layer thickness of 5 nm, 10 nm and 50 nm, subjected to helium (He) ion irradiations: 400 keV He+ ions with fluences of 8 x 10(15) ion/cm(2 )and 8 x 10(16) ion/cm(2). We determined that He bubbles are not observed in any of the multilayer coatings after a helium ion irradiation process with 400 keV He ions and a fluence as high as 8 x 10(16) ion/cm(2). Although intermixing and chemical reaction in the peak damage region of the AlCrMoNbZr/(AlCrMoNbZr)N multilayer coating with 5 nm monolayer thickness are induced by the high fluence He ion irradiation, the FCC structure remained, and no intermetallic compounds are detected. Moreover, we found that the AlCrMoNbZr/(AlCrMoNbZr)N multilayer coating with the monolayer thickness of 50 nm has better interface stability during the irradiation process. Nanoindentation tests reveal that the hardness of all multilayer coatings decreased for low and high fluences, which is mainly due to the thermal effect caused by irradiation. In addition, the electrochemical corrosion WA show that AlCrMoNbZr/(AlCrMoNbZr)N multilayer coating 50 nm coatings has better corrosion resistance than AlCrMoNbZr/(AlCrMoNbZr)N multilayer coating 5 nm coatings under high fluence He irradiation. The corrosion resistance of the multilayer coating depends on the stability of the multilayer interface. Our results show that the AlCrMoNbZr/(AlCrMoNbZr)N multilayer coating with a monolayer thickness of 50 nm had better interface stability, mechanical properties and corrosion resistance than the AlCrMoNbZr/(AlCrMoNbZr)N multilayer coating with a per layer thickness of 5 nm under high fluence He irradiation. This work reveals that high-entropy alloy multilayer coatings could have potential applications as an accident-tolerant fuel cladding coating in light water reactors.