Design and characterisation of AlCrFeCuNbx alloys for accident- tolerant fuel cladding

High entropy alloys (HEAs) have been considered as candidate materials used in the accident-tolerant fuel (ATF) cladding of reactor due to their promising oxidation and corrosion resistance. AlCrFeCuNla(x )(x = 0.3, 0.5, 0.7, 1) HEAs were designed to improve the accident tolerance of nuclear fuel in this paper. The microstructure, hardness, quasi-critical water corrosion resistance and high temperature water vapor oxidation of the AlCrFeCuNbx HEAs were systematically investigated. The results show that when x is 1.0, the alloy has optimal hardness, water corrosion and high temperature water vapor oxidation resistance. The X-ray diffraction (XRD) analyses showed that the AlCrFeCuNbx HEAs contained a base centered orthorhombic structure and intermetallic compound Cu9Al4. The AICrFeCuNb HEA had the best performance of 16.7 mg/dm(2) weight gain comparable with traditional Zr-1Nb alloy used for nuclear fuel cladding under operating conditions of nuclear power plant water environment of 360 degrees C and 18.6 MPa for three days keeping, and theta-Al2O3 and NbO formed on the surface of the HEA after water corrosion. The HEA with the same composition had also excellent oxidation resistance (36.77 mg/dm(2) weight gain) better than other compositions, which was two orders of magnitude less than that of the Zr-1Nb alloy in the environment of 1200 degrees C water vapor. Protective ci-Al2O3 and CrNbO4 formed on the surface of the AlCrFeCuNb HEA, which prevented further oxidation of the alloy. (C) 2020 Elsevier B.V. All rights reserved.