Preparation, structure, and properties of high-entropy alloy multilayer coatings for nuclear fuel cladding: A case study of AlCrMoNbZr/(AlCrMoNbZr)N

AlCrMoNbZr/(AlCrMoNbZr)N multilayer coatings with equal individual layer thicknesses varying from 5 to 50 nm were deposited by using magnetron co-sputtering technology on N36 substrates (Zr1Sn1Nb-0.3Fe (wt.%)), to enhance the corrosion resistance of zirconium alloys in the event of a loss-of-coolant accident (LOCA). Comprehensive characterization by using X-ray diffraction and transmission electron microscopy revealed a multilayer structure consisting of a face-centred cubic (FCC) (AlCrMoNbZr)N layer and an amorphous AlCrMoNbZr layer. The structure and properties of the AlCrMoNbZr/(AlCrMoNbZr)N multilayer coatings with different individual layer thicknesses were studied, and the structure of all multilayer coatings contained coexisting amorphous and FCC phases. In addition, the multilayer coatings exhibited good interfacial bonding strength and good hydrophobicity. Corrosion tests were performed in static pure water at a temperature of 360 °C and a pressure of 18.7 MPa for 30 days. The results showed that the AlCrMoNbZr 50 nm/(AlCrMoNbZr)N 50 nm multilayer coating had superior anti-corrosion properties (4.4 mg/dm2 weight gain) to those of the AlCrMoNbZr 5 nm/(AlCrMoNbZr)N 5 nm and AlCrMoNbZr 10 nm/(AlCrMoNbZr)N 10 nm multilayer coatings. The AlCrMoNbZr/(AlCrMoNbZr)N multilayer structures inhibited Al migration and suppressed boehmite phase formation more effectively than single-layer AlCrMoNbZr or (AlCrMoNbZr)N.