Effects of ion irradiation on Cr, CrN, and TiAlCrN coated Zircaloy-4 for accident tolerant fuel claddings

Heavy ion (6 MeV Au+) irradiation studies were carried out on three candidate coatings (Cr, CrN, TiAlCrN) and Zircaloy-4 for accident tolerant fuel cladding to investigate the irradiation resistance and microstructure evolution at 400 degrees C. Transmission Electron Microscopy (TEM) results showed that the irradiation defects were significantly restricted by grain boundaries in the columnar grains compared to equiaxed grains and the high-density boundaries could obviously reduce the formation of voids. Fast Fourier Transformation (FFT) results of high-resolution TEM images showed that Cr and CrN coatings maintained better lattice integrity than those of TiAlCrN coating and Zircaloy-4. ATF coatings showed less irradiation defects than that of Zircaloy-4 substrate. Cr coating exhibited better irradiation resistance than that of TiAlCrN coating in terms of irradiation dislocation loops. CrN coating showed the best irradiation resistance among all samples, due to its compact crystal structure and higher density of grain boundary, which contributed to reduce dislocations and voids. (C) 2021 Elsevier Ltd. All rights reserved.