In situ TEM investigation of irradiation-induced defect formation in cold spray Cr coatings for accident tolerant fuel applications

Application and Development Progress of Cr-Based Surface Coatings in Nuclear Fuel Element: I. Selection, Preparation, and Characteristics of Coating Materials

“…Additionally, a Cr coating was found to enhance the chemical resistance of the Zr alloy to an environment of primary cooling water, which improved the flexibility of operations under current water chemistry limitations [18]. The results of ion irradiation and neutron irradiation tests have shown that Cr coatings with body centered cubic (BCC) structures have a certain irradiation stability [105,106]; those prepared via the cold spraying method, especially, exhibited irradiation damage resistance [107]. The overall assessment of Cr coatings in ex-situ conditions, i.e., out of a reactor, confirmed their good adhesion, which helps to maintain the integrity of the coating during normal operations.…”

“…At present, the most extensively used preparation methods of the Cr-based coatings on Zr alloys are physical vapor deposition (PVD) [14,[18][19][20]22,23,55,[104][105][106]108,109,115,116], cold spraying (CS) [15,24,73,95,107,[117][118][119], and 3D laser melting and coating (3D-LMC) [6,17,25,33,34,69,120]; each are currently used by CEA (French Alternative Energies and Atomic Energy Commission) in France, Westinghouse Electric Corporation in the US, and KAERI in South Korea, respectively. These preparation methods and the characteristics of the prepared coatings are described in the next section.…”

“…Maier et al [107] characterized a CS Cr coating using a TEM in-situ ion irradiation test. The as-deposited sample (Figure 8a) contained elongated grains that underwent severe plastic deformation during the CS process, and each grain exhibited a dense dislocation network structure formed through local dynamic recrystallization; the annealed samples (cut out from the same sample and annealed at 800 • C for 8 h; see Figure 8) contained more equiaxed grains and fewer deformation defects because the deformation effect during the CS process was eliminated.…”

“…The above results confirmed that in a Cr coating material that undergoes severe plastic deformation, the pre-existing deformation-induced defects act as traps to resist irradiation-induced damage, thus yielding a better irradiation stability. Reproduced from [107] with copyright permission from Elsevier.…”

“…The (c) density and (d) size of irradiation-induced defects as a function of radiation damage. Reproduced from[107] with copyright permission from Elsevier.…”