Energetic particle irradiation study of TiN coatings: are these films appropriate for accident tolerant fuels?

Abstract

Coating nuclear fuel cladding alloys with hard thin films has been considered as an innovative solution to increase the safety of nuclear reactors, in particular during a of loss-of-coolant accident (LOCA). In this context, and due to its suitable mechanical properties and high corrosion resistance, titanium nitride thin films have been proposed as candidate coatings for zirconium alloys in new accident tolerant fuels for light water reactors. Although the properties of TiN hard coatings are known to be adequate for such applications, the understanding of how the exposure to energetic particle irradiation changes the microstructure and properties of these thin films is still not fully understood. Herein, we report on heavy ion irradiation in situ within a Transmission Electron Microscopy of magnetronsputtered TiN thin films. The coatings were irradiated with 134 keV Xe + ions at 473K to a fluence of 6.7×10 15 ions•cm −2 corresponding to 6.2 displacements-per-atom where significative microstructural alterations have been observed. Post-irradiation analytic characterisation with Energy Filtered TEM and Energy Dispersive X-ray spectroscopy carried out in a Scanning Transmission Electron Microscope indicates that TiN thin films are subjected to Radiation Induced Segregation. Additionally, the nucleation and growth of Xe bubbles appears to play a major role in the dissociation of the TiN thin film.

Deviating from the pure MAX phase concept: Radiation-tolerant nanostructured dual-phase Cr 2 AlC

“…This effect can be observed in real time in the in situ TEM ion irradiation video provided as supplementary material. A similar effect was observed to occur in TiN nanocrystalline thin films when subjected to 134-keV Xe ion irradiation (27). The STEM-EDX analysis shown in Fig.…”

Investigating sluggish diffusion in a concentrated solid solution alloy using ion irradiation with in situ TEM

“…Preferential channels for diffusion of interstitials and vacancies will exist and they will be dominant near interfaces. As a result of this effect, chemical segregation processes have been reported to occur in some CSAs under irradiation [29], although this has not been observed for He irradiations on the FeCrMnNi CSA in this present work: if significant radiationinduced segregation had occurred, electron-contrast differences would be observed along the interfaces of the studied alloys as previously reported by our group in similar irradiation conditions [55]. These facts can explain the anomalous growth of He bubbles at the interfaces of the FeCrMnNi CSA upon subsequent annealing as herein reported and in contrast with the observed results in the matrix.…”

Radiation resistance and mechanical properties of magnetron-sputtered Cr2AlC thin films

“…Currently, nuclear energy generation faces several challenges. After Fukushima-Daiichi Accident better protection of zirconium fuel assemblies is searched in the development of so named Accident Tolerant Fuel (ATF) solutions [1][2][3]. On the other side, it is expected that the materials which are designed for and to be used for the future fission reactors (e.g., Gen III+, IV), will undergo severe radiation damage (up to 100 displacements per atom) at high temperatures (573 -973 K).…”