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.

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Titanium Nitride (TiN) films were obtained using the grid-assisted magnetron sputtering deposition technique on Al substrates in two conditions: under constant and variable nitrogen concentration along the thin solid film thickness. The formation of a film with variable N concentration (herein referred as graded film) was confirmed using energy filtered transmission electron microscopy, X-ray photoelectron spectroscopy and grazing incidence X-ray diffraction. The TiN thin films microstructures were also analysed using scanning and transmission electron microscopies (SEM and TEM). The viability of synthesizing TiN thin films with variable N concentration is herein proposed as an alternative method for tailoring the properties of such functional coating materials.