Microstructural evolution of epitaxial Ti₃AlC₂ film on sapphire under ion irradiation and nanoindentation-induced deformation

Feasibility of Ti₃AlC₂ phase as the protective coatings of accident tolerant fuels (ATFs) was investigated by means of ions irradiation, nanoindentation and transmission electron microscopy. Au ions irradiation was carried out on thin Ti₃AlC₂ film to simulate the high displacement damage induced by the energetic particles in the nuclear reactors. Nanoindentation on the Ti₃AlC₂ film was followed subsequently as a source of external stress to simulate the high pressure applied on the cladding in nuclear reactor cores of pressurized water reactors (PWRs). TEM was used to characterize the microstructural evolution of Ti₃AlC₂ film after irradiation and nanoindentation. TEM analysis shows that Ti₃AlC₂ film remains pristine layered structure and no amorphization was detected after irradiation to ∼14 dpa. The combined nanoindentation and TEM show that no rupture and exfoliation of the Au-irradiated Ti₃AlC₂ film occur even the extern stress and total elongation induced by nanoindentation reach to 16.6 GPa and ∼5%, respectively. The above results show good irradiation resistance and good ductility as well as excellent adhesion of the Ti₃AlC₂ coating on the substrate after high dose irradiation and under high external stress. This indicates the good feasibility of Ti₃AlC₂ thin films as the coatings of ATF claddings.