Lattice expansion and microstructure evaluation of Ar ion-irradiated titanium nitride

Fully dense titanium nitride (TiN) ceramic was irradiated using a 100 keV Ar ion beam at 600 °C and at target fluences of 3 × 1017 ions cm−2, corresponding to 115 displacements per atom (dpa). X-ray diffraction and transmission electron microscopy were performed to evaluate the irradiation damage in the TiN. The lattice parameter increased and the lattice expanded by 0.19% after irradiation due to interstitial atoms and vacancies in Ar-irradiated TiN. Hills, bubbles and dislocations were observed. It is noteworthy that many TiN grains pulled out after irradiation and that amorphization of oxide grain boundaries was observed using high-resolution transmission electron microscopy, which indicates that the oxygen-containing impurities are potentially fatally dangerous to the radiation resistance property of TiN and other candidate materials.