The effect of helium irradiation on the thermal evolution of the microstructure of nc-ZrN

ZrN is a candidate material for use as inert matrix fuel host for the burn-up of plutonium and other minor actinides, waste products commonly present in spent nuclear fuel. These materials will operate within the nuclear reactor core and will therefore be subject to various types of radiation, high temperatures and a corrosive environment. Ceramics employed in the nuclear reactor environment will accumulate helium via (n, α) reactions. Nanocrystalline ZrN irradiated with 30 keV He to fluences between 1016 and 5×1016 cm–2to simulate the effects of alpha particle irradiation. The He irradiated sam- ples were annealed at temperatures between 600 and 1000 °C and were analysed using TEM and selected area diffraction. The results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. TEM analysis of He suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. The results also suggest that the doping of nc-ZrN with He aids the transformation from a nanocrystalline to microcrystalline state during heat treatment. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)