Effects of fast neutron irradiation on zirconium carbide

High-purity zone refined zirconium carbide has been fast neutron irradiated in the dose and temperature range of 1-10 x 10(25) N/m(2) (E > 0.1 MeV) and 635-1480 degrees C, respectively. Non-irradiated and as-irradiated properties were measured including the lattice parameter, hardness and elastic modulus as determined through nano-indentation, thermal conductivity, and indentation fracture toughness. The effects of neutron irradiation on the microstructure were also determined though using transmission electron microscopy. The general finding of this paper, limited to this particular zone refined ZrC of nominal C/Zr ratio of 0.93, is that this ceramic is quite stable under neutron irradiation in the temperature and dose range studied. Measurement of lattice parameter before and after irradiation indicated a lack of significant crystalline strain due to irradiation. Only modest changes were observed in the mechanical properties of hardness, elastic modulus, and indentation fracture toughness. The thermal conductivity underwent a slight reduction near 1000 degrees C irradiation, though was essentially unchanged for 1300-1480 degrees C irradiation. Transmission electron microscopy revealed black-spot-type defects (likely Frank or other small loops) for irradiation at 670 degrees C, maturing to faulted Frank loops at 1280 degrees C. As the irradiation temperature increased from 1280 degrees C to the highest irradiation temperature, of 1496 degrees C, a transition to prismatic loops occurs. (C) 2010 Elsevier B.V. All rights reserved.