Neutron irradiation effects on isotope tailored aluminum nitride ceramics by a fast reactor up to 2 × l026 n/m2

Abstract Physical property changes of AlN ceramics prepared with 14N and 15N by fast neutron irradiation were investigated. Sintered specimens were concurrently fast-neutron irradiated in JOYO fast reactor up to a fluence of 1.94 × l026 n/m2 at 530 °C. After irradiation and post-irradiation annealing up to 1500 °C, changes in macroscopic length, thermal diffusivity and microstructure were observed to examine the isotope effects. Swelling of Al15N was slightly larger than that of Al14N. Degree of recovery in length of Al15N after annealing was less than that of Al14N. Degradation of thermal diffusivity in both specimens was almost the same, but recovery in Al15N was more restricted. He release profiles up to 1500 °C was qualitatively similar, although the evolution amount was larger in Al14N. No clear isotope effect on microstructure change was observed. One of the possible reasons for the difference in property change due to the irradiation and recovery behaviour in Al14N and Al15N ceramics is the difference in diffusion rate of 14N and 15N, but further confirmation should be necessary.