抄録
Macroscopic and microscopic behavior of neutron irradiated β-Si3N4 was observed and analyzed.Specimens they were irradiated under relatively low temperature showed essentially different behavior from the specimen irradiated under high temperature as reported previous papers. Neutron irradiation was performed in the experimental fast reactor, JOYO.High resolution TEM observation showed there were few interstitial dislocation loops in the specimen irradiated lower temperature than 390°C.Thermal diffusivity and macroscopic length changes due to post-irradiation isochronal thermal annealing up to 1500°C were measured for these specimens. Low-temperature irradiated specimens showed gradual length recovery and almost completely recovery in thermal diffusivity while high-temperature irradiated specimens showed almost no length recovery and large residue in recovery of thermal diffusivity.These results indicate that the interstitial atom in beta-silicon nitride begin to move and create interstitial dislocation loop around 390°C.
