Analysis of recovery process of neutron-irradiation-induced defects in α-SiC by isothermal annealing up to 1400 °C

The macroscopic length change of SiC due to neutron irradiation and recovery by subsequent annealing was examined. Samples were fast-neutron-irradiated to a fluence of 5.3 × 1024 n/m2 (En > 0.1 MeV) at 470 °C, and 1.9 × 1023 n/m2 at <200 °C. The length change did not saturate over 6 h at each isothermal annealing temperature between irradiation temperature and ∼1200 °C. It was shown that the macroscopic length change could be fitted roughly as a straight line against the square root of total isothermal annealing time, indicating vacancy–interstitial recombinations are the main mechanisms for the recovery. Using recovery behavior during isochronal and isothermal annealing, the activation energy for the annealing of dilatation was estimated. The activation energy of length recovery increases with increasing annealing temperature, with several small stages.