Recovery behavior of point defects after low-dose neutron irradiation at ∼423K of sintered 6H–SiC by lattice parameter and macroscopic length measurements

Recovery behavior of neutron-irradiation-induced point defects of high-purity β-SiC

“…It appears that there is some irregularity between 1123 K and 1173 K. Beyond 1373 K, the slope again becomes steeper. Compared to the previous study for a-SiC [21], from room temperature to 1273 K, the residual lattice parameter change of the c-axis after each annealing slightly exceeded that of the a-axis, but beyond 1273 K, the difference mostly disappeared. In general lattice parameter recovery was observed for both phases.…”

“…Our previous work on a-SiC irradiated at 423 K showed small linear expansion of 0.45%, which was considered to be less than saturation level because the neutron fluence was low, 1.9 Â 10 23 n/m 2 [21].…”

“…The length change of the rectangular specimens was continuously measured in situ at high temperature using a precision dilatometer (NETZSCH, Germany, DIL 402C) from 423 K, which was slightly above the irradiation temperature, up to 1623 K with a step-heating temperature interval of 50 K in a helium atmosphere (10 5 Pa), as described previously in the literature [13,14,21]. The specimen temperature was monitored with Type-S thermocouple placed close to the specimen and controlled within 0.01°C.…”

“…Recently, we conducted precise recovery measurement on neutron-irradiated polycrystalline SiC up to 1.9 Â 10 23 n/m 2 (E > 0. sintering additives [21]. It was revealed that length change recovery behavior between 473 and 1573 K could almost be explained by a first-order reaction, and there are three stages with activation energies of 0.14, 0.26, and 1.13 eV.…”

“…It was revealed that length change recovery behavior between 473 and 1573 K could almost be explained by a first-order reaction, and there are three stages with activation energies of 0.14, 0.26, and 1.13 eV. In this paper, we examine recovery processes of a neutron-irradiated high-purity 3C(b)-SiC polycrystal, using the method same as the previous study [13,21], to compare activation energies of length/volume recovery of SiC ceramics containing different additives and/or polytypes, and clarify the effects of additives/impurities and polytypes on stability of induced defects.…”