九大・応用力学研究所における原子力材料照射影響下評価の取り組み
概要
The neutron irradiation of Fe based fusion and fission reactor materials lead to an increase in the ductile-to-brittle transition temperature (DBTT) with a decrease in the upper shelf energy. It is well known that the Cu content has a strong influence on the embrittlement phenomena; especially, the Cu-rich precipitates have been thought to be directly responsible for the embrittlement. In contrast, mechanical property studies for the steels with different Cu levels have shown that so-called matrix defects are dominant in the embrittlement of low-Cu steels as well as in that of high-Cu steels at high fluences. After the irradiation, microstructure was observed and analyzed by Cs corrected TEM (STEM)-EDS (JELOL ARM200FC). By using the technique, simultaneous observation of Cu-rich precipitates of about 2~3 nm and dislocation loops were possible. In RIAM, Kyushu university, a tandem accelerator attached with two ion guns is also used for ion irradiation.
