低放射化マルテンサイト鋼における高濃度ヘリウムによる自己修復機能の発現

实验结果如下：1.氦效应：1)在423K下，当氦注入到600atppm以下时，马氏体钢不会发生脆化。注入后的退火可形成氦气泡，但未观察到氦诱导的晶间断裂。抑制氦脆的机制：由高密度位错、固溶体元素和大量析出物组成的马氏体组织捕获氦和空位，导致氦和空位在马氏体组织中广泛分布，阻止氦原子在晶界偏聚。辐照硬化回复延缓机制：氦在较高温度下稳定空位团簇，抑制V团簇分解。从而延缓了位错环和空位的相互湮灭。结论：氦捕获和辐照诱导的位错环的形成使硬化/软化的转变温度发生了移动。认为同时引入位移损伤和氦原子将改善材料的高温蠕变性能。

The experimental results were summarized as follows :1. Helium effects : 1) Martensitic steels does not suffer embrittlement by helium implantation up to 600 atppm at 423K. Post-implantation annealing results in the formation of helium bubbles but no helium-induced intergranular facture was observed.2. Mechanism of suppression of helium embritlement : Martensitic structure that consists of high density dislocation, solid solutioning elements and a number of precipitates traps helium and vacancies, which results in the wide distribution of helium and vacancies in the martensitic structure and prevent the helium atoms from segregation at grain bondaries.3. Mechanism of retardation of the recovery of irradiation hardening : Helium stabilizes vacancy cluster at higher temperature and suppress the decomposition of V-clusters. Consequently, mutual annihilation of dislocation loops and vacancies was retarded.Conclusion : Helium trapping and irradiation-induced dislocation loop formation shifts the transition temperature of hardening/softening. It is considered that the high temperature creep properties will be improved by the simultaneous introduction of the displacement damage and helium atoms.