中性子及び重イオン照射した原子炉圧力容器鋼モデル合金の3次元アトムプローブ観察

摘要

Microstructural characterization of reactor pressure vessel mode alloys irradiated by neutrons and Fe-ions was performed using three-dimensional atom probe tomography. Ultra-fine clusters of solute atoms, such as Cu, Ni, Mn and Si, with diameter in the range of 2-3 nm were formed at high number density in all the alloys. The cluster number density and the mean diameter of the alloys irradiated by Fe-ion were higher and smaller, respectively, than those of neutron-irradiated alloys. The clusters in Fe-ion irradiated alloys had less Cu and more Ni and Si content than those of neutron irradiated alloys. The increase in hardness of both irradiated alloys had almost linear correlation with the square root of the volume fraction of solute atom clusters.%軽水炉の原子炉圧力容器は運転中に中性子の照射を受けるrnことにより鋼材の材料特性が変化する，この現象は中性子照rn射脆化として知られており，運転期間の長期化に伴って脆化rn評価手法の高度化や脆化予測法の高精度化は重要な課題であrnる．鋼材の照射脆化を評価する脆化予測式は従来から各国でrn開発され利用されているが，近年では予測精度を向上させるrnため，照射脆化の機構論に基づく脆化予測式が開発さrnれ，規格として採用されるに至っている．