ガンマ線誘起陽電子消滅法を用いた純鉄中の欠陥その場観察

In situ observation of defects in pure iron using gamma-ray-induced positron annihilation spectroscopy

薮内 敦*; 平出 哲也  ; 藤浪 真紀*; 淡路 亮*; 大島 永康*; 高井 健一*; 平 義隆*; 杉田 健人*

Yabuuchi, Atsushi*; Hirade, Tetsuya; Fujinami, Masanori*; Awaji, Ryo*; Oshima, Nagayasu*; Takai, Kenichi*; Taira, Yoshitaka*; Sugita, Kento*

UVSOR放射光施設でガンマ線誘起陽電子消滅分光法(GiPAS)技術を用いて、純鉄の引張変形中に形成される欠陥評価のため陽電子消滅寿命をその場測定した。ダンベル型の試験片を小型引張試験機に取り付け、ひずみ速度2.210/sで、公称ひずみ7以上まで延伸した。直径3mmの66MeVガンマ線パルスビームを引張変形中の試料中心部に照射して試料内で生成させた陽電子を用いて、純鉄試験片の引張変形中の陽電子寿命変化を観察した。従来報告されている変形後に取り外した状態での測定結果と異なり、特に変形初期の寿命変化が非常に少なく、その場測定の重要性が明らかとなった。

In situ measurements of positron annihilation lifetimes have been performed at the UVSOR synchrotron radiation facility to characterise defects formed during tensile deformation of pure iron using the gamma-ray induced positron annihilation spectroscopy (GiPAS) technique. A dumbbell-shaped specimen was attached to a small tensile tester and stretched to a nominal strain of 7 or more at a strain rate of 2.210/s. Positron lifetime changes during tensile deformation of a pure iron specimen were observed using positrons generated in the sample by irradiating the centre of the sample with a 66MeV gamma-ray pulse beam of 3mm in diameter. Unlike the results reported so far, the change in the positron lifetime, especially at the early deformation stage, was very small, making clear the importance of in-situ measurement.