Development of portable positron annihilation lifetime spectrometer and its in situ applications

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02742
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 34020:Analytical chemistry-related
• Research Institution: Chiba University
• Principal Investigator: Fujinami Masanori 千葉大学, 大学院工学研究院, 教授 (50311436)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 陽電子消滅 / 水素脆化 / 鉄 / ニッケル / 水素 / その場計測

Outline of Final Research Achievements

In the development of an in situ positron annihilation lifetime spectroscopy (PALS), I have proved that hydrogen-induced defects in pure iron are vacancy-hydrogen complexes by developing a PALS apparatus that enables measurement while hydrogen is charged, and suggested that hydrogen embrittlement is crucial because of their local densification. By utilizing a PALS apparatus capable of measuring on the order of minutes, it was also clarified that in pure Ni, unlike Fe, vacancies are formed only by hydrogen addition, and the relationship between the formation of vacancy clusters and the aging process of hydrogen desorption. Furthermore, it is suggested that the formation of vacancy-hydrogen complexes is also involved in the hydrogen embrittlement of Ni.

Free Research Field

分析化学

Academic Significance and Societal Importance of the Research Achievements

本研究では，水素添加しながら，あるいは延伸しながらその状態で陽電子消滅消滅が可能となり，材料の格子欠陥を調べることが可能となった。従来はそれらが空孔クラスターに成長した状態でしか観察できなかったが，これにより，不安定であった水素誘起欠陥を検出することに成功した。また，分オーダーでの陽電子消滅測定により，分オーダーで変化する空孔成長過程を直接観察することができた。これらは，従来知見を根底から覆すものであり，画期的である。今後，不安定な欠陥計測に開発装置は大きく寄与していくことが期待される。