| Project/Area Number |
21K04627
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 26010:Metallic material properties-related
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| Research Institution | Chiba University |
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Principal Investigator |
Chiari Luca 千葉大学, 大学院工学研究院, 助教 (20794572)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2023: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2022: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2021: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Keywords | 水素脆化 / 空孔型欠陥 / 金属 / 陽電子消滅法 / その場測定 / 陽電子 |
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| Outline of Research at the Start |
The elucidation of the hydrogen embrittlement mechanism in hydrogen-susceptible metallic materials is a prerequisite for the safe use and development of structural materials, such as stainless steels, in the hydrogen transport and storage infrastructure in the advent of the upcoming hydrogen society.
In this research, we aim to detect and identify the primary atomic defects responsible for the hydrogen embrittlement process by devising and developing innovative approaches to positron annihilation spectroscopy, which is the only techniques for detecting atomic vacancies.
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| Outline of Annual Research Achievements |
The primary scope of this research is to determine the lattice defects responsible for hydrogen embrittlement in metallic materials, that are relevant in the hydrogen infrastructure, by in-situ measurements in a hydrogen environment and under application of tensile stress using newly developed experimental methods based on positron annihilation spectroscopy.
An experimental system was developed using a specific electrolytic cell that allows in-situ positron annihilation measurements under stress loading while charging hydrogen. Hydrogen-induced defects in pure iron strained under constant stress were successfully identified and their changes over time were tracked. In pure iron under conditions of high hydrogen susceptibility, the formation of vacancy-hydrogen complexes and their growth process into vacancy clusters by aging in air was observed for the first time.
In addition, using a high-intensity positron beam, the formation and time dynamics of hydrogen-induced defects in pure nickel was measured by high-speed positron lifetime measurements. Monovacancy-size defects were detected immediately after hydrogen charge, which indicates that vacancy-hydrogen complexes were formed just by hydrogen addition. Upon room temperature aging, the complexes gradually disappeared and vacancy clusters were formed, which increased in size. Hydrogen desorption from the complexes leads to mobile vacancies which agglomerate into increasingly larger clusters. These vacancies are thought to play an important role in the hydrogen embrittlement of nickel.
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