2005 Fiscal Year Final Research Report Summary
Experimental study on the obstacle strength factor to dislocation motion for the evaluation of radiation embrittlement of nuclear materials
| Project/Area Number |
14208057
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
MATSUI Hideki Tohoku University, Institute for Materials Research, Professor, 金属材料研究所, 教授 (50005980)
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| Co-Investigator(Kenkyū-buntansha) |
SATOH Yuhki Tohoku University, Institute for Materials Research, Associate Professor, 金属材料研究所, 助教授 (20211948)
FUKUMOTO Ken-ichi Fukui University, Faculty of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (30261506)
NITA Nobuyasu Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (30361174)
HATANO Takahiro Tokyo University, Earthquake Research Institute, Research Associate, 地震研究所, 助手 (20360414)
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| Project Period (FY) |
2002 – 2005
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| Keywords | TEM / radiation-induced embrittlement / dislocation / radiation hardening / in-situ TEM / molecular dynamics simulation / iron / helium bubble |
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| Research Abstract |
For the evaluation of lifetime of nuclear materials, it is important to examine the interaction of dislocations and obstacles. A number of researches have been devoted for this objective by observing obstacles by TEM, and from their size and number density, the induced hardening due to these obstacles was evaluated. Here, the important parameter is the obstacle strength factor that usually denoted as α, and was derived theoretically so far. However, the accuracy was usually not sufficient, and it was a customary in many cases that this parameter was treated as an adjustable parameter. The detection of obstacles, on the other hand, is very difficult in some cases, e.g. Cu-rich precipitates in RPVS with conventional TEM. Three-D Atom Probe can detect such tiny precipitates, but because of the limited size of sampling volume, it is difficult to obtain statistically significant value of the density and average size. In the present study, these tiny precipitates were detected as cusps on di
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slocation lines interacting with the precipitates. This is one of the major accomplishments of the technique developed here. Moreover, the obstacle strength parameter α can be measured directly from the apex angle of the cusp. Striking agreement was obtained between the hardening obtained from macroscopic mechanical test with that obtained from in situ TEM. This result shows the validity of the technique. MD simulation of the interaction process between dislocations and obstacles was carried out. The results were used to understand the microscopic process that cannot be examined by in situ TEM study. MD study further verified the method developed in this study.
Ultrasonic attenuation measurements under external stress and amplitude dependent internal friction measurements were also carried out. The former technique was developed in order to evaluate non-destructively radiation hardening. In situ TEM study, ultrasonic attenuation, and internal friction are all combined to yield a comprehensive view on the interaction of dislocations and obstacles. In the present study, it was demonstrated that ultrasonic attenuation measurement under external stress is a very promising method for non-destructive evaluation of radiation hardening. Less
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