2004 Fiscal Year Final Research Report Summary
Study of cascade damage effects detected by dynamic behavior of helium bubbles
| Project/Area Number |
14550654
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Shimane University |
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Principal Investigator |
ONO Kotaro Shimane University, Interdisciplinary Faculty of Science and Engineering, Professor, 総合理工学部, 教授 (40106795)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAMOTO Mitsutaka Shimane University, Interdisciplinary Faculty of Science and Engineering, Research Associate, 総合理工学部, 助手 (80379693)
ARAKAWA Kazuto Osaka University, UHVEM Center, Research Associate, 超高圧電子顕微鏡センター, 助手 (30294367)
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| Project Period (FY) |
2002 – 2004
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| Keywords | irradiation damage / helium bubble / electron microscopy / fusion reactor materials / Fe,Fe-9Cr alloy / Cu / lattice defect |
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| Research Abstract |
(1)Study of cascade damage effects detected by dynamic behavior of helium bubbles
High energy (100-400keV) self-ions were irradiated to Au,Cu,Si,Fe and Fe-Cr alloys specimens, to which helium bubbles were pre-introduced by irradiation with 10keV helium ions, and the dynamical behavior of the bubbles during the irradiation of high energy self-ions was studied by in-situ IVEM observation at Argonne National Laboratory. Helium bubbles can be used as a sensor for the cascade damage. It was found that most of the bubbles showed Brownian type-random motion even under the irradiation with high energy self-ions at high temperature, but their mobility was depressed. But, a small number of the bubble were accelerated. The depression and the acceleration of the bubbles should be caused by absorption of vacancies and by direct collision with ions, respectively. At middle temperatures, random motion of the bubble did not occur and an intermittent motion of helium bubbles along a dislocation loop was
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induced under the irradiation with high energy self-ions. Easy motion of helium bubbles along the dislocation lines at these temperatures was revealed. At lower temperatures, a sporadic motion in a limited region was revealed and this could be caused by direct collision with the cascade damage.
(2)Interaction of the bubble with dislocation and one-dimensional motion of dislocation loops
The interaction of helium bubbles with the dislocation was comparatively strong. It was revealed that the small bubble was thermally mobile along the dislocation line and the other directions. Bubbles can be used as a sensor of the strain field in the dislocation.
One-dimensional motion of the small interstitial type dislocation loops with the burgers vector 1/2<111> was studied during annealing or under the electron irradiation and it was revealed that the burgers vector changes to the other 1/2<111> or to <100> during the one-dimensional motion. At lower temperature, the number density of the loops increases in Fe-9Cr and it was suggested that one dimensional motion could be induced by their elastic interaction.
(3)TDS(Thermal Desorption Spectroscopy) of helium and its correlation with a change of the microstructure in Fe,Fe-9Cr
TDS spectra from helium irradiated Fe and Fe-9Cr and the correlated microstructure changes were studied. During a constant heating of the specimen up to 1000℃, five TDS peaks were observed. The peaks at lower temperatures are correlated with the dislocation trapping and ones at higher temperatures are correlated with the bubble motion to the surface and alpha-gamma phase transformation. Chromium segregated to the bubble or dislocation loops could shift the TDS peaks to higher temperature in Fe-9Cr alloy. Less
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