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Contactless measurement of electrical conductivity for bulk nanostructured silver prepared by high-pressure torsion: A study of the dissipation process of giant strain
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Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Graduate School of Engineering, Kyushu Institute of Technology, Kitakyushu 804-8550, Japan
Japan Synchrotron Radiation Research Institute (JASRI), Hyogo 679-5198, Japan
Faculty of Science, Fukuoka University, Fukuoka 814-0180, Japan
Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan, WPI, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
Department of Materials Science and Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan, WPI, International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, Fukuoka 819-0395, Japan
抄録
We measured the electrical conductivity of bulk nanostructured silver prepared by high-pressure torsion (HPT) in a contactless manner by observing the AC magnetic susceptibility resulting from the eddy current, so that we could quantitatively analyze the dissipation process of the residual strain with sufficient time resolution as a function of temperature T and initial shear strain γ. The HPT process was performed at room temperature under a pressure of 6 GPa for revolutions N = 0–5, and we targeted a wide range of residual shear strains. The contactless measurement without electrode preparation enabled us to investigate both the fast and slow dissipation processes of the residual strain with sufficient time resolution, so that a systematic study of these processes became possible. The changes in the electrical conductivity as a function of N at room temperature were indeed consistent with changes in the Vickers microhardness; furthermore, they were also related to changes in structural parameters such as the preferred orientation, the interplanar distance, and the crystallite size. The dissipation process at N = 1, corresponding to γ ≈ 30, was the largest and the fastest. For N = 5, corresponding to γ ≈ 140, we considered the effects of grain boundaries, as well as those of dislocations. The strain dissipation was quite slow below T = 290 K. According to the analytical results, it became successful to conduct the quantitative evaluation of the strain dissipation at arbitrary temperatures: For instance, the relaxation times at T = 280 and 260 K were estimated to be 3.6 and 37 days, respectively.
雑誌名
Journal of Applied Physics
巻
122
号
12
ページ
125105-1 - 125105-7
発行年
2017-09-26
出版者
AIP Publishing
ISSN
0021-8979
1089-7550
書誌レコードID
AA00693547
DOI
http://dx.doi.org/10.1063/1.4991430
権利
Copyright (c) 2017 Author(s).
The following article has been submitted to/accepted by Journal of Applied Physics. After it is published, it will be found at https://aip.scitation.org/journal/jap.
Contactless measurement of electrical conductivity for bulk nanostructured silver prepared by high-pressure torsion: A study of the dissipation process of giant strain
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