Microplasticity of copper thin films on silicon substrates |
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| Authors: | Y Nishino Y Ota T Kawazoe |
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| Institution: | 1. Department of Physics , School of Science, Beihang University , Beijing 100083, P. R. China;2. Theoretical Physics Division , Nankai Institute of Mathematics , Nankai University, Tianjin, 300071, P. R. China;3. Liuhui Center for Applied Mathematics , Tianjin, 300071, P. R. China jinshuo@buaa.edu.cn;5. Beijing Information Technology Institute , Beijing, 100101, P. R. China;6. Institute of Theoretical Physics , Northeast Normal University, Changchun 130024, P. R. China;7. Department of Physics , The City College of the City University of New York , New York, 10031, USA;8. Theoretical Physics Division , Nankai Institute of Mathematics , Nankai University, Tianjin, 300071, P. R. China;9. Liuhui Center for Applied Mathematics , Tianjin, 300071, P. R. China |
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| Abstract: | Internal friction in polycrystalline copper films 0.2-1.5 w m thick on silicon substrates has been measured as a function of strain amplitude. The internal friction in the films increases with increasing strain amplitude but at a value of the strain amplitude that is at least two orders of magnitude greater than the similar increase in bulk copper. Analysis of the amplitude-dependent internal friction provides the plastic strain of the order of 10 -9 as a function of effective stress on dislocation motion. Since the grain size is larger than the film thickness, the microflow stress at a constant level of plastic strain varies inversely with the film thickness. The film thickness effect in the microplastic range can be explained on the basis of a dislocation-bowing model. |
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