| Autor: |
C D Gu, J S Lian, Q Jiang, W T Zheng |
| Předmět: |
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| Zdroj: |
Journal of Physics D: Applied Physics; Dec2007, Vol. 40 Issue 23, p7440-7446, 7p |
| Abstrakt: |
Two experimental techniques of nanoindentation and tensile testing were used at room temperature to investigate the strain rate sensitivity of an electrodeposited Ni with a mean grain size (d) of 20 nm, respectively. It was found that the nanocrystalline (nc) Ni possessed a higher strain rate sensitivity exponent (m) during nanoindentation than during tensile testing. Furthermore, a higher m was accompanied by a smaller activation volume (V). It is believed that the higher stress concentration could activate a shorter dislocation line length (L), which should be responsible for the higher m value during the nanoindentation. Based on a model of dislocation nucleation or bowing-out mechanism, the relationship between m and d for Ni and its alloys was investigated. In the end, a simple and straightforward equation relating m to d was proposed in aid of a simple assumption associating L with d, which implied that the enhanced m in nc Ni and its alloys with d > [?]6 nm should be due to the reduction of the dislocation line length. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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