Size Effects in the Torsion of Microscale Copper Wires: Experiment and Analysis

Our new paper entitled "Size Effects in the Torsion of Microscale Copper Wires: Experiment and Analysis", which has been accepted for publication in Scripta Materialia. As you know, there is a great deal of interest and excitement recently in understanding the mechanisms of size-scale effects in the plastic deformation of crystalline materials. Our manuscript provides the direct experimental evidence that strain gradient is still considerable in the torsion of microscale polycrystalline wires, wiping off the influence of external geometrical size and grain size. In our tests, we find significant size effects in both the plastic flow stress and initial yielding in torsion, while only slight size effects present in tension. The experimental result here is the first for complement to the tests performed by Fleck et al. (N.A. Fleck et al., Acta Metall. Mater. 42, 475 (1994). Cited times: more than 1200 times) to date. Our micro-torsion tests have higher resolution in the low strain region. Moreover, we have developed, for the first time, an automated micro-torsion test apparatus based on the torsion balance principle for obtaining the torque-twist data of microscale metallic wires straightforward. The experimental results are abundant, accurate and reproducible, which are also in excellent agreement with a theory of strain gradient plasticity. These findings may have implications in the basic mechanism for size-scale effects of crystalline materials in plasticity under un-uniform deformation.

You can download the paper from the link below:

http://www.sciencedirect.com/science/article/pii/S135964621100741X

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