Mechanical properties of micro-sized copper bending beams machined by the focused ion beam technique
Mechanical properties of micro-sized copper bending beams machined by the focused ion beam technique
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DOI：
10.1016/j.actamat.2005.05.036
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发表时间：
2005-09
期刊：
影响因子：
9.4
通讯作者：
C. Motz;T. Schöberl;R. Pippan
中科院分区：
文献类型：
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作者：
C. Motz;T. Schöberl;R. Pippan
采用聚焦离子束技术从{111}<011>取向的铜单晶制造了厚度t从7.5到1.0μm的微型弯曲梁。梁上装有纳米压头，并记录力与位移曲线。发现了强烈的尺寸效应，最薄梁的流变应力几乎达到 1 GPa。使用常见的应变梯度塑性方法来解释尺寸效应。然而，该模型无法解释流变应力对 t−1.14 的强烈依赖性。此外，还讨论了其他两种位错机制的组合：可用位错源的限制和梁中心的位错堆积。堆积应力对流变应力的贡献具有 t−1 依赖性，这与实验结果非常吻合。
Micro-sized bending beams with thicknesses, t, from 7.5 down to 1.0μm were fabricated with the focused ion beam technique from a copper single crystal with an {111}〈011〉 orientation. The beams were loaded with a nano-indenter and the force vs. displacement curves were recorded. A strong size effect was found where the flow stress reaches almost 1 GPa for the thinnest beams. A common strain gradient plasticity approach was used to explain the size effect. However, the strong t−1.14dependence of the flow stress could not be explained by this model. Additionally, the combination of two other dislocation mechanisms is discussed: the limitation of available dislocation sources and a dislocation pile-up at the beam centre. The contribution of the pile-up stress to the flow stress gives a t−1dependence, which is in good agreement with the experimental results.