Size dependence of the plane-strain response of single-crystal Al to indentation by diamond wedges
Size dependence of the plane-strain response of single-crystal Al to indentation by diamond wedges
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DOI：
10.1016/j.actamat.2012.05.021
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发表时间：
2012-07
期刊：
影响因子：
9.4
通讯作者：
Ke Chen;W. Meng;G. Sinclair
中科院分区：
文献类型：
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作者：
Ke Chen;W. Meng;G. Sinclair
在室温下，用一系列棱柱形金刚石压头对单晶铝试样进行了压痕。压头具有三角形或楔形横截面，并且相对较长，从而引起二维（2-D）平面应变响应。使用了不同的楔角。对于每个楔形压头，在不同的载荷下进行仪表压痕。从每个楔形压痕实验的响应分析清楚地揭示了存在的尺寸效应，表现在一个不断增加的预计接触压力的接触尺寸从微米到亚微米级下降。当压痕响应从2-D楔形压头与不同的夹角进行了比较，数据表明，这种压痕尺寸效应依赖于楔角。这种依赖性进行了分析，并与现有的模型压痕的基础上的几何必要的位错的概念。虽然模型预测的特征长度对所包括的楔角的依赖性似乎与当前的实验是一致的，模型估计的特征长度的大小显着超过从实验中推导出的值。本研究结果提供了新的实验证据的尺寸依赖的压痕响应在平面应变的几何形状。
A single-crystal Al specimen was indented at room temperature with a series of prismatic diamond indenters. The indenters had triangular or wedge-shaped cross-sections and were relatively long, thus inducing a two-dimensional (2-D) plane-strain response. Different included wedge angles were used. For each wedge indenter, instrumented indentations were carried out at varying loads. Analysis of the response from each wedge indentation experiment clearly revealed the presence of a size effect, manifested in an increasing projected contact pressure as the contact dimensions decreased from micron to submicron scales. When indentation responses from 2-D wedge indenters with different included angles were compared, the data showed evidence that this indentation size effect depended on the included wedge angle. This dependence was analyzed and compared to existing models of indentation based on the concept of geometrically necessary dislocations. While the model prediction of the dependence of the characteristic length on the included wedge angle appears to be consistent with current experiments, the model estimate of the magnitude of the characteristic length significantly exceeds the value deduced from experimentation. The present results offer new experimental evidence of size-dependent indentation response in plane-strain geometries.