Experimental lower bounds on geometrically necessary dislocation density
Experimental lower bounds on geometrically necessary dislocation density
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DOI：
10.1016/j.ijplas.2010.03.009
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发表时间：
2010-08
影响因子：
9.8
通讯作者：
J. Kysar;Yuki Saito;M. S. Oztop;Dongyun Lee;W. T. Huh
中科院分区：
文献类型：
--
作者：
J. Kysar;Yuki Saito;M. S. Oztop;Dongyun Lee;W. T. Huh
用楔形压头压入镍单晶，使其产生具有三个有效平面应变滑移系的二维变形状态。使用定向成像显微镜（OIM）以3微米空间分辨率测量晶格的面内晶格旋转。从晶格旋转场计算Nye位错密度张量的所有非零分量。严格的解析表达式推导出的总几何必要位错（GND）密度的下限。证明了下界的存在唯一性，并确定了总GND密度在有效单个滑移系上的分配。在已知只有一个或两个有效滑移系被激活的情况下，下限解可简化为精确解。结果给出了洞察的活动滑移系统以及位错结构形成的镍晶体作为一个结果的楔形压痕。
A single nickel crystal is indented with a wedge indenter such that a two-dimensional deformation state with three effective plane strain slip systems is induced. The in-plane lattice rotation of the crystal lattice is measured with a three micrometer spatial resolution using Orientation Imaging Microscopy (OIM). All non-zero components of the Nye dislocation density tensor are calculated from the lattice rotation field. A rigorous analytical expression is derived for the lower bound of the total Geometrically Necessary Dislocation (GND) density. Existence and uniqueness of the lower bound are demonstrated, and the apportionment of the total GND density onto the effective individual slip systems is determined. The lower bound solution reduces to the exact solution under circumstances in which only one or two of the effective slip systems are known to have been activated. The results give insight into the active slip systems as well as the dislocation structures formed in the nickel crystal as a result of the wedge indentation.