Surface dislocation nucleation controlled deformation of Au nanowires
Surface dislocation nucleation controlled deformation of Au nanowires
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DOI：
10.1063/1.4902313
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发表时间：
2014-11-17
影响因子：
4
通讯作者：
Volkert, C. A.
中科院分区：
文献类型：
--
作者：
Roos, B.;Kapelle, B.;Volkert, C. A.
我们研究了高品质Au纳米线的变形下的拉伸和弯曲使用原位透射电子显微镜。缺陷演化过程中进行了研究：（1）拉伸变形的< 110 >取向，最初无缺陷，单晶纳米线的横截面宽度在30和300 nm之间，（2）弯曲变形的相同的线，和（3）拉伸变形的线含有连贯的孪晶界沿着其长度。我们观察到在拉伸条件下，在单晶线的孪晶和堆垛层错的形成，和存储后的单晶线弯曲和拉伸后的孪晶线的全位错。变形形态的应力状态依赖性和堆垛层错和孪晶的形成不是大块Au的特征，其中变形由位错相互作用控制。相反，我们属性的变形形态的表面成核的领导或尾随部分位错，这取决于施密德因素，移动通过和退出线产生堆垛层错或全位错滑移。诸如中性面或孪晶界的障碍物的存在阻碍了新成核位错的排出，并允许拖尾和前导部分位错联合收割机并作为全位错存储在线材中。我们推断，在纳米级Au样品中经常观察到的孪晶和堆垛层错不是直接的尺寸效应，而是从位错相互作用控制到位错成核控制变形的尺寸和障碍物依赖性转变的结果。(C)2014 AIP出版有限责任公司。
We investigate deformation in high quality Au nanowires under both tension and bending using in-situ transmission electron microscopy. Defect evolution is investigated during: (1) tensile deformation of < 110 > oriented, initially defect-free, single crystal nanowires with cross-sectional widths between 30 and 300 nm, (2) bending deformation of the same wires, and (3) tensile deformation of wires containing coherent twin boundaries along their lengths. We observe the formation of twins and stacking faults in the single crystal wires under tension, and storage of full dislocations after bending of single crystal wires and after tension of twinned wires. The stress state dependence of the deformation morphology and the formation of stacking faults and twins are not features of bulk Au, where deformation is controlled by dislocation interactions. Instead, we attribute the deformation morphologies to the surface nucleation of either leading or trailing partial dislocations, depending on the Schmid factors, which move through and exit the wires producing stacking faults or full dislocation slip. The presence of obstacles such as neutral planes or twin boundaries hinder the egress of the freshly nucleated dislocations and allow trailing and leading partial dislocations to combine and to be stored as full dislocations in the wires. We infer that the twins and stacking faults often observed in nanoscale Au specimens are not a direct size effect but the result of a size and obstacle dependent transition from dislocation interaction controlled to dislocation nucleation controlled deformation. (C) 2014 AIP Publishing LLC.