Zang Ketao, Mao Shengcheng, Cai Jixiang, Liu Yinong, Li Haixin, Hao Shijie, Jiang Daqiang, Cui Lishan
Beijing Key Lab of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing, 100124, China.
School of Mechanical and Chemical Engineering, The University of Western Australia, Crawley, WA 6009, Australia.
Sci Rep. 2015 Dec 2;5:17530. doi: 10.1038/srep17530.
Freestanding nanowires have been found to exhibit ultra-large elastic strains (4 to 7%) and ultra-high strengths, but exploiting their intrinsic superior mechanical properties in bulk forms has proven to be difficult. A recent study has demonstrated that ultra-large elastic strains of ~6% can be achieved in Nb nanowires embedded in a NiTi matrix, on the principle of lattice strain matching. To verify this hypothesis, this study investigated the elastic deformation behavior of a Nb nanowire embedded in NiTi matrix by means of in situ transmission electron microscopic measurement during tensile deformation. The experimental work revealed that ultra-large local elastic lattice strains of up to 8% are induced in the Nb nanowire in regions adjacent to stress-induced martensite domains in the NiTi matrix, whilst other parts of the nanowires exhibit much reduced lattice strains when adjacent to the untransformed austenite in the NiTi matrix. These observations provide a direct evidence of the proposed mechanism of lattice strain matching, thus a novel approach to designing nanocomposites of superior mechanical properties.
人们发现独立的纳米线表现出超大的弹性应变（4%至7%）和超高的强度，但事实证明，要在块状形式中利用其固有的优异机械性能却很困难。最近的一项研究表明，基于晶格应变匹配原理，嵌入镍钛（NiTi）基体中的铌（Nb）纳米线可实现约6%的超大弹性应变。为了验证这一假设，本研究通过拉伸变形过程中的原位透射电子显微镜测量，研究了嵌入NiTi基体中的Nb纳米线的弹性变形行为。实验工作表明，在NiTi基体中与应力诱发马氏体域相邻的区域，Nb纳米线中会产生高达8%的超大局部弹性晶格应变，而当纳米线的其他部分与NiTi基体中未转变的奥氏体相邻时，其晶格应变则会大幅降低。这些观察结果为所提出的晶格应变匹配机制提供了直接证据，从而为设计具有优异机械性能的纳米复合材料提供了一种新方法。
