体心立方金属Mo纳米线拉伸塑性行为的原位TEM观察
卢艳1，王立华1，邓青松1，胡忠武3，肖礼容1，向思思1，
张泽1，2*，韩晓东1*
（1.北京工业大学固体微结构与性能研究所，北京100124；2.浙江大学电子显微镜中心，材料科学与工程学系，浙江杭州310027；3. 西北有色金属研究研究，陕西西安710016）
摘 要：本文利用自创的热双金属片拉伸装置实现了在透射电镜中，对单晶Mo纳米线的原位拉伸实验。实验发现单晶Mo纳米线具有块体单晶材料2倍左右的塑性变形能力。观察发现变形过程中位错不断的形核产生、然后快速的运动并消失在纳米线表面是单晶Mo纳米线具有大塑性变形能力的一个重要原因。另外，利用选区电子衍射对拉伸断裂后的样品分析，发现拉伸后的纳米线的断口附近呈现多晶化。可以认为在高应变作用下，位错的滑移等因素导致单晶点阵局部扭转形成小角晶界，纳米线局部从单晶转变成多晶。
关键词：Mo纳米线；超大塑性；位错运动；体心立方
中图分类号：TB383；O711+.4；O77+2；TG115.21+5.3；TG115.5 文献标识码：A doi:10.3969/j.1000-6281.2014.04.001
In situ TEM observation of the plastic behavior of body-centered cubic metal Mo nanowires
LU Yan1, WANG Li-hua1, DENG Qing-song1, HU Zhong-wu3, XIAO Li-rong1, XIANG Si-si1,
ZHANG Ze1,2*,HAN Xiao-dong1*
(1.Institue of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124;2. Center of Electron Microscope, Zhejiang University, Hangzhou Zhejiang 310027;3. Northwest Institute for Non-ferrous Metal Research, Xi’an Shanxi 710016, China)
Abstract: Using a homemade bi-metallic extensor, the in-situ tensile experiments of Mo nanowire was conducted in a transmission electron microscope. Wedemonstratethat the Mo nanowire exhibit ultra-large plastic deformation ability, which is about twice as much as its bulk counterpart. The dislocation nucleation, motion and escaping are responsible for the ultra-large strain ability. In addition, the selected area electron diffraction patterns indicated deformation can lead to single-crystal to poly-crystal transformation near the fracture, which was rarely seen in previous. Under high stress, the local crystal lattice distortion, dislocation slip etc. lead to single-crystal to poly-crystal transformation.
Keywords: Mo nanowire; ultra-large plasticity; dislocations motion; body-centered cubic
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[1] Wang L H, Zhang Z, Han X D.In situ experimental mechanics of nanomaterials at the atomic scale [J]. NPG Asia Mater，2013, 5.
[2] Greer J R, Jeff Th M De Hosson. Plasticity in small-sized metallic systems: Intrinsic versus extrinsic size effect [J]. Prog Mater Sci，2011, 56: 654-724.
[3] Yue Y H, Liu P, Deng Q S, et al. Quantitative evidence of crosser toward partial dislocation mediated plasticity in copper single crystalline nanowires [J]. Nano Lett，2012, 12: 4045-4049.
[4] 岳永海, 周晓亮, 王立华, 等. Cu纳米线的制备及其力学性能的研究[J]. 电子显微学报, 2011, 3(3): 1-6.
[5] Uchic M D, Dimiduk D M, Florando J N, et al. Sample dimensions influence strength and crystal plasticity [J]. Science, 2004, 305(5686): 986-989.
[6] Greer J R, Nix W D. Nanoscale gold pillars strengthened through dislocation starvation [J]. Phy Rev B, 2006, 73(24): 245410.
[7] Greer J R, Weinberger C R, Cai W. Comparing the strength of fcc and bcc sub-micrometer pillars: compression experiments and dislocation dynamics simulations [J]. Mater Sci Eng A, 2008, 493: 21-25.
[8] Kiener D, Minor A M. Source truncation and exhaustion: insights from quantitative in situ TEM tensile testing [J]. Nano Lett, 2011, 11: 3816-3820.
[9] Oh S H, Legros M, Kiener D, et al. In situ observation of dislocation nucleation and escape in a submicrometre aluminium single crystal [J]. Nat Mater, 2009, 8: 95-100.
[10] Nix W D, Greer J R, Feng G, et al. Deformation at the nanometer and micrometer length scales: effects of strain gradients and dislocation starvation [J]. Thin Solid Films, 2007, 515: 3152-357.
[11] Norfleet D M, Dimiduk D M, Polasik S J, et al. Dislocation structures and their relationship to strength in deformed nickel microcrystals [J]. Acta Mater, 2008, 56 : 2988-3001.
[12] Benzerga A A. An analysis of exhaustion hardening in micron-scale plasticity [J]. Int J Plast, 2008, 24: 1128-1157.
[13] Rao S I, Dimiduk D M, Parthasarathy T A, et al. Athermal mechanisms of size-dependent crystal flow gleaned from three-dimensional discrete dislocation simulations [J]. Acta Mater, 2008, 56: 3245-3259.
[14] Parthasarathy T A, Rao S I, Dimiduk D M, et al. Contribution to size effect of yield strength from the stochastics of dislocation source lengths finite samples [J]. Scripta Mater, 2007, 56: 313-316.
[15] Rao S I, Dimiduk D M, Tang M, et al. Estimating the strength of single-ended dislocation sources in micron-sized single crystals [J]. Philos Mag A, 2007, 87: 4777-4794.
[16] El-Awady J A, Wen M, Ghoniem N M. The role of the weakest-link mechanism in controlling the plasticity of micropillars [J]. J Mech Phys Solids, 2009, 57: 32-50.
[17] Tian X G, Woo C. The movement of screw dislocations in tungsten [J]. Mater Sci Eng A, 2004, 369: 210-214.
[18] Vitek V. Core structure of screw dislocations in body-centred cubic metals: relation to symmetry and interatomic bonding [J]. Philos Mag, 2004, 84: 415-428.
[19] Weinberger C R, Cai W. Surface-controlled dislocation multiplication in metal micropillars [J]. Proc Natl Acad Sci, 2008, 105: 14304-14307.
[20] Kim J K, Jang D C, Greer J R. Tensile and compressive behavior of tungsten, molybdenum, tantalum and niobium at the nanoscale [J]. Acta Mater, 2010, 58: 2355-2363.
[21] Scheneider A S, Kaufmann D, Clark B G, et al. Correlation between critical temperature and strength of small-scale bcc pillars [J]. Phy Rev Lett，2009, 103: 105501.
[22] Schneider A S, Clark B G, Frick C P, et al. Effect of orientation and loading rate on compression behavior of small-scale Mo pillars[J]. Mater Sci Eng A，2009, 508: 241-246.
[23] Bei H, Shim S, Pharr G M, et al. Effects of pre-strain on the compressive stress-strain response of Mo-alloy single-crystal micropilars [J]. Acta Mater, 2008, 56 : 4762-4770.
[24] Huang L, Li Q J, Shan Z W, et al. A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum [J]. Nat Comm, 2011: 1557.
[25] 韩晓东, 刘攀, 张跃飞, 邓青松, 张泽. 透射电镜用非磁性双金属片驱动器[P]. 中国专利,200910086803.2. 2010.12.01.
[26] 韩晓东, 张泽. 原子点阵分辨率下的原位力学性能实验[J]. 电子显微学报, 2011, 29(3): 191212.
[27] Deng Q S, Cheng Y Q, Yue Y H, et al. Uniform tensile elongation in framed submicron metallic glass specimen in the limit of suppressed shear banding [J]. Acta Mater，2011, 59: 6511-6518.
[28] 黄孝瑛. 材料微观结构的电子显微学分析[M]. 北京:冶金工业出版社, 2008：75-78.
[29] Brinckmann S, Kim J Y, Greer J R. Fundamental differences in mechanical behavior between two types of crystals at the nanoscale [J]. Phy Rev Lett, 2008, 100(15) : 155502.
[30] Murayama M, Howe J M, Hidaka H, et al. Atomic-level observation of disclination dipoles in mechanically milled, nanocrystalline Fe [J]. Science, 2002, 295: 2433-2435.
[31] Liu P, Mao S C, Wang L H, et al. Direct dynamic atomic mechanisms of strain-induced grain rotation in nanocrystalline, textured, columnar-structured thin gold films [J]. Scripta Mater，2011, 64: 343-346.
