Strain-Induced Structural Evolution and High Robustness in Single Crystalline Fivefold Twinned Cu@C Coaxial Nanowires

2014 ◽  
Vol 1033-1034 ◽  
pp. 1213-1219
Author(s):  
Yu Xin Zhao ◽  
Ying Zhang ◽  
Yan Peng Li ◽  
Zi Feng Yan
Keyword(s):  
Structural Evolution ◽  
Deformation Mechanisms ◽  
Facile Hydrothermal Method ◽  
Single Crystalline ◽  
Ultrahigh Strength ◽  
Tension Tests ◽  
Transmission Electron ◽  
Good Crystalline Quality ◽  
Mechanical Performances

Here, we developed single crystalline Cu@C nanowires with fivefold twinned structure via a facile hydrothermal method. In situ uniaxial tension tests of these NWs performed in transmission electron microscopy chamber reveal the ultrahigh strength (as much as 6.2 GPa) accompanied by favorable ductility (elongation>15%). The excellent performances benefit from nanoscale dimensions, unique penta-twinned geometry and good crystalline quality with protection of carbon shells. The study also provides direct experimental evidence for the theoretical modeling on the deformation mechanisms of metallic nanowires that have appeared in recent years. We expect that these findings can open a new window for applications in micro-or nanoelectromechanical devices where superior mechanical performances are desirable.

scholarly journals Imaging the Polymorphic Transformation in a Single Cu6Sn5 Grain in a Solder Joint

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2229 ◽  
Author(s):  
Flora Somidin ◽  
Hiroshi Maeno ◽  
Xuan Tran ◽  
Stuart D. McDonald ◽  
Mohd Mohd Salleh ◽  
...  
Keyword(s):  
Solder Joint ◽  
Polymorphic Transformation ◽  
Structural Evolution ◽  
Real Space ◽  
Transformation Behavior ◽  
New Approach ◽  
Transmission Electron ◽  
Contrast Pattern ◽  
In Situ Observations

In-situ observations of the polymorphic transformation in a single targeted Cu6Sn5 grain constrained between Sn-0.7 wt % Cu solder and Cu-Cu3Sn phases and the associated structural evolution during a solid-state thermal cycle were achieved via a high-voltage transmission electron microscope (HV-TEM) technique. Here, we show that the monoclinic η′-Cu6Sn5 superlattice reflections appear in the hexagonal η-Cu6Sn5 diffraction pattern upon cooling to isothermal 140 °C from 210 °C. The in-situ real space imaging shows that the η′-Cu6Sn5 contrast pattern is initiated at the grain boundary. This method demonstrates a new approach for further understanding the polymorphic transformation behavior on a real solder joint.

scholarly journals Anti-twinning in nanoscale tungsten

2020 ◽  
Vol 6 (23) ◽  
pp. eaay2792
Author(s):  
Jiangwei Wang ◽  
Zhi Zeng ◽  
Minru Wen ◽  
Qiannan Wang ◽  
Dengke Chen ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Shear Displacement ◽  
Atomic Scale ◽  
Deformation Mechanisms ◽  
Body Centered Cubic ◽  
Plastic Shear ◽  
Transmission Electron ◽  
20 Nm ◽  
Scale Shear

Nanomaterials often surprise us with unexpected phenomena. Here, we report a discovery of the anti-twinning deformation, previously thought impossible, in nanoscale body-centered cubic (BCC) tungsten crystals. By conducting in situ transmission electron microscopy nanomechanical testing, we observed the nucleation and growth of anti-twins in tungsten nanowires with diameters less than about 20 nm. During anti-twinning, a shear displacement of 1/3〈111〉 occurs on every successive {112} plane, in contrast to an opposite shear displacement of 1/6〈1¯1¯1¯〉 by ordinary twinning. This asymmetry in the atomic-scale shear pathway leads to a much higher resistance to anti-twinning than ordinary twinning. However, anti-twinning can become active in nanosized BCC crystals under ultrahigh stresses, due to the limited number of plastic shear carriers in small crystal volumes. Our finding of the anti-twinning phenomenon has implications for harnessing unconventional deformation mechanisms to achieve high mechanical preformation by nanomaterials.

scholarly journals Preparation and Characterization of Ni(OH)2and NiO Mesoporous Nanosheets

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Changyu Li ◽  
Shouxin Liu
Keyword(s):  
Decomposition Method ◽  
Mixed Solution ◽  
X Ray Diffraction ◽  
Facile Hydrothermal Method ◽  
Sodium Dodecylbenzenesulfonate ◽  
Single Crystalline ◽  
X Ray ◽  
Thermal Decomposition Method ◽  
Transmission Electron

Mesoporous nanosheets of single-crystallineβ-nickel hydroxide (β-Ni(OH)2) were successfully synthesized via a facile hydrothermal method using Ni(NO3)2 · 6H2O as precursor in a mixed solution of sodium hydroxide (NaOH) and sodium dodecylbenzenesulfonate (SDBS). Single-crystalline nickel oxide (NiO) mesoporous nanosheets can be obtained through a thermal decomposition method usingβ-Ni(OH)2mesoporous nanosheets as precursor. The influences of SDBS and hydrothermal treatment were carefully investigated; the results showed that they played important roles in the formation ofβ-Ni(OH)2mesoporous nanosheets. The as-obtainedβ-Ni(OH)2and NiO were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravity-differential thermal analysis (TG-DTA), and specific surface area, and pore size test.

In Situ Transmission Electron Microscopy Investigation of the Deformation Behavior of Cu with Nanoscale Twins

2009 ◽  
Vol 633-634 ◽  
pp. 63-72 ◽  
Author(s):  
Y. B. Wang ◽  
M.L. Sui
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Deformation Behavior ◽  
Emission Sources ◽  
Dislocation Emission ◽  
Ultrahigh Strength ◽  
Transmission Electron ◽  
Microscopy Investigation ◽  
Electron Microscopy Investigation

This paper reviews our recent studies on the effect of twin boundary (TB) on the deformation behavior in Cu with nanoscale growth twins. In situ straining transmission electron microscopy investigations on TB migration, TBs and twin ends acting as dislocation emission sources, and the interactions between dislocations and TBs are highlighted. Results provide some useful understanding of why Cu with nanoscale twins leads to a combination of ultrahigh strength and high ductility.

scholarly journals Decorrelated Dislocation Movement in the γ-Matrix Channels of a Ni-Based Superalloy: Experiment and Dislocation Dynamics Simulation

2011 ◽  
Vol 278 ◽  
pp. 13-18
Author(s):  
Florence Pettinari-Sturmel ◽  
Joël Douin ◽  
Didier Locq ◽  
Pierre Caron ◽  
Armand Coujou
Keyword(s):  
Partial Dislocation ◽  
Dislocation Dynamics ◽  
Dynamics Simulation ◽  
Deformation Mechanisms ◽  
Narrow Channels ◽  
Microscopic Scale ◽  
Transmission Electron ◽  
Dislocation Movement ◽  
Low Strain Rate

The mechanical behavior of the polycrystalline NR3 Ni-based superalloy has been investigated at the microscopic scale. The elementary deformation mechanisms have been analyzed using transmission electron microscope observations as well as in situ straining experiments. Under low stress and relatively low strain rate conditions, a large variety of shearing micromechanisms has been observed depending on the local microstructure and the local effective stress. The influence of the smallest precipitates on the creep behavior has been enlightened: they induce narrow channels which act as obstacle for the movement of the dislocations. In the case of the narrowest channel, the deformation can operate by the propagation of Shockley dislocations or else, by the only propagation of the leading partial resulting from the partial dislocation decorrelation. The occurrence of the observed micromechanisms has been quantitatively analyzed using a nodal dislocation dynamics simulation.

scholarly journals Applications of in situ electron microscopy in oxygen electrocatalysis

2022 ◽  
Author(s):  
Zhi-Peng Wu ◽  
Hui Zhang ◽  
Cailing Chen ◽  
Guanxing Li ◽  
Yu Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Degradation Mechanism ◽  
Structural Evolution ◽  
Reduction Reaction ◽  
Future Research ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
In Situ Electron Microscopy

Oxygen electrocatalysis involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a vital role in cutting-edge energy conversion and storage technologies. In situ studies of the evolution of catalysts during oxygen electrocatalysis can provide important insights into their structure - activity relationships and stabilities under working conditions. Among the various in situ characterization tools available, in situ electron microscopy has the unique ability to perform structural and compositional analyzes with high spatial resolution. In this review, we present the latest developments in in situ and quasi-in situ electron microscopic techniques, including identical location electron microscopy, in situ liquid cell (scanning) transmission electron microscopy and in situ environmental transmission electron microscopy, and elaborate their applications in the ORR and OER. Our discussion centers on the degradation mechanism, structural evolution and structure - performance correlations of electrocatalysts. Finally, we summarize the earlier discussions and share our perspectives on the current challenges and future research directions of using in situ electron microscopy to explore oxygen electrocatalysis and related processes.

scholarly journals In Situ Study of Deformation Mechanisms in Sputtered Free-Standing Nanocrystalline Nickel Films

2004 ◽  
Vol 19 (4) ◽  
pp. 1029-1037 ◽  
Author(s):  
R. Mitra ◽  
A. Chiou ◽  
J.R. Weertman
Keyword(s):  
Deformation Mechanisms ◽  
Free Standing ◽  
Ample Evidence ◽  
Nickel Films ◽  
Major Mechanism ◽  
Transmission Electron ◽  
Grain Size Distributions ◽  
Bulk Nanocrystalline ◽  
Parallel Arrays

Nickel films of 1.5–10-μm thickness, produced by dc magnetron sputtering and with disperse grain size distributions peaking in the 30–60-nm range, were subject to in situ tensile straining in a transmission electron microscope. The deformation was stopped frequently, while keeping the load applied, for transmission electron microscopy observation of the internal structure. Contrast changes occurred in many of the grains between strain increments. Ample evidence was seen of dislocation activity, which appears to be the major mechanism for deformation of the samples. Dislocations were seen in grains as small as 20 nm. Parallel arrays of roughly equally spaced dislocations were observed, spaced about 5–10-nm apart. Intergranular nanovoids were found to form and grow with accompanying strain relief in neighboring grains. The results of the current study are generally consistent with previous in situ investigations and contribute to the understanding of deformation mechanisms in free-standing thin films, which may differ somewhat from those in bulk nanocrystalline materials or in films attached to a substrate.

Large Scale Synthesis of Dendritic CdS Nanostrucutres

2013 ◽  
Vol 643 ◽  
pp. 186-190
Author(s):  
Meng Le Sun ◽  
Yan Xin Yang
Keyword(s):  
Large Scale ◽  
Raw Materials ◽  
High Yield ◽  
Facile Hydrothermal Method ◽  
Single Crystalline ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Cds Nanostructures ◽  
First Time

Single crystalline CdS dendrites were successfully synthesized in high yield by a simple and facile hydrothermal method. The allyl thiourea and CdCl2•5H2O were used as raw materials for the synthesis of dendritic CdS nanostructures for the first time. The as-prepared products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscope and selected area electron diffraction. The results demonstrate that the petal in an individual dendritic CdS nanoarchitecture is single crystalline and prefers growth along the [101] direction. The reaction parameters affected the CdS morphology were investigated systematically. It is found that the morphology of the samples are strongly dependent on the cadmium source, sulfide source, the reaction time and the solvent, the temperature has no effect on the morphology of the products. The possible mechanism was proposed for the formation of dendritic CdS nanostructures

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