Helical Domain Patterns in Tube Configurations: Effect of Geometry Length Scales

2011 ◽  
Vol 172-174 ◽  
pp. 1090-1095 ◽  
Author(s):  
R.H. Zhou ◽  
Qing Ping Sun
Keyword(s):  
Strain Energy ◽  
Optical Measurement ◽  
Strong Support ◽  
Martensite Phase ◽  
Helical Domain ◽  
Self Organized ◽  
Bending Strain ◽  
Strain Martensite ◽  
Tube Geometry

Superelastic NiTi polycrystalline tubes, when subjected to quasi-static stretching, transform from an initial austenite phase to a high-strain martensite phase by the formation and growth of a macroscopic self-organized helical domain as deformation progresses. This paper performed an experimental study on the effects of the externally applied stretching and tube geometry (length L, wall-thickness h and tube radius R) on the martensitic helical domains in the tubes under very slow (isothermal) stretching. The evolution of the helical domains with the applied strain in different tube geometries are quantified by in-situ optical measurement. We demonstrate that the shape of the self-organized helical domain and its evolution are governed by the competition between bending strain energy and domain front energy in minimizing the total energy of the tube system. The former favors a long slim helical domain, while the latter favors a short fat helical domain. The experimental results provide a strong support to the recently developed theoretical relationship.

Optical Measurement Technique of Water Contents in Polymer Membrane for PEFCs

2005 ◽  
Vol 3 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Kazuyoshi Fushinobu ◽  
Kenji Shimizu ◽  
Nariaki Miki ◽  
Ken Okazaki
Keyword(s):  
Water Content ◽  
Polymer Electrolyte ◽  
Optical Measurement ◽  
Polymer Electrolyte Membrane ◽  
Calibration Procedure ◽  
Polymer Electrolyte Fuel Cells ◽  
Infrared Light ◽  
Electrolyte Membrane ◽  
Transient Measurement

The feasibility of an optical technique is examined for the measurement of the membrane water content in polymer electrolyte fuel cells (PEFCs). Transmission of the infrared light of 1.92 μm wavelength is used to measure the water content in the polymer electrolyte membrane. A calibration procedure is examined, and the technique is applied for the transient measurement of a Nafion membrane that gives the value of water diffusion coefficient, consistent with previous reports. The technique is then applied to an operating PEFC to show its applicability for in situ measurement.

scholarly journals In situ wide-field visualization of palladium hydrogenation

2020 ◽  
Author(s):  
Chongjun Jin ◽  
Nicholas Fang ◽  
Xiaoyi She ◽  
Huifeng Du ◽  
Yang Shen ◽  
...  
Keyword(s):  
Real Time ◽  
Hydrogen Diffusion ◽  
Fast Response ◽  
Wide Field ◽  
Ion Diffusion ◽  
Optical Contrast ◽  
Self Organized ◽  
Transmission Electron ◽  
Kinetics Of

Abstract Visualizing hydrogenation processes in metals in real-time is important to various hydrogen-involved applications. However, observing hydrogen diffusion was limited by transmission electron microscopy, and the kinetics of hydrogenation in the interior of the metals was not reported. Here we proposed an optical microscopy-based visualization of palladium hydrogenation from diffusion surface to the interior by introducing a fast-response mechanical platform that transforms the hydrogen diffusion into self-organized ordered wrinkles with sharp optical contrast. This platform is an Au/Pd double layer on elastomer which results in directional hydrogenation from sidewall to the interior. The kinetics of hydrogenation in the interior of the palladium along the diffusion direction was monitored in real-time. This platform will enable in-situ visualization of atom/ion diffusion on metals that are crucial in energy storage and hydrogen detection.

In-Situ Self-Organized Anode Interlayer Enables Organic Solar Cells with Simultaneously Simplified Processing and Greatly Improved Efficiency to 17.8%

Nano Energy ◽  
2021 ◽  
pp. 106814
Author(s):  
Jianhua Jing ◽  
Sheng Dong ◽  
Kai Zhang ◽  
Boming Xie ◽  
Jiabin Zhang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Self Organized

scholarly journals Droplet clusters: nature-inspired biological reactors and aerosols

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190121 ◽  
Author(s):  
Alexander A. Fedorets ◽  
Edward Bormashenko ◽  
Leonid A. Dombrovsky ◽  
Michael Nosonovsky
Keyword(s):  
Polymer Surface ◽  
Water Layer ◽  
Breath Figures ◽  
Self Organized ◽  
Droplet Cluster ◽  
Active Research ◽  
Living Nature ◽  
And Migration ◽  
Hexagonally Ordered

Condensed microdroplets play a prominent role in living nature, participating in various phenomena, from water harvesting by plants and insects to microorganism migration in bioaerosols. Microdroplets may also form regular self-organized patterns, such as the hexagonally ordered breath figures on a solid surface or levitating monolayer droplet clusters over a locally heated water layer. While the breath figures have been studied since the nineteenth century, they have found a recent application in polymer surface micropatterning (e.g. for superhydrophobicity). Droplet clusters were discovered in 2004, and they are the subject of active research. Methods to control and stabilize droplet clusters make them suitable for the in situ analysis of bioaerosols. Studying life in bioaerosols is important for understanding microorganism origins and migration; however, direct observation with traditional methods has not been possible. We report preliminary results on direct in situ observation of microorganisms in droplet clusters. We also present a newly observed transition between the hexagonally ordered and chain-like states of a droplet cluster. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

An In Situ Observation of Slip Deformation in a Compressed Ti-Mo-Al Single Crystal

2018 ◽  
Vol 941 ◽  
pp. 1463-1467
Author(s):  
Ryotaro Hara ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
Hideki Hosoda
Keyword(s):  
Martensitic Transformation ◽  
Slip System ◽  
Single Crystal ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Martensite Phase ◽  
Slip Direction ◽  
Β Phase ◽  
Slip Deformation

The stress-induced martensitic transformation and slip deformation behavior were investigated by the compression test with anin-situobservation in a Ti-6Mo-10Al (mol %) alloy single crystal. Owing to the stress-induced martensitic transformation from the parent β phase to the α′′ martensite phase, the single crystal of α′′ martensite without internal twinnings was successfully obtained at room temperature. By further compression, the slip deformation occurred in the single crystal of α′′ martensite. The operated slip system in the α′′ martensite was analyzed by the two face trace analyses, and the slip direction was determined to be []o.

The crystallization and growth of AlB2 single crystal flakes in aluminum

1998 ◽  
Vol 13 (12) ◽  
pp. 3485-3498 ◽  
Author(s):  
C. Deppisch ◽  
G. Liu ◽  
A. Hall ◽  
Y. Xu ◽  
A. Zangvil ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Strain Energy ◽  
Misfit Strain ◽  
Homogeneous Distribution ◽  
Temperature Growth ◽  
High Temperature Heat Treatment ◽  
Temperature Heat ◽  
Peritectic Transition ◽  
Temperature Heat Treatment

An in situ high temperature heat treatment was used to investigate the crystallization and growth behavior of AlB2 flakes in aluminum. Aluminum samples containing 1.8% boron were heated above the liquidus and then rapidly cooled through the Al(L) + AlB12 region to avoid the formation of AlB12 crystals. Subsequently, a homogeneous distribution of high aspect ratio AlB2 flakes crystallized upon holding below the peritectic transition temperature. Growth rate in the (a) and (c) dimensions increased during elevated hold temperatures below the peritectic transition temperature. Surprisingly, faster cooling rates from above the liquidus to room temperature resulted in thinner, wider flakes. Similar to graphite this phenomenon is believed to result from a need to accommodate a changing misfit strain energy between the solidifying aluminum and the growing AlB2 flakes.

Evaluation of Prestressing with a Shape Memory Alloy

1997 ◽  
Vol 503 ◽  
Author(s):  
Arup K. Maji
Keyword(s):  
Shape Memory ◽  
Prestressed Concrete ◽  
Strain Energy ◽  
Event Rate ◽  
Martensite Phase ◽  
Nickel Titanium ◽  
Prestress Losses ◽  
Higher Temperature ◽  
Prestressed Concrete Bridge ◽  
Niti Wires

ABSTRACTThe paper addresses the possibility of using shape-memory effect in Nitinol (Nickel-Titanium) alloy to remedy prestress losses in aging concrete beams. Straight annealed NiTi in the low temperature martensite phase can undergo large plastic deformations. This deformation and strain energy is recoverable when the material transforms to the higher temperature (about 55° C) austentite phase. This phenomena can be exploited to induce curvature, hence prestressing, by embedding NiTi wires and ropes in a structural member. Depending on the type of wire used its actuation effect can be reversed as necessary, creating the possibility of a smart prestressed concrete bridge of the future.Materials aspect studied in this project include the bond between NiTi wires and the host composite material, through mechanical testing and microscopy. An evaluation of the phase transformation is conducted using Acoustic Emission (AE) technology. AE event rate, locations and characteristics were evaluated during the actuation process.

In Situ TEM Observation of Phase Transformation for Bio-Medical Shape Memory TiNbSn Alloy

2010 ◽  
Vol 152-153 ◽  
pp. 1755-1758
Author(s):  
Yan Li ◽  
Jie Qi ◽  
Rui Rui Fan ◽  
Chuan Xin Zhai ◽  
Chun Hua Xu
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Shape Memory ◽  
Martensite Phase ◽  
Unit Cell ◽  
Niti Shape Memory Alloy ◽  
Transformation Mechanism ◽  
Cell Parameters ◽  
Β Phase

TiNbSn alloy has high specific strength, low modulus of elasticity, excellent corrosion resistance, no side effects, such as toxic and exhibits shape memory effects after appropriate technical processing. This alloy may substitute as NiTi shape memory alloy to become the new generation of biological materials. It has been reported the studies of this alloy, such as the component and proportion, processing technology, mechanical properties and corrosion resistance. Based on the previous research, the bio-metal material, Ti-10Nb-5Sn alloy was heated and cooled repeatedly in a heater system located in TEM chamber and, at the same time, was observed in situ using a high resolution transmission electron microscope to study the memory property of the alloy and the mechanism of the transformation between austenite β and martensite phase. The results show that, during heating stage from 295K to 400K, the martensite began to dissolve at 355K, and the martensite disappeared completely at 385K, meanwhile, the austenite was created. During cooling stage from 400K to 295K, the martensite begins to take shape at 353K and the transformation was completed at 333K. The alloy can memory the room and high temperature structures, showing two-way memory functions. The high-temperature austenite of Ti-10Nb-5Sn alloy shows body-centered cubic β phase with the unit cell parameter a=0.3283nm; the martensite at room temperature shows orthorhombic NbTi4 phase (M) with the unit cell parameters a=0.3152nm, b=0.4854nm, c=0.4642nm. The orientation relationship between M phase and β phase is , , , , and . The crystal plane , as the habit plane, transforms into during the transformation from β to M phases. The martensite transformation mechanism is that the and transform to and through the tiny migration of atoms.

Texture Evolution in Cu Films and Lines

2007 ◽  
Vol 990 ◽  
Author(s):  
Chia-Jeng Chung ◽  
David Field ◽  
No-Jin Park ◽  
Christy Woo
Keyword(s):  
Grain Growth ◽  
Strain Energy ◽  
Texture Evolution ◽  
Growth Conditions ◽  
Geometric Constraints ◽  
In Situ Observation ◽  
Processing Conditions ◽  
Cu Films ◽  
Unique Character

ABSTRACTGrain growth in polycrystalline films is controlled by the energetics of the surface, interface and grain boundaries as well as strain energy. The unique character of damascene lines fabricated from electroplated Cu films introduces the additional considerations of bath chemistry and geometric constraints. The moderate stacking fault energy of Cu allows for the development of a substantial twin fraction for certain growth conditions. This paper discusses in-situ observation of grain growth in Cu films and lines under various processing conditions. It is shown that for thicker films and for structures constrained within damascene trenches the energetics of twin boundary formation play a large role in texture development of these structures.

UHV-TEM/REM Study of Palladium Silicide Islands Grown on Silicon (111) 7×7 Surface

2001 ◽  
Vol 7 (S2) ◽  
pp. 318-319
Author(s):  
M. Takeguchi ◽  
K. Mitsuishi ◽  
J. Liu ◽  
Q. Zhang ◽  
M. Tanaka ◽  
...  
Keyword(s):  
Electron Beam ◽  
Functional Materials ◽  
Side Surface ◽  
Beam Direction ◽  
Self Organized ◽  
Reflection Electron Microscopy ◽  
Rectangular Specimen ◽  
Palladium Silicide ◽  
Transmission And Reflection

The growth of self-organized nanoislands and nanowires on a substrate has been extensively studied with a view to fabricating the new functional materials and advanced electric devices. in the present work, Pd silicide islands and wires grown on Si (111) 7x77×7surface were observed in situ by ultrahigh vacuum transmission and reflection electron microscopy (UHV-TEM/REM). Pd was deposited on Si (111) 7×7 surface at about 700 K using an electron beam evaporator attached to the column of a UHV microscope. Two kinds of specimens were prepared: a <111> oriented rectangular specimen with a thin area, whose (111) top surface was observed by plan viewed TEM, and a <110> oriented bulk rectangular specimen, whose (111) side surface was observed by REMFigure la shows a REM image of Si (111) 7×7 surface. An incident electron beam is directed from the top to the bottom of the figure, which is foreshortened in the beam direction.

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