Twin microstructure dependent mechanical response in Ni–Mn–Ga single crystals

2010 ◽  
Vol 96 (13) ◽  
pp. 131903 ◽  
Author(s):  
Ladislav Straka ◽  
Natalyia Lanska ◽  
Kari Ullakko ◽  
Alexei Sozinov
Keyword(s):  
Single Crystals ◽  
Mechanical Response

Dielectric and Mechanical Response of Ice Ih Single Crystals and Its Interpretation

1972 ◽  
Vol 57 (6) ◽  
pp. 2560-2571 ◽  
Author(s):  
A. von Hippel ◽  
R. Mykolajewycz ◽  
A. H. Runck ◽  
W. B. Westphal
Keyword(s):  
Single Crystals ◽  
Mechanical Response

scholarly journals Time-Dependent Mechanical Response of APbX3 (A = Cs, CH3 NH3 ; X = I, Br) Single Crystals

2017 ◽  
Vol 29 (24) ◽  
pp. 1606556 ◽  
Author(s):  
Marcos A. Reyes-Martinez ◽  
Ahmed L. Abdelhady ◽  
Makhsud I. Saidaminov ◽  
Duck Young Chung ◽  
Osman M. Bakr ◽  
...  
Keyword(s):  
Single Crystals ◽  
Mechanical Response ◽  
Time Dependent

scholarly journals Photosalient Effect: Dramatic conversion of light into mechanical motion

2014 ◽  
Vol 70 (a1) ◽  
pp. C1224-C1224
Author(s):  
Subash Sahoo ◽  
Pance Naumov
Keyword(s):  
Single Crystals ◽  
Flexible Electronics ◽  
Mechanical Response ◽  
Mechanical Energy ◽  
Small Scale ◽  
Molecular Rotor ◽  
Mechanical Motion ◽  
Molecular Actuators ◽  
Liquid Crystal Elastomers ◽  
External Stimuli

Materials showing mechanical response in presence of external stimuli are of relevance for the design of nanoscale actuating devices for a variety of small-scale applications including actuators, flexible electronics, artificial muscles, and others. In recent years, molecular actuators[1] (molecular rotor, elevator, etc.) and several macroscopic systems based on liquid-crystal elastomers, gels, and other polymers[2] have been developed. The most recent efforts are aimed at achieving rapid, reversible, maximum and fatigueless response with single crystals which display optimum coupling between light and the mechanical energy. When exposed to light, certain single crystals can jump up to thousands times their own size. The term "photosalient" was introduced recently to describe this phenomenon.[3] The photosalient effect in the motile crystals represents a direct and visually impressive demonstration of the conversion of light into mechanical motion through a photochemical reaction on a macroscopic scale, which sets the platform for the design of fast biomimetic and technomimetic actuating materials that can mimic animal motions, dynamics of macromolecules, or dynamic technical elements, in the future. In this presentation, we will describe the mechanical response from photosalient single crystals that undergo photoinduced linkage isomerization. To understand the mechanistic details, the mechanism of the process was studied by X-ray photodiffraction, kinematic analysis, IR spectroscopy and mechanical characterization. In contrast to many other solid-state transformations that involve nucleation and propagation of the reaction interface, in this system the reaction proceeds homogeneously whereupon solid solutions form without apparent phase separation.

Effects of Deviation from Stoichiometry on Deformation Behavior of Hard-Oriented NiAl Single Crystals

1998 ◽  
Vol 552 ◽  
Author(s):  
R. Srinivasan ◽  
M. F. Savage ◽  
R. D. Noebe ◽  
M. J. Mills
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Deformation Behavior ◽  
Mechanical Response ◽  
Slip Systems ◽  
Alloying Additions ◽  
Strain And Strain Rate ◽  
Deviation From Stoichiometry ◽  
Slip Transition ◽  
Active Slip

ABSTRACTNi-44A1, Ni-50Al and NiAl-0.3 at.% Hf single crystals have been studied in compression to understand the effects that alloying additions and deviation from stoichiometry can have on the mechanical response of NiAl-based single crystals. While all three single crystals deform through a<111> slip at lower temperatures, the active slip systems differ at higher temperatures. Climb of a<010> dislocations contributes to deformation in Ni-50AI single crystals beyond the slip transition temperature, while Ni-44Al and NiAl-0.3Hf crystals deform through a<101> glide. But several microstructural differences have been observed in the mode of deformation between Ni-44Al and NiAl-0.3Hf crystals. In addition, significant strengthening is exhibited in the Hf-doped crystals at higher temperatures. The post-deformation microstructure is also observed to be sensitive to both strain and strain rate. A possible explanation is offered for some of the observed differences in deformation behavior between the three alloys.

Single Crystal in Motion: An Insight into the Mechanism of Actuation

2014 ◽  
Vol 70 (a1) ◽  
pp. C1712-C1712
Author(s):  
Manas Panda ◽  
Pance Naumov
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Smart Materials ◽  
Mechanical Response ◽  
Shape Change ◽  
Systematic Investigation ◽  
External Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mechanical Actuation

Dynamic materials that can rapidly transform one form of energy into another have recently attracted attention because they could be utilized as platform for actuation from the nanoscale to the macroscale. This rapidly expanding field has brought up an increasing number of examples of oftentimes serendipitous observations of macro-, milli- and nano-sized single crystals that can hop, bend, curl or twist when exposed to light, heat or external pressure and have the capability to induce motion of other objects. Among these biomimetic crystalline actuators, the so-called thermosalient (TS) crystals, when heated or cooled, exhibit spectacular macroscopic motility as a result of fast coupling of thermal energy with mechanical actuation (Figure 1). Some of these crystals are exceptionally robust and undergo mechanical actuation for several cycles without disintegration. Achieving concurrently fast and reversible actuation of molecular crystals remains a great challenge since mechanical reconfiguration of single crystals is generally accompanied by loss of integrity (cracking, fracturing, explosion, etc.), a serious pitfall that limits their compatibility with the basic requirements for applications as dynamic modules. Despite the potential importance of these biomimetic crystalline actuators as smart materials, the detailed mechanism of actuation and shape change is not understood well. Here we report systematic investigation of the mechanism of mechanical response of these crystalline materials with the aid of single crystal X-ray diffraction, powder X-ray diffraction using synchrotron radiation, and other advanced instrumental techniques.

TEM In-Situ Study of Dislocation Motion in B2 NiAl Single Crystals

1996 ◽  
Vol 460 ◽  
Author(s):  
B. Ghosh ◽  
M. A. Crimp
Keyword(s):  
Single Crystals ◽  
High Purity ◽  
Mechanical Response ◽  
Tensile Deformation ◽  
Dislocation Motion ◽  
Thermal Treatments ◽  
Commercially Pure ◽  
Transmission Electron ◽  
Uniform Manner

ABSTRACTIn an effort to understand dislocation mobility in stoichiometric NiAl single crystals, in-situ tensile deformation experiments have been performed in a transmission electron microscope. Commercially pure and high purity single crystals with <001> and <110> orientations have been examined. Two different thermal treatments were adopted in order to effect the mechanical response. Dislocation motion was observed in all samples. Pre-existing dislocations, either isolated or tangled, were not observed to move at any point leading up to sample failure. Cross-slip of the mobile dislocations was observed in some cases. In commercially pure single crystals, dislocations were found to move at a much slower rate and uniform manner in contrast to motion in high purity single crystals which occurs by rapid jumps.

scholarly journals The Mechanical Response of Pre-Shocked Aluminium Single Crystals

2018 ◽  
Vol 183 ◽  
pp. 02010 ◽  
Author(s):  
Jeremy Millett ◽  
George. Gray ◽  
Glenn Whiteman ◽  
Saryu. Fensin ◽  
Gareth Owen
Keyword(s):  
Single Crystals ◽  
Shock Loading ◽  
Mechanical Response ◽  
Spall Strength ◽  
Significant Degree ◽  
Compression Tests ◽  
Static Compression ◽  
One Dimensional ◽  
Post Shock ◽  
Initial Dislocation Density

The behaviour of metals under mechanical loading, including shock loading conditions is strongly influenced by effects such as impurity levels, grain size, initial dislocation density and texture. The work discussed here is part of a wider study on the effects of orientation of aluminium single crystals to one dimensional shock loading, including the Hugoniot Elastic Limit and spall strength. In this work, specimens with three principle directions (<100>, <110> and <111>) parallel to the loading axis have been shock loaded and recovered under conditions of purely one-dimensional strain, with their post shock response monitored by quasi-static compression tests. Results show that the <100> crystal demonstrates a significant degree of post shock hardening, whilst the <111> crystal shows virtually none, and the <110> intermediate between the two. These results are consistent with the ordering of both the HELs and spall strengths observed in a previous paper, and have been explained in terms of the Schmidt factors.

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