Comment on “Ultralow magnetostrictive flexible ferromagnetic nanowires” by G. Muscas, P. E. Jönsson, I. G. Serrano, Ö. Vallin, and M. V. Kamalakar, Nanoscale, 2021, 13, 6043–6052

Nanoscale ◽  
2022 ◽  
Author(s):  
D. Faurie ◽  
N. Challab ◽  
M. Haboussi ◽  
F. Zighem
Keyword(s):  
Applied Stress ◽  
Strain Field ◽  
Uniaxial Stress ◽  
Macroscopic Strain ◽  
Ferromagnetic Nanowires

A strain field (εxx) in Ti/Co/Al nanowires on the PEN substrate subjected to uniaxial stress. The applied stress perpendicular to the nanowire length leads to very low strain in nanowires (about 30 times lower than the macroscopic strain).

Straining Effects in Silica-Filled Elastomers Investigated by Atomic Force Microscopy: From Macroscopic Stretching to Nanoscale Strainfield

2003 ◽  
Vol 76 (1) ◽  
pp. 60-81 ◽  
Author(s):  
A. Lapra ◽  
F. Clément ◽  
L. Bokobza ◽  
L. Monnerie
Keyword(s):  
Atomic Force Microscopy ◽  
Strain Field ◽  
Local Concentration ◽  
Macroscopic Strain ◽  
Precise Description ◽  
Force Microscopy ◽  
Filled Elastomers ◽  
Atomic Force ◽  
Different Strains ◽  
Very High

Abstract Understanding the way fillers can reinforce elastomers requires, among other things, requires a precise description of the behavior of filler aggregates when a macroscopic strain is applied. In this study, Atomic Force Microscopy was used to investigate samples of SBR and PDMS filled with silica. The samples were stretched uniaxially at different strain values (up to 145%) and imaged by Atomic Force Microscopy. The distances between aggregates were followed at the different strains, which allowed calculation of the local strains and comparison of the values obtained with the macroscopic strain value. The main results are (i) that the strain field is highly heterogeneous, depending on the local concentration of filler and (ii) that the strain undergone by elastomer chains can be very high locally, in the regions where distances between aggregates are very short.

Shape of α'R. Zn Rich Precipitatesin Al Zn Alloys. Effect of an Uniaxial Stress on Decomposition

1982 ◽  
Vol 21 ◽  
Author(s):  
F. Livet
Keyword(s):  
Cross Section ◽  
Small Angle ◽  
Strain Field ◽  
Small Angle Neutron Scattering ◽  
Uniaxial Stress ◽  
Mean Value ◽  
Initial Composition ◽  
The Matrix ◽  
C Value ◽  
Zn Alloys

ABSTRACTDuring the first stages of decomposition of Al Zn alloys, spherical GP zones are observed. On further ageing of the samples, the precipitates have the shape of flat ellipsoids, the small axis of which are in the various <111> directions.We have followed such an evolution in single crystals by small angle neutron scattering. From the asymptotic behavior of the cross section, we have calculated the size (c) of the small semiaxis of the ellipsoids. We show that c is almost independent of the initial composition of our samples (5.3, 6.8, 12.1 at Zn %), independent of the other dimensions of the “α'R” precipitates and very sharply distributed around its mean value (c = 24.5 ± 2 Å at 293°C).The strain field in the matrix must clearly be involved in the limitation of the c value. We have studied the effect of a uniaxial [110] compressive stress applied during ageing. Neutron small angle experiments, carried on an Al-12.1 at % Zn single crystal show that the c value remains the same. The scattering in the [111] and [11] directions is much higher than in the [111] and [111] directions. This is mainly due to the fact that the stress favors the number of [111] and [111] type of α'R precipitates.

Uniaxial stress and magnetic field dependence of the In- and Tl-related isoelectronic bound excitons in Si

1985 ◽  
Vol 63 (8) ◽  
pp. 1074-1082 ◽  
Author(s):  
S. P. Watkins ◽  
M. L. W. Thewalt
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Strain Field ◽  
Magnetic Field Dependence ◽  
Zeeman Splitting ◽  
Uniaxial Stress ◽  
Internal Strain ◽  
Final States ◽  
Photoluminescence Spectra ◽  
Angular Momenta

We present the results of uniaxial stress and Zeeman splitting measurements on the photoluminescence spectra of the unique isoelectronic bound excitons found in In- and Tl-doped Si, which are known to exist in two very different configurations. Our results indicate that these two configurations correspond to the two known classes of isoelectronic bound excitons, which differ in the sign of their internal strain field. We also show that the results are not in agreement with previous suggestions that these isoelectronic bound exciton transitions have half-integer angular momenta in both the initial and final states.

Effect of macroscopic deformation on lung microstructure

1996 ◽  
Vol 81 (4) ◽  
pp. 1792-1799 ◽  
Author(s):  
James P. Butler ◽  
Hiroshi Miki ◽  
Stephanie Squarcia ◽  
Rick A. Rogers ◽  
John L. Lehr
Keyword(s):  
Light Scattering ◽  
Strain Field ◽  
Geometric Mean ◽  
Specific Model ◽  
Diffuse Light ◽  
Optical Technique ◽  
Macroscopic Strain ◽  
Model Predictions ◽  
Macroscopic Deformation ◽  
Low Shear

Butler, James P., Hiroshi Miki, Stephanie Squarcia, Rick A. Rogers, and John L. Lehr. Effect of macroscopic deformation on lung microstructure. J. Appl. Physiol.81(4): 1792–1799, 1996.—Using an anisotropic theory of diffuse light scattering in lungs, we measured the fractional changes in geometric mean linear intercepts in orthogonal directions when freshly excised rabbit lungs were subjected to isovolume uniaxial strains. Results from the optical technique were compared with morphometric estimates of fractional changes in mean linear intercepts from the same strained and unstrained (control) lobes, with the conclusion that diffuse light scattering is adequate to estimate changes in mean free paths in different directions. We compared optical estimates of fractional changes in mean linear intercepts with the macroscopic strain field measured by displacements of pleural markers; this relationship did not significantly differ from the line of identity. We conclude that the microscopic strain field is closely matched to the macroscopic strain field during uniaxial distortion. This suggests that surface reorientation may not play a large role in the origin of the low shear modulus of the lung, but this cannot be definitively stated without comparison of these experimental results to specific model predictions of the changes in mean linear intercepts in shear deformation.

Plastic Deformation in Microtomed Sections

1971 ◽  
Vol 29 ◽  
pp. 458-459
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Applied Stress ◽  
Elastic Strain ◽  
High Strain ◽  
Tool Material ◽  
Cutting Edge ◽  
Material Structure ◽  
Geometrical Constraints

The output of the ultramicrotomy process with its high strain levels is dependent upon the input, ie., the nature of the material being machined. Apart from the geometrical constraints offered by the rake and clearance faces of the tool, each material is free to deform in whatever manner necessary to satisfy its material structure and interatomic constraints. Noncrystalline materials appear to survive the process undamaged when observed in the TEM. As has been demonstrated however microtomed plastics do in fact suffer damage to the top and bottom surfaces of the section regardless of the sharpness of the cutting edge or the tool material. The energy required to seperate the section from the block is not easily propogated through the section because the material is amorphous in nature and has no preferred crystalline planes upon which defects can move large distances to relieve the applied stress. Thus, the cutting stresses are supported elastically in the internal or bulk and plastically in the surfaces. The elastic strain can be recovered while the plastic strain is not reversible and will remain in the section after cutting is complete.

Evidence for a shear mechanism for the precipitation of γ-zirconium hydride in zirconium

1978 ◽  
Vol 36 (1) ◽  
pp. 658-659
Author(s):  
G.J.C. Carpenter
Keyword(s):  
Elevated Temperature ◽  
Strain Field ◽  
Zirconium Hydride ◽  
Zirconium Atom ◽  
Atom Diffusion ◽  
Solvus Temperature ◽  
Hexagonal Close Packed ◽  
Partial Dislocations ◽  
The Face

In zirconium-hydrogen alloys, rapid cooling from an elevated temperature causes precipitation of the face-centred tetragonal (fct) phase, γZrH, in the form of needles, parallel to the close-packed <1120>zr directions (1). With low hydrogen concentrations, the hydride solvus is sufficiently low that zirconium atom diffusion cannot occur. For example, with 6 μg/g hydrogen, the solvus temperature is approximately 370 K (2), at which only the hydrogen diffuses readily. Shears are therefore necessary to produce the crystallographic transformation from hexagonal close-packed (hep) zirconium to fct hydride.The simplest mechanism for the transformation is the passage of Shockley partial dislocations having Burgers vectors (b) of the type 1/3<0110> on every second (0001)Zr plane. If the partial dislocations are in the form of loops with the same b, the crosssection of a hydride precipitate will be as shown in fig.1. A consequence of this type of transformation is that a cumulative shear, S, is produced that leads to a strain field in the surrounding zirconium matrix, as illustrated in fig.2a.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

Strain analysis in composite ceramics

1986 ◽  
Vol 44 ◽  
pp. 494-497
Author(s):  
W. M. Kriven
Keyword(s):  
Strain Field ◽  
Strain Analysis ◽  
Processing Temperature ◽  
Transformation Toughening ◽  
Zirconia Ceramics ◽  
Volume Increase ◽  
Analysis Technique ◽  
Fundamental Understanding ◽  
Contrast Analysis ◽  
Elastic Strain Field

Significant progress towards a fundamental understanding of transformation toughening in composite zirconia ceramics was made possible by the application of a TEM contrast analysis technique for imaging elastic strains. Spherical zirconia particles dispersed in a large-grained alumina matrix were examined by 1 MeV HVEM to simulate bulk conditions. A thermal contraction mismatch arose on cooling from the processing temperature of 1500°C to RT. Tetragonal ZrO2 contracted amisotropically with α(ct) = 16 X 10-6/°C and α(at) = 11 X 10-6/°C and faster than Al2O3 which contracted relatively isotropically at α = 8 X 10-6/°C. A volume increase of +4.9% accompanied the transformation to monoclinic symmetry at room temperature. The elastic strain field surrounding a particle before transformation was 3-dimensionally correlated with the internal crystallographic orientation of the particle and with the strain field after transformation. The aim of this paper is to theoretically and experimentally describe this technique using the ZrO2 as an example and thereby to illustrate the experimental requirements Tor such an analysis in other systems.

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