Phenomenology of chiral Dzyaloshinskii-Moriya interactions in strained materials

The purpose of this study is to clarify the creep deformation behavior and microstructural degradation during creep of pre-strained 25Cr-20Ni-Nb-N steel (TP310HCbN), which has the highest creep strength among austenite stainless steels used for boiler tubes. The creep rupture strengths of the 20% pre-strained materials tested at 650°C under 210 MPa and 180 MPa were higher than those of solution-treated materials. However, the long time creep rupture strengths of the 20% pre-strained materials tested at 700°C and 750°C were lower than those of solution-treated materials. Thus, the creep strengths of the prestrained materials depend on test temperature and stress. Furthermore, the minimum creep rate of the 20% pre-strained materials and re-solution-treated materials tested at 650°C under 300MPa were 1.2 × 10−9 and 1.6 × 10−8 s−1, respectively. Thus, the minimum creep rate of the 20% pre-strained materials was lower than for re-solution-treated materials. The creep strengthening mechanism of the pre-strained materials at 650°C was considered to be that high-density dislocations were maintained until the late stage of creep. On the other hand, the creep rupture strengths of the 20% pre-strained materials were lower than those of solution-treated materials tested at over 700°C because of agglomeration and coarsening of precipitates and the recovery of dislocations.

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Effect of changes in the elastic characteristics of plastically strained materials on residual stresses

Strength of Materials ◽

10.1007/bf00763009 ◽

1973 ◽

Vol 5 (6) ◽

pp. 728-730

Author(s):

V. V. Abramov ◽

A. V. Tonkonog ◽

A. M. Rudich ◽

Zh. G. Ovanesova

Keyword(s):

Residual Stresses ◽

Strained Materials ◽

Elastic Characteristics

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Effect of Alloy Disorder Scattering on Electron Mobility Model for Strained-Si1-xGex/Si (101)

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.181-182.364 ◽

2011 ◽

Vol 181-182 ◽

pp. 364-369

Author(s):

Cheng Wang ◽

He Ming Zhang ◽

Rong Xi Xuan ◽

Hui Yong Hu

Keyword(s):

Applied Stress ◽

Electron Mobility ◽

Physical Phenomenon ◽

Mobility Model ◽

Strained Si ◽

Electron Effective Mass ◽

Scattering Rate ◽

Alloy Disorder ◽

Strained Materials ◽

Disorder Scattering

Si-based strained technology is currently an important topic of concern in the microelectronics field. The stress-induced enhancement of electron mobility contributes to the improved performance of Si-based strained devices. In this paper, Based on both the electron effective mass and the scattering rate models for strained-Si1-xGex/Si (101), an analytical electron mobility model for biaxial compressive strained-Si1-xGex /Si (101) is presented. The results show that the stress doesn’t make the electron mobility increased, but the electron mobility for [100] and [001] orientations decrease with increasing Ge fraction x, especially for [010] orientation expresses a sharp decrease. This physical phenomenon can be explained as: Although the applied stress (the higher the Ge fraction, the greater the applied stress) can enhance the electron mobility, alloy disorder scattering rate markedly increase. Overall the electron mobility decreases instead. The above result suggests that not all the mobilities for Si-based strained materials enhance with the stress applied. For the biaxial strained-SiGe material represented by Ge fraction, the effect of alloy disorder scattering on the enhancement of mobility must be concerned. The result can provide theoretical basis for the understanding of the improved physical characterizations and the enhanced mobility for Si-based strained materials.

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Fatigue-free, superstretchable, transparent, and biocompatible metal electrodes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1516873112 ◽

2015 ◽

Vol 112 (40) ◽

pp. 12332-12337 ◽

Cited By ~ 56

Author(s):

Chuan Fei Guo ◽

Qihan Liu ◽

Guohui Wang ◽

Yecheng Wang ◽

Zhengzheng Shi ◽

...

Keyword(s):

Flexible Electronics ◽

Indium Tin Oxide ◽

Large Strain ◽

Transparent Conductors ◽

Practical Applications ◽

Highly Stretchable ◽

Implantable Electronics ◽

Electronic Conductors ◽

Strained Materials ◽

Original Configuration

Next-generation flexible electronics require highly stretchable and transparent electrodes. Few electronic conductors are both transparent and stretchable, and even fewer can be cyclically stretched to a large strain without causing fatigue. Fatigue, which is often an issue of strained materials causing failure at low strain levels of cyclic loading, is detrimental to materials under repeated loads in practical applications. Here we show that optimizing topology and/or tuning adhesion of metal nanomeshes can significantly improve stretchability and eliminate strain fatigue. The ligaments in an Au nanomesh on a slippery substrate can locally shift to relax stress upon stretching and return to the original configuration when stress is removed. The Au nanomesh keeps a low sheet resistance and high transparency, comparable to those of strain-free indium tin oxide films, when the nanomesh is stretched to a strain of 300%, or shows no fatigue after 50,000 stretches to a strain up to 150%. Moreover, the Au nanomesh is biocompatible and penetrable to biomacromolecules in fluid. The superstretchable transparent conductors are highly desirable for stretchable photoelectronics, electronic skins, and implantable electronics.

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E-kRelation of Valence Band in Arbitrary Orientation/Typical Plane Uniaxially Strained

Advances in Condensed Matter Physics ◽

10.1155/2014/686303 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9

Author(s):

Zhang Chao ◽

Xu Da-Qing ◽

Liu Shu-Lin ◽

Liu Ning-Zhuang

Keyword(s):

Valence Band ◽

Theoretical Basis ◽

Carrier Mobility ◽

Energy Levels ◽

Hole Mobility ◽

Strained Si ◽

Effective Masses ◽

Splitting Energy ◽

Analytic Models ◽

Strained Materials

Uniaxial strain technology is an effective way to improve the performance of the small size CMOS devices, by which carrier mobility can be enhanced. TheE-krelation of the valence band in uniaxially strained Si is the theoretical basis for understanding and enhancing hole mobility. The solving procedure of the relation and its analytic expression were still lacking, and the compressive results of the valence band parameters in uniaxially strained Si were not found in the references. So, theE-krelation has been derived by taking strained Hamiltonian perturbation into account. And then the valence band parameters were obtained, including the energy levels at Γ point, the splitting energy, and hole effective masses. Our analytic models and quantized results will provide significant theoretical references for the understanding of the strained materials physics and its design.

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Investigation of Effect of Pre-Strain on Very High-Cycle Fatigue Strength of Austenitic Stainless Steels

Volume 1: Plant Operations, Maintenance, Installations and Life Cycle; Component Reliability and Materials Issues; Advanced Applications of Nuclear Technology; Codes, Standards, Licensing and Regulatory Issues ◽

10.1115/icone16-48811 ◽

2008 ◽

Author(s):

Takeshi Ogawa ◽

Motoki Nakane ◽

Kiyotaka Masaki ◽

Shota Hashimoto ◽

Yasuo Ochi ◽

...

Keyword(s):

Fatigue Strength ◽

Nuclear Power ◽

Power Plants ◽

Austenitic Stainless Steels ◽

Fatigue Tests ◽

Structural Components ◽

Very High Cycle Fatigue ◽

Tension And Compression ◽

Strained Materials ◽

Very High

The austenitic stainless steels have excellent mechanical and chemical characteristics and these materials are widely used for the main structural components in the nuclear power plants. A part of structural components using these materials is considered to have strain-history by machining, welding and etc in the process of manufacturing and these parts would be hardened because these materials have a remarkable work-hardening property. On the other hand, conventional studies for the fatigue strength used to be investigated by the results of fatigue tests applying normal specimens without the effect of hardening by pre-strain. This paper describes the effect of large pre-strain on very high cycle fatigue strength of the materials in consideration for the evaluation of strength of actual structures in the nuclear power plants. In order to achieve this purpose, the fatigue tests were carried out with strain hardened specimens. The material served in this study was type SUS316NG. Up to ±20% pre-strain was introduced to the round bar shaped materials by tension and compression load test, and the materials were mechanically machined to the hourglass shaped smooth specimens. On the other hand, the pre-strain of some specimens were introduced after machining so as to study the influence of roughness of the surface of the specimens for the fatigue property. Fatigue tests were conducted by ultrasonic and rotating-bending fatigue test machines and conditions were decided by preliminary examinations to control temperature elevation of the specimen during the fatigue test. The S-N curves obtained from fatigue tests show that increase in magnitude of the pre-strain cause increase in the fatigue strength of the material and this relationship is independent of type of the pre-strains of tension and compression. Though all specimens were fractured by the surface initiated fatigue crack, only one specimen was fractured by the internal crack and so-called “fish-eye” was observed on the fracture surface. However, the internal fracture of the SUS316NG does not cause sudden drop of the fatigue strength. Also, the Vickers hardness tests were carried out to discuss the relationship between fatigue strength and hardness of the pre-strained materials. It is found that the increase in fatigue limit of the pre-strained materials strongly depend on the hardness derived from the indentation size equals to the scale of stage I fatigue crack.

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Determining the principal axes of anisotropy in strained materials by the ultrasonic method

Soviet Applied Mechanics ◽

10.1007/bf00885915 ◽

1972 ◽

Vol 8 (1) ◽

pp. 59-63

Author(s):

A. A. Lukashev ◽

V. G. �ichina ◽

G. G. Agas'ev

Keyword(s):

Ultrasonic Method ◽

Principal Axes ◽

Strained Materials

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