Effects of Uniaxial Strain on the Structures of Vacancy Clusters in FCC Metals

2017 ◽  
Vol 898 ◽  
pp. 1340-1350 ◽  
Author(s):  
Fei Ye ◽  
Hong Bo Xv ◽  
Jin Mei Liu ◽  
Ke Tong
Keyword(s):  
Compressive Strain ◽  
Structural Evolution ◽  
The Body ◽  
Uniaxial Strain ◽  
Dominant Type ◽  
Vacancy Clusters ◽  
Fcc Metals ◽  
Stacking Fault Tetrahedron ◽  
Strain Axis ◽  
Simulation Condition

The effects of [001] uniaxial strain on the stable structures and structural evolution of vacancy clusters in fcc metals, Cu, Ni, Al and Fe, have been studied and compared. Under uniaxial strain, the clusters in all these metals tend to align parallel or perpendicular to the strain axis under tensile or compressive strain. Moreover, both the body cluster and the {001} planar cluster become the dominant types. In addition, the stacking fault tetrahedron cluster becomes another dominant type in Al under compressive strain. The cluster structures in Fe are disordered under strain possibly because the pure fcc Fe is thermodynamically unstable under the current simulation condition.

Effects of uniaxial strain on stability and structural evolution of vacancy clusters in copper

2016 ◽  
Vol 117 ◽  
pp. 361-369 ◽  
Author(s):  
Fei Ye ◽  
Jin Mei Liu ◽  
Ke Tong ◽  
Zitian Li ◽  
Honglong Che ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Uniaxial Strain ◽  
Vacancy Clusters

Structural evolution of vacancy clusters by combination of cluster units in alpha-iron

2014 ◽  
Vol 18 (sup4) ◽  
pp. S4-1003-S4-1006
Author(s):  
F. Ye ◽  
C. Yin ◽  
K. Tong ◽  
C. Zhang ◽  
W. B. Liu
Keyword(s):  
Structural Evolution ◽  
Alpha Iron ◽  
Vacancy Clusters

Highly Sensitive 2D Strain Sensor Using Carbon Nanotube

2013 ◽  
Author(s):  
Hiroshi Kawakami ◽  
Masato Ohnishi ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strain ◽  
Electronic Conductivity ◽  
Strain Sensor ◽  
Applied Strain ◽  
Uniaxial Strain ◽  
Sensitive Strain ◽  
Highly Sensitive ◽  
2D Strain ◽  
Walled Carbon Nanotubes

A new highly sensitive strain measurement method has been developed by applying the strain-induced change of the electronic conductivity of CNTs. It is reported that most multi-walled carbon nanotubes (MWCNTs) show metallic conductivity and they are rather cheap comparing with single-walled carbon nanotubes (SWCNTs). However, it was found that the electric conductivity of MWCNTs changes drastically under uniaxial strain because of the drastic change of their band gap. Therefore, the authors have developed a highly sensitive strain sensor which can detect the local strain distribution by using MWCNTs. In order to design a new sensor using MWCNT, it is very important to control the shape of the MWCNTs under strain. Thus, a method for controlling the shape of the MWCNTs was developed by applying a chemical vapor deposition (CVD) technique. It was found that the shape of the grown MWCNT could be controlled by changing the average thickness of the catalyst and the deposition temperature of the MWCNT. The electrical resistance of the grown MWCNT changed almost linearly with the applied strain, and the maximum strain sensitivity obtained under the application of uniaxial strain was about 10%/1000-μstrain (gauge factor: 100). A two-dimensional strain sensor, which consists of area-arrayed fine bundles of MWCNTs, has been developed by applying MEMS technology. Under the application of compressive strain, the electric resistance was confirmed to increase almost linearly with the applied strain.

scholarly journals Boudinage in Glacier Ice — Some Examples

1975 ◽  
Vol 14 (72) ◽  
pp. 383-393 ◽  
Author(s):  
M. J. Hambrey ◽  
A. G. Milnes
Keyword(s):  
Compressive Strain ◽  
Coarse Grained ◽  
Planar Anisotropy ◽  
Fine Grained ◽  
Or Groups ◽  
First Results ◽  
Glacier Ice ◽  
Strain Axis ◽  
The Difference ◽  
Shear Planes

Boudinage structures have only rarely been reported in glacier ice, yet they seem to be widespread in Swiss glaciers. They form in debris-free, strongly foliated ice by the stretching, necking and rupture of layers or groups of layers, when the principal compressive strain axis lies at a high angle to the layering. Two main types of boudinage are distinguished. The first results from the difference in competence between fine-grained and coarse-grained ice, and indicates that the former is more resistant to flow than the latter. The second occurs in more equigranular ice which shows a strong planar anisotropy; associated with the necking of such ice is the development of shear planes, along which the layers are displaced. As in deformed rocks, it is not possible to determine the directions of the finite principal strain axes from the boudinage structures alone. Although the boudins described here all occur in longitudinal foliation, it is suggested that they are likely to form in other situations also.

scholarly journals Strain Dependence of Energetics and Kinetics of Vacancy in Tungsten

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3375
Author(s):  
Zhong-Zhu Li ◽  
Yu-Hao Li ◽  
Qing-Yuan Ren ◽  
Fang-Fei Ma ◽  
Fang-Ya Yue ◽  
...  
Keyword(s):  
Binding Energy ◽  
First Principles ◽  
Tensile Strain ◽  
Kinetic Monte Carlo ◽  
Compressive Strain ◽  
Biaxial Strain ◽  
Poisson Effect ◽  
Vacancy Clusters ◽  
Object Kinetic Monte Carlo ◽  
Kinetic Monte Carlo Simulations

We investigate the influence of hydrostatic/biaxial strain on the formation, migration, and clustering of vacancy in tungsten (W) using a first-principles method, and show that the vacancy behaviors are strongly dependent on the strain. Both a monovacancy formation energy and a divacancy binding energy decrease with the increasing of compressive hydrostatic/biaxial strain, but increase with the increasing of tensile strain. Specifically, the binding energy of divacancy changes from negative to positive when the hydrostatic (biaxial) tensile strain is larger than 1.5% (2%). These results indicate that the compressive strain will facilitate the formation of monovacancy in W, while the tensile strain will enhance the attraction between vacancies. This can be attributed to the redistribution of electronic states of W atoms surrounding vacancy. Furthermore, although the migration energy of the monovacancy also exhibits a monotonic linear dependence on the hydrostatic strain, it shows a parabola with an opening down under the biaxial strain. Namely, the vacancy mobility will always be promoted by biaxial strain in W, almost independent of the sign of strain. Such unexpected anisotropic strain-enhanced vacancy mobility originates from the Poisson effect. On the basis of the first-principles results, the nucleation of vacancy clusters in strained W is further determined with the object kinetic Monte Carlo simulations. It is found that the formation time of tri-vacancy decrease significantly with the increasing of tensile strain, while the vacancy clusters are not observed in compressively strained W, indicating that the tensile strain can enhance the formation of voids. Our results provide a good reference for understanding the vacancy behaviors in W.

scholarly journals WxNbMoTa Refractory High-Entropy Alloys Fabricated by Laser Cladding Deposition

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 533 ◽  
Author(s):  
Qingyu Li ◽  
Hang Zhang ◽  
Dichen Li ◽  
Zihao Chen ◽  
Sheng Huang ◽  
...  
Keyword(s):  
Laser Cladding ◽  
Compressive Strain ◽  
The Body ◽  
Vacuum Arc ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Refractory Alloys ◽  
Arc Melting ◽  
Bcc Structure ◽  
Tungsten Concentration

WxNbMoTa refractory high-entropy alloys with four different tungsten concentrations (x = 0, 0.16, 0.33, 0.53) were fabricated by laser cladding deposition. The crystal structures of WxNbMoTa alloys are all a single-phase solid solution of the body-centered cubic (BCC) structure. The size of the grains and dendrites are 20 μm and 4 μm on average, due to the rapid solidification characteristics of the laser cladding deposition. These are much smaller sizes than refractory high-entropy alloys fabricated by vacuum arc melting. In terms of integrated mechanical properties, the increase of the tungsten concentration of WxNbMoTa has led to four results of the Vickers microhardness, i.e., Hv = 459.2 ± 9.7, 476.0 ± 12.9, 485.3 ± 8.7, and 497.6 ± 5.6. As a result, NbMoTa alloy shows a yield strength (σb) and compressive strain (εp) of 530 Mpa and 8.5% at 1000 °C, leading to better results than traditional refractory alloys such as T-111, C103, and Nb-1Zr, which are commonly used in the aerospace industry.

scholarly journals An analysis of compressive strain in adjacent temperature-gradient and equi-temperature layers in a natural snow cover

1980 ◽  
Vol 26 (94) ◽  
pp. 283-289 ◽  
Author(s):  
Richard L. Armstrong
Keyword(s):  
Strain Rate ◽  
Snow Cover ◽  
Compressive Strain ◽  
Coarse Grained ◽  
Adjacent Layer ◽  
Dominant Type ◽  
Fine Grained ◽  
Order Of Magnitude ◽  
Alpine Research ◽  
Natural Snow

AbstractCompressive strain-rates in discrete layers of a sub-alpine snow cover are analyzed. Individual layers are identified according to density and the dominant type of metamorphism which contributed to their formation. Data were collected during four winter seasons at the Institute of Arctic and Alpine Research (INSTAAR) snow-study site (3 400 m), Red Mountain Pass, south-western Colorado, U.S.A. At average densities of less than 250 kg m₋3the influence of metamorphism on strain-rate is not apparent. However, at densities greater than 250 kg m₋3, two separate relationships emerge for strain as a function of crystal type and density. While two adjacent layers may exhibit comparable densities, a layer of sintered, fine grained (ET) snow indicates a strain-rate approximately one order of magnitude greater than an adjacent layer of cohesionless, coarse-grained (TG) snow.

Global and Local Structural Evolution during Deformation and Annealing of FCC Metals

2007 ◽  
Vol 550 ◽  
pp. 169-180 ◽  
Author(s):  
Niels Hansen
Keyword(s):  
Lamellar Structure ◽  
Structural Changes ◽  
Large Strain ◽  
Structural Evolution ◽  
Structural Difference ◽  
Rolling Texture ◽  
High Angle ◽  
Fcc Metals ◽  
Microstructural Parameters ◽  
Global And Local

Deformation of metals from medium to high strain significantly affect the deformation structure as well as the recovery and recrystallization behaviour when deformed samples are annealed. This behaviour is illustrated for FCC metals of medium to high stacking fault energy, with emphasis on the behaviour of aluminium and aluminium alloys deformed by cold rolling to large strain. The analysis encompasses hardness testing, EBSD and TEM. The deformation microstructure is a lamellar structure of dislocation boundaries and high angle boundaries where the percentages of the latter increases to about 60-80% at large strain. The macrotexture is a typical rolling texture, which is composed of individual texture components present as micrometre and submicrometre size volumes. In the lamellar structure correlations have been established between microstructural parameters and local orientations showing for example variations in stored energy between the texture components and large variations in the spatial distributions of the high angle lamellar boundaries. Such local variations can affect the structural coarsening during recovery at low temperature leading to significant structural difference on a local scale. The local variations in the deformed structure can also significantly affect the structural changes taking place locally during high temperature annealing thereby affecting the evolution of the structure and texture on a macroscopic scale.

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