scholarly journals Helium Effects on the Mechanical Properties of Nanocrystalline Fe: Based on Molecular Dynamics

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 532
Author(s):  
Chunping Xu ◽  
Dongyan Yang
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Lattice Distortion ◽  
Tensile Deformation ◽  
Peak Stress ◽  
X Ray Diffraction ◽  
Peak Separation ◽  
Tensile Process ◽  
Xrd Patterns ◽  
The Relationship

A molecular dynamics (MD) simulation study was performed to investigate the effects of helium (He) on the mechanical properties of nanocrystalline body-centered cubic iron (BCC Fe). Simulated X-ray diffraction (XRD) was used to explore the relationship between the generation of cracks and the change of the crystal structure in nanocrystalline BCC Fe during tensile deformation. It is observed that the peak stress and the elastic modulus decrease with increasing concentration of He atoms, which are introduced into the grain boundary (GB) region of nanocrystalline Fe. The generation and connection of intergranular cracks are enhanced by He atoms. Significant peak separation, which is associated with the generation of cracks, is found in the simulated XRD patterns of nanocrystalline Fe during the tensile process. The lower diffraction angle of the {211}′ peak suggests a more serious lattice distortion during loading. For all nanocrystalline Fe deformed to 6% strain, the degree and fraction of the lattice distortion increases with the increasing loading stress.

Molecular Dynamics Simulation of Crack Initiation of Aluminum under Tensile Deformation

2011 ◽  
Vol 378-379 ◽  
pp. 7-10
Author(s):  
Gui Xue Bian ◽  
Yue Liang Chen ◽  
Jian Jun Hu ◽  
Li Xu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Elastic Constants ◽  
Tensile Deformation ◽  
Crack Nucleation ◽  
Tensile Load ◽  
Dynamics Simulation ◽  
Metal Aluminum ◽  
Impurity Metal

Molecular dynamics simulation was used to simulate the tension process of purity and containing impurity metal aluminum. Elastic constants of purity and containing impurity metal aluminum were calculated, and the effects of impurity on the elastic constants were also studied. The results show that O-Al bond and Al-Al bond near oxygen atoms could be the sites of crack nucleation or growth under tensile load, the method can be extended to research mechanical properties of other metals and alloys structures.

Effects of Different Sintering Temperature on the Microstructure and Piezoelectric Properties of Pb(Nb2/3Zn1/3)x(Zr52Ti48)1-XO3 Ceramics

2014 ◽  
Vol 1061-1062 ◽  
pp. 83-86
Author(s):  
Hong Wu ◽  
De Yi Zheng
Keyword(s):  
Electrical Properties ◽  
Electromechanical Coupling ◽  
Piezoelectric Properties ◽  
Sintering Temperature ◽  
Electromechanical Coupling Coefficient ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
Xrd Patterns ◽  
The Relationship

In this paper, the effects of different sintering temperature on the microstructure and piezoelectric properties of Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3(PNZZT) ceramic samples were investigated. The Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 ceramics materials was prepared by a conventional mixed oxide method. In the period of the experiment, the relationship between crystallographic phase and microstructure were analyzed by X-ray diffraction(XRD) and scanning electron microscopy(SEM) respectively. The XRD patterns shows that all of the ceramic samples are with a tetragonal perovskite structure. Along with sintering temperature increased and the x is 0.03, the grain size gradually become big. Through this experiment, it has been found that when the x is 0.03 and sintered at 1130°C for 2 h, the grains grow well, the grain-boundary intersection of the sample combined well and the porosity of the ceramics decreased, an excellent comprehensive electrical properties of the Pb(Nb2/3Zn1/3)0.03(Zr52Ti48)0.97O3 samples can be obtained. Its best electrical properties are as follows: dielectric constant (ε) is 1105, dielectric loss(tg) is 0.017, electromechanical coupling coefficient (Kp) is 0.287, piezoelectric constant(d33) is 150PC/N

scholarly journals Influence of Temperature on Mechanical Properties of P(BAMO-r-THF) Elastomer

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2507
Author(s):  
Jinxian Zhai ◽  
Hanpeng Zhao ◽  
Xiaoyan Guo ◽  
Xiaodong Li ◽  
Tinglu Song
Keyword(s):  
Mechanical Properties ◽  
X Ray Diffraction ◽  
Polymeric Chains ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
Strain Induced Crystallization ◽  
Thermal Histories ◽  
Static Conditions ◽  
The Relationship ◽  
Induced Crystallization

The relationship between temperature and the mechanical properties of an end cross-linked equal molar random copolyether elastomer of 3,3-bis(azidomethyl)oxetane and tetrahydrofuran (P(BAMO-r-THF)) was investigated. During this investigation, the performances of two P(BAMO-r-THF) elastomers with different thermal histories were compared at different temperatures. The elastomer as prepared at 20 °C (denoted as S0) exhibited semi-crystallization morphology. Wide angle X-ray diffraction analysis indicated that the crystal grains within elastomer S0 result from the crystallization of BAMO micro-blocks embedded in P(BAMO-r-THF) polymeric chains, and the crystallinity is temperature irreversible under static conditions. After undergoing a heating-cooling cycle, this elastomer became an amorphous elastomer (denoted as S1). Regarding mechanical properties, at 20 °C, break strains and stresses of 315 ± 22% and 0.46 ± 0.01 MPa were obtained for elastomer S0; corresponding values of 294 ± 6% and 0.32 ± 0.02 MPa were obtained for elastomer S1. At −40 °C, these strains and stresses simultaneously increased to 1085 ± 21% and 8.90 ± 0.72 MPa (S0) and 1181 ± 25% and 10.23 ± 0.44 MPa (S1), respectively, owing to the strain-induced crystallization of BAMO micro-blocks within the P(BAMO-r-THF) polymeric chains.

scholarly journals Isotropic microscale mechanical properties of coral skeletons

2015 ◽  
Vol 12 (106) ◽  
pp. 20150168 ◽  
Author(s):  
Luca Pasquini ◽  
Alan Molinari ◽  
Paola Fantazzini ◽  
Yannicke Dauphen ◽  
Jean-Pierre Cuif ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Nacreous Layer ◽  
X Ray Diffraction ◽  
Stylophora Pistillata ◽  
Force Microscopy ◽  
Coral Skeletons ◽  
Atomic Force ◽  
Diffraction Patterns ◽  
The Relationship ◽  
Atrina Rigida

Scleractinian corals are a major source of biogenic calcium carbonate, yet the relationship between their skeletal microstructure and mechanical properties has been scarcely studied. In this work, the skeletons of two coral species: solitary Balanophyllia europaea and colonial Stylophora pistillata , were investigated by nanoindentation. The hardness H IT and Young's modulus E IT were determined from the analysis of several load–depth data on two perpendicular sections of the skeletons: longitudinal (parallel to the main growth axis) and transverse. Within the experimental and statistical uncertainty, the average values of the mechanical parameters are independent on the section's orientation. The hydration state of the skeletons did not affect the mechanical properties. The measured values, E IT in the 76–77 GPa range, and H IT in the 4.9–5.1 GPa range, are close to the ones expected for polycrystalline pure aragonite. Notably, a small difference in H IT is observed between the species. Different from corals, single-crystal aragonite and the nacreous layer of the seashell Atrina rigida exhibit clearly orientation-dependent mechanical properties. The homogeneous and isotropic mechanical behaviour of the coral skeletons at the microscale is correlated with the microstructure, observed by electron microscopy and atomic force microscopy, and with the X-ray diffraction patterns of the longitudinal and transverse sections.

scholarly journals Synthesis of Na-Doped Lithium Metatitanate and Its Absorption for Carbon Dioxide

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Liu Zhirong ◽  
Zhang Huan ◽  
Wang Yun ◽  
Zhan Xinxing
Keyword(s):  
Carbon Dioxide ◽  
Solid State Reaction Method ◽  
Absorption Capacity ◽  
Absorption Kinetics ◽  
X Ray Diffraction ◽  
Carbon Dioxide Absorption ◽  
Reaction Method ◽  
X Ray ◽  
Xrd Patterns ◽  
The Relationship

Na-doped lithium metatitanate (Na-doped Li2TiO3) absorbent was doped with Na2CO3and lithium metatitanate (Li2TiO3) was prepared by a solid-state reaction method from mixture of TiO2and Li2CO3. The Na-doped lithium metatitanate was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and surface area. Carbon dioxide absorption on Na-doped lithium metatitanate was investigated using TG-DTA. The results reveal an increase of the CO2absorption capacity of the Na-doped materials with respect to pure Li2TiO3. XRD patterns of the doped samples suggest a limited substitution of Li by Na atoms within the Li2TiO3structure. The results of experimental and modeling work were summarized to better understand the relationship between the sorbent microstructure and carbon dioxide absorption kinetics.

Molecular Dynamics Simulation of Surface Effect on Tensile Deformation of Single Crystalline Copper

2014 ◽  
Vol 620 ◽  
pp. 61-66 ◽  
Author(s):  
Qiang Gao ◽  
Yong Bo Guo ◽  
Ying Chun Liang ◽  
Qing Chun Zhang
Keyword(s):  
Molecular Dynamics ◽  
Tensile Deformation ◽  
Surface Effect ◽  
High Energy ◽  
Dislocation Nucleation ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Crystal Plane ◽  
Single Crystalline ◽  
Tensile Process

Based on molecular dynamics method, the tensile process of single crystalline Cu nanorod and single crystalline Cu bulk were simulated at atomic scale. The motion of atoms, total energy of atom-strain curves and number of dislocation atom-strain curves during the tensile process were acquired. The results shown that surface effect has a significant effect on the tensile mechanical properties of single crystalline Cu nanorod. For single crystalline Cu nanorod, the energy of atoms in the edges and surface were higher than the energy of atoms inside the nanorod. Dislocations nucleation in the edges that with high energy and extend along the {111} crystal plane. The nanorods produce plastic deformation and shows excellent ductility under the "dislocation nucleation-energy rising and dislocation layers cross-slip" mechanism of the alternating cycle. For single crystalline Cu bulk, dislocation nucleation randomly and extend to the entire simulation model along the {111} crystal plane quickly. The single crystalline bulk Cu produce fracture under the "microscopic vacancy-microscopic hole-penetration of microscopic holes-fracture" mechanism.

Experimental and Theoretical Study of Air-Entraining Concrete under Biaxial Compression after Freezing-Thawing Cycle

2011 ◽  
Vol 243-249 ◽  
pp. 214-217
Author(s):  
Jia Wei Yao ◽  
Yu Pu Song ◽  
Ling Xia Gao
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Failure Criterion ◽  
Theoretical Study ◽  
Peak Stress ◽  
Biaxial Compression ◽  
Thawing Cycle ◽  
Experiment Method ◽  
Strength And Deformation ◽  
The Relationship

Mechanical properties experiments of air-entraining concrete after suffered to 0, 100, 200, 300 and 400 freezing-thawing cycles were performed. The experiment method, contents and result of strength and deformation of air-entraining after freezing-thawing cycle under biaxial compression were also introduced. The relationship between the strain corresponding to peak stress and cycle of freezing-thawing as well as the relationship between compressive strength and cycle of freezing-thawing were analyzed. The failure criterion of air-entraining concrete under biaxial compression was established.

Investigation of Free Volume Size and Mechanical Properties for PolymethylMethacrylate/Organic Rectorite Composites by PALS

2011 ◽  
Vol 233-235 ◽  
pp. 1868-1871
Author(s):  
Wei Zhou ◽  
Yan Sheng Gong
Keyword(s):  
Mechanical Properties ◽  
Free Volume ◽  
Atomic Scale ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Scale Free ◽  
Bending Modulus ◽  
Weight Content ◽  
The Relationship ◽  
Volume Size

PolymethylMethacrylate (PMMA) composites with different weight content of organic rectorite (OREC) are prepared via melt blending. The results of X-ray diffraction (XRD) show that the layer distance of OREC is much larger than that of the pristine rectorite. SEM images reveal that the OREC filler has been well dispersed in matrix. With the addition of OREC, Bending modulus increased obviously. Ortho-positronium (o-Ps) lifetimes show that the free volume sizes of PMMA/OREC composites are larger than those of the PMMA matrix. The relationship between the atomic-scale free volume size and mechanical properties is preliminarily discussed in this work.

STRUCTURES AND MECHANICAL PROPERTIES OF MODULATED ZrB2/W AND ZrB2/WNx NANOMULTILAYERS

2010 ◽  
Vol 24 (01n02) ◽  
pp. 34-42 ◽  
Author(s):  
M. TAN ◽  
D. J. LI ◽  
G. Q. LIU ◽  
L. DONG ◽  
X. Y. DENG ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Significant Contribution ◽  
Layer Structure ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Composition Modulation ◽  
Ion Beam Assisted Deposition ◽  
Xrd Patterns

ZrB 2, W , WN x coatings and ZrB 2/ W , ZrB 2/ WN x multilayered coatings have been synthesized by ion beam assisted deposition at room temperature. X-ray diffraction (XRD), XP-2 surface profiler, scanning electron microscopy (SEM) and nano indenter were employed to investigate the influence of modulation periods and N + beam bombardment on microstructure and mechanical properties of the coatings. The low-angle XRD patterns and cross-sectional SEM indicate a well-defined composition modulation and layer structure of the multilayers. The multilayers with modulation periods ranging from 9 to 16 nm without N + bombardment possessed higher hardness and elastic modulus than the rule-of-mixtures value of monolithic ZrB 2 and W coatings. The highest hardness was 24 GPa. N + bombardment to growing multilayers gave a significant contribution to mechanical property enhancement. When modulation period is 9.6 nm, ZrB 2/ WN x multilayer with 200 eV N + bombardment reveals the highest hardness (30.2 GPa) and elastic modulus. This hardest multilayer also showed the improved residual stress and fracture resistance.

Mechanical Properties of Modified Epoxy/Rubber Concrete

2016 ◽  
Vol 859 ◽  
pp. 39-44 ◽  
Author(s):  
Xing Wang Shu ◽  
Ying Zhang
Keyword(s):  
Mechanical Properties ◽  
Strain Curve ◽  
Peak Stress ◽  
Rubberized Concrete ◽  
Stress Strain ◽  
Stage Transition ◽  
Modifier Content ◽  
The Relationship ◽  
Rubber Concrete ◽  
Modified Epoxy

To research the effect of a elastic modifier on the mechanical properties of epoxy/rubber concrete, series of epoxy/rubber concretes were prepared with different elastic modifier content, the relationship between elastic modifier content and stress-strain curve of epoxy/rubber concretes were investigated. Results show: as the increase of elastic modifier content, both the compressive and bending stress-strain curves of epoxy/rubber concretes experience a stage transition of elastic-elastoplasticity-plastic apparently; the slope in the rising and falling section of stress-strain curves are gradually decreased; the peak stress decrease while the corresponding strain and stain energy increase. Content of elastic modifier between 40pbw and 60 pbw is proposed in order to attain better properties of epoxy/rubber concrete. Compared with ordinary concrete and rubberized concrete, Improved epoxy/rubber concrete has better comprehensive mechanical properties and larger rubber content.

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