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Molecular dynamics simulation of kink in 〈100〉 edge dislocation in body centred cubic iron

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chinese Science Bulletin 2007年第16期52卷 2291-2296页

作者： CHEN LiQun1,2,WANG ChongYu2,3,4 & YU Tao2 1 College of sciences,Central South University of Forestry & Technology,Changsha 410004,china 2 Central Iron and Steel Research Institute,Beijing 100081,china 3 Department of physics,Tsinghua University,Beijing 100084,china 4 international center for materials physics,chinese academy of sciences,shenyang 110016,china College of sciences Central South University of Forestry & Technology Changsha 410004 China Iron and Steel Research Institute Beijing 100081 China Department of physics Tsinghua University Beijing 100084 China international center for materials physics Chinese Academy of Sciences Shenyang 110016 China

Using the molecular dynamics method,we have constructed two kink models corresponding to the 〈100〉{010} and 〈100〉{011} edge dislocations (EDs) in body centred cubic (bcc) Fe. It is found that the geometric structure of a kink depends on the type of edge dislocation and the structural energies of the atoms sites in the dislocation core region. The formation energies,migration energies and widths of the kinks in different types of EDs are calculated. The results show that formation and migration of the kink in the 〈100〉{010} edge dislocation are difficult. The 〈100〉{011} edge dislocation moves primarily through kink nucleation,rather than kink migration.

关键词：分子动力学边缘位移铁纽结结构

Distinguishing the authenticity of anti-freeze liquid and brake fluid by terahertz time-domain spectra technology

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Distinguishing the authenticity of anti-freeze liquid and br...

Unusual Behaviour of Dislocation Velocity Exponent in Dislocation Multiplication Model

中国光学学会2010年光学大会

作者： ZHU Shou-ming 1,ZHAO Kun 1,2,4,TIAN Lu 1,ZHAO Song-qing 1,ZHAO Hui 1,BAO Ri-ma 1,MIAO Qing 1,ZHOU Qing-li 3,SHI Yu-lei 3,ZHAO Dong-mei 3,ZHANG Cun-lin 3 1.School of Science,china University of Petroleum,Beijing 102249,china 2.State Key Laboratory of Heavy Oil Processing,china University of Petroleum,Beijing 102249,china 3.Beijing Key Laboratory for Terahertz Spectroscopy and Imaging,Key Laboratory of Terahertz Optoelectronics,Ministry of Education,Department of physics,Capital Normal University,Beijing 100048,china 4.international center for materials physics,chinese academy of sciences,shenyang 110016,china.

Terahertz time-domain spectra （THz-TDS） technology is a new kind of coherent far infrared spectroscopy measurement technique based on the femtosecond *** optical property and spectroscopy of methanol,anti-freeze liquid and brake fluid are studied based on the THz-TDS in the terahertz *** whether methanol exists in anti-freeze liquid or brake fluid by Using THz-TDS technology is crucial to its *** room temperature,the time-domain spectra and the absorption spectrum in the 0.2-2.5 THz region of these samples are obtained in the environment full of *** Results show that methanol,anti-freeze liquid and brake fluid have significant different absorption spectra in this wave *** absorption peaks of methanol are located at 0.72 THz and 0.35 THz and the main absorption peaks of anti-freeze liquid and brake fluid are located at 0.62 ***-TDS Technology can distinguish minor differences in structure and can be applied to physical testing and *** provides a new experimental method for the identification of the organic chemical products and the study of spectrum more wide.

关键词： terahertz methanol anti-freeze liquid brake fluid

来源： cnki会议评论

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Journal of materials Science & Technology 1998年第3期14卷 215-218页

作者： Xaowei WANG(international Centre for materials physics, Institute of Metal Research, chinese academy of sciences,shenyang 110015, china) international Centre for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

The chaotic behaviour of dislocation multiplication process was investigated. The change of Lyapunov exponent which is used to determine the stability of quasi-periodic and chaotic behavior as well as that of equilibrium points, and periodic solution was reported by using an iteration model of dislocation multiplication. An unusual behavior of Lyapunov exponent and Feigenbaum exponent which respond to the geometric convergence of orbit from bifurcation to chaos was shown by dislocation velocity exponent m and there is a distinction on the tendency of convergence for the dislocation multiplication model when it was compared with logistic map. It is reasonable for the difference to be analyzed from the materials viewpoint. (Edited author abstract) 9 Refs.

关键词： Unusual Behaviour of Dislocation Velocity Exponent in Dislocation Multiplication Model

Role of Edge and Screw Dislocations in Deformation of Metals

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Journal of materials Science & Technology 1995年第2期11卷 133-136页

作者： Chiwei LUNG(international Centre for materials physics, Institute of Metal Research,chinese academy of sciences, shenyang, 110015, china) Inst of Metal Research Shenyang China

It was widely accepted that the screw dislocation is responsible for the strong temperature dependence of the yield stresses observed in bcc metals. In this paper, we show the role of edge dislocations in the deformation of metals and point out that in some cases, its main contribution to the plastic flow behaviour cannot be ignored.

关键词： Crystal structure

Multirange Fractals in materials: Applications to Fracture and Mechanical Alloying under Ball Milling

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Journal of materials Science & Technology 1997年第4期13卷 255-259页

作者： Chiwei LUNG(international Centre for materials physics, Institute of Metal Research,chinese academy of sciences, shenyang 110015, china) international Centre for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

A new model of multirange fractals is proposed to explain the experimental results observed on the fractal dimensions of the fractured surfaces in materials. A new explanation to the Williford's multifractal curve on the relationship of fractal dimension with fracture properties in materials has been given. It shows the importance of fractorizing out the effect of fractal structure from other physical causes and separating the appropriate range of scale from multirange fractals. Mechanical alloying process under ball milling as a non-equilibrium dynamical system has been also analyzed.

关键词： Ball Applications to Fracture and Mechanical Alloying under Ball Milling Multirange Fractals in materials

Effects of Positron Diffusion and Its Application in Composite System

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Journal of materials Science & Technology 2000年第3期16卷 311-314页

作者： Jian JIANG, Xinzhang ZHOU and ChiWei LUNG (international center for materials physics, Institute of Metal Research, chinese academy of sciences, shenyang 110015, china) international center for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

The effects of positron diffusion on the measured S parameter have been investigated by a point-source diffusion model and a δ function method. Firstly, the theoretical analyses of the effects are presented for the samples of a homogeneous semi-infinite medium and a film of definite thickness. Then the results are used to analyze the S parameters in several composite systems and interface models.

关键词： Effects of Positron Diffusion and Its Application in Composite System

Dislocation Velocity Exponent and the Strain Rate

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Journal of materials Science & Technology 2001年第3期17卷 363-366页

作者： Hongyan LIU and Xiaowei WANG international center for Material physics, Institute of Metal Research, chinese academy of sciences, shenyang 110016, china E-mail: liu@*** Intl. Cent. for Mat. Phys. Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

The process of dislocation multiplication has been described hv chaos theory, trying to reveal the connection between the microstructures on the mesoscopic scale and the mechanical properties of material on the macroscopic scale. The relationship between the dislocation velocity exponent and the maximum of strain rate is given. The results obtained from logistic equation with exponent and the dislocation multiplication dynamic equation are compared. A scale law in one-dimension-map model with exponent is shown when the exponents of equations are changed.

关键词： Dislocation Velocity Exponent and the Strain Rate

Universality and Specificity of Fractal Dimension of Fractured Surfaces in materials

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Journal of materials Science & Technology 2000年第1期16卷 1-4页

作者： Chiwei LUNG and Shenggang WANG (international Centre for materials physics, Institute of Metal Research, chinese academy of sciences, shenyang 110015, china) international Centre for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

After calculation on the fracture angles under various conditions of specific surface energies with different symmetry operations of rotation, the complicated behavior of dependence of fractal dimension on the structure of crystal is shown. It is found that the crack propagates along the weakest crystal plane no matter what the direction of the maximum stress is if the anisotropy is sufficiently strong; and then, the fractal dimension of the fractured surfaces might be determined by the approximate fractal structure already existed in the material. Specificity of the fractal dimension of fractured surfaces would be easy to appear in this case. Reversely, the crack propagates along the direction of the maximum stress no matter what direction of the weakest crystal plane is if the anisotropy is sufficiently weak. Universality of the fractal dimension of fractured surfaces would be possible to appear in this case. In many real materials, universality and specificity of the materials are associated. The fractal dimension measured may more or less be influenced by the structure of materials and it shows its universality through the specificity of materials.

关键词： Universality and Specificity of Fractal Dimension of Fractured Surfaces in materials

Effects of Distribution of Induced Defects on Positron Diffusion

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Journal of materials Science & Technology 2000年第1期16卷 73-75页

作者： Xinzhang ZHOU, Jian JIANG and Chiwei LUNG (international center for materials physics, Institute of Metal Research, chinese academy of sciences, shenyang 110015, china) international center for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

The effects of distribution of induced defects on the positron diffusion was studied by using the point-source diffusion model and 6 function method.

关键词： Effects of Distribution of Induced Defects on Positron Diffusion