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Solitary Magnon Localization in Antiferromagnet RbFeBr_3

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Journal of materials Science & Technology 1994年第3期10卷 225-228页

作者： Wuming LIU and benlian zhou(international centre for materials physics, institute of metal research, academia sinica, shenyang, 110015, china)Liming GUO(Dept. of Mathematics, institute of Yunnan Nationality, Xunming, 650031, china) Inst of metal research Academia Sinica Shenyang China

Introducing the Dyson-Maleev transformation. the coherent state ansatz and the time-dependent variation principle, we obtain two partial different equations of motion from Hamiltonian. Employing the method of multiple scales. we reduce these equations into the envelope function equations and force the amplitude function to satisfy a nonlinear Schrodinger equation. Using the inverse- scat-tering transformation, we obtain the single soliton solution and discuss the solitary magnon localization in antiferromagnet RbFeBr3

关键词： Rev Solitary Magnon Localization in Antiferromagnet RbFeBr3

Intrinsic Localized Modes in an Order-parameter-preserving Antiferromagnet

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Journal of materials Science & Technology 1993年第2期9卷 148-152页

作者： Wuming LIU+ Shaoyun FU benlian zhou, international centre for materials physics, institute of metal research, academia sinica, shenyang, 110015, china

Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.

关键词： intrinsic localized mode antiferromagnet magnon

Theoretical Prediction of Strength of Composite with Fractal-tree Structure Fibers

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Journal of materials Science & Technology 1993年第6期9卷 400-404页

作者： Shaoyun FU Wuming LIU benlian zhou Chiwei LUNG international centre for materials physics,institute of metal research,academia sinica,shenyang,110015,china

Theoretically;the strength of composite with branched fibers is predicted to be greater than that of composite with plain *** effects of the branching angle of the fiber,and the snubbing friction between the fiber and the matrix at the fiber branching point and the branching step's number of the fiber on the strength of the composite with branched fibers have been *** has been shown that the strength of the composite increases with branching angle,the snubbing friction and the branching step's number.

关键词： composite fiber fractal-tree structure

INVESTIGATION OF BEHAVIOUR OF B IN Ni_3Al ALLOYS BY POSITRON ANNIHILATION TECHNIQUE

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Acta metallurgica sinica(English Letters) 1993年第2期6卷 125-128页

作者： DENG Wen XIONG Liangyue LONG Qiwei international centre for materials physics institute of metal research,academia sinica,shenyang,chinaWANG Shuhe GUO Jianting institute of metal research,academia sinica,shenyang,china institute of metal research,academia sinica,shenyang 110015,china Inst of metal research Acad Sinica Shenyang China

The behuviour of B atoms added to mono-and poly-crystalline Ni_3AI alloys has been investi- gated hy positron annihilation technique(PA T).If the additive of B was less than 1.37 at-%, some of B atoms solid-solutioned interstitially into matrix and distorted the lattice,thus the lifetime (τ) of positron (e^+) Or matrix dilated:the others of them segregated on vacancy-like defects and formed "filling effect",thus the mean lifetime (τ)and S parameters *** B added was increased up to 2.22 at-%,more defects having larger free volume were induced by horide eutectic occurred along grain boundaries and grain interior,thus the τ in vacancy-like defects.τ and S parameters increased remarkably.

关键词： Ni_3Al positron annihilation B additive defect

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

Unusual Behaviour of Dislocation Velocity Exponent in Dislocation Multiplication Model

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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

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

Some Further Considerations about the Theory of Elastic Stress Transfer from Partially Embedded Axially Loaded Fiber to Matrix

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Journal of materials Science & Technology 1993年第5期9卷 322-326页

作者： Shaoyun FU benlian zhou Chiwei LUNG international Center for materials physics,institute of metal research,academia sinica,shenyang 110015,china

In this paper the elastic stress transfer from the fiber to the matrix is analysed for fiber-reinforced composites when the fiber is loaded *** dependence of the elastic stress transfer on the as- pect ratio of the fiber,the volume fraction of the fiber,the fiber-to-matrix elastic modulus ratio and the Poisson's ratio of the fiber and the matrix has been shown in detail.

关键词： elastic stress transfer fiber composite