材料期刊网，材料期刊，材料类期刊，材料期刊投稿

THERMAL STRUCTURAL DISORDER AND MELTING TRANSITION IN HIGH-ANGLE GRAIN-BOUNDARY: A MOLECULAR-DYNAMICS STUDY

S.J. Zhao , Y.C. Wang , J.Q. You , Q.B. Yang , L.G. Zhou and H.Q. Ye (Department of Physics , Xiangtan University , Xiangtan 411105 , China)(Laboratory of Atomic Imaging of Solids , Institute of Metal Research , The Chinese Academy of Sciences , Shenyang 110015 , China)(Department of Materials Science , Northeastern University , Shenyang 110006 , China)

金属学报(英文版)

A structural transition in the fcc ∑=5 (120)/[001] high-angle tilt grain-boundary(GB)is investigated by molecular-dynamics simulation. The calculations have been performed at various temperutures and the thermodynamic melting point Tm of the model system is determined by using a many-body potential fitted to copper. A thermal disorder transition in the GB region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experiment results and theoretical prediction.Moreover we also observed that melting initiated at the interface and then propagated into the bulk quickly at or above Tm.

关键词: moleculandynamics , null , null

INTERFACIAL STRUCTURAL RELATIONSHIP BETWEEN S'(Al_2CuMg) AND ALUMINUM

Q.B. Yang , G.J Shifietand E.A. Starke , Jr(Department of Physics , Xiangtan University , Xiangtan 411105 , China)(Depedment of Materials Science and Engineering , University of Virginia , Charlottesvil1e , VA22903 , USA)

金属学报(英文版)

A clear understanding of the structure of the S precipitates which are present in Al-Li-X alloys is verp imporiant because the S -phase decreases the localization of strainand promotes less anisotropic properties during deformation. The close structural re-lationship between the S-phase and the Al matrix and their possible intedece bound-ary strvcture are described in detail. The proposed model is in good agreement with::::rimental obserwations. The dynamics Of the phase trunWrmation and possiblermation mechani8ms for the S,-phase are alSo proposed.

关键词: Al-Li alloy , null , null

PHASE EXTENSION AND STRUCTURE ANALYSIS BY THE MAXIMUM ENTROPY METHOD

G.B.Hu and Q.B.Yang (Department of Physics , Xiangtan University , Xiangtan 411105 , China)(Beijing Laboratory of Electron Microscopy , Center for Condensed Matter Physics , The Chinese Academy of Sciences , P. O. Box 2724 , Beijing 100080 , China)

金属学报(英文版)

Excellent results are obtained in structure analysis with jew phases of structure factors by the maximum-entropy method (MEM) for CaGaN PbCO3 and ReBe22 single crystals. The computation time and memory space are minimized by symmetry operations so that structure analysis by the MEM can be carried out with a personal computer.

关键词: maximum entropy method , null , null , null

ALTERNATIVE DESCRIPTION OF THE SHEAR PLANE OF THE R-PHASE

Q.B. Yang and J.A. Wert (Dept. of Physics , Xiangtan University , Xiangtan 411105 , China)(Dept. of Materials Science & Engineering , University of Virginia , Charlottesville , VA 22903-4402 , USA)

金属学报(英文版)

A high density of {110} shear planes has been observed in the R-phase (Al5CuLi3)following phase transformation from the AlCuLi icosahedral Phase. The Present paper shows that the atomic arrangement in the vicinity of the shear planes can be described as a two-dimensional periodic array of atom clusters with 5-fold symmetry. This result is obtained by projecting along the [1. 618...01] direction of the atomic positions from four adjacent lattice planes that cross the shear plane. The projection reveals that the shear plane consists of pentagonal arrangements of double triacontahedra,each pentagon incorporating 606 atoms. The calculated diffraction pattern from the pentagon has approximate 10-fold symmetry characteristic of a quasicrystal.

关键词: : shear plane , null , null