材料期刊网

Tension and Thickness Control Strategy Analysis of Two Stands Reversible Cold Rolling Mill

LIU Guang-ming , DI Hong-shuang , ZHOU Cun-long , LI Hong-cui , LIU Jiang

钢铁研究学报(英文版)

In order to lucubrate the rolling characteristic of the two stands reversible cold rolling mill and establish the tension and thickness control strategy, the steady-state characteristic simulating program was established using the steady-state continuous rolling theory. The influences of each factor on exit thickness under different tension control methods were analyzed. The results show that, the influence of the entry stand gap on exit thickness is significant and it changes little with different tension control methods. As a result, the entry stand gap can be used as the main control method of exit thickness, whereas rolling speed of any stand and roll gap of the exit stand can be used to adjust the inter-stand tension. The results are beneficial for thickness and tension control of the two stands reversible cold rolling mill.

关键词: two stand , reversible cold rolling , thickness , tension , control strategy

Van Hove奇异性、非电声作用与HgBa2Cun-1CunO2n+2+δ(n=1,2,3)系统的超导电性

张霞 , 苏希玉 , 侯芹英 , 侯艳丽

低温物理学报 doi:10.3969/j.issn.1000-3258.2008.03.011

考虑态密度的Van Hove奇异性和非电声作用,我们在BCS理论框架内研究了HgBa2Cun-1CunO2n+2+δ(n=1,2,3)系统的超导转变温度和同位素效应.结果表明,当同时考虑Van Hove奇异性和非电声作用时,可以更好地解释HgBa2Cun-1CunO2n+2+δ(n=1,2,3)系统的超导性质.

关键词: Van Hove奇异性 , 非电声作用 , 超导转变温度 , 同位素效应

Longitudinal magnetotransport in long-period semiconductor superlattices

Physical Review B

Longitudinal electron transport is investigated for a long-period semiconductor superlattice in the presence of a magnetic field applied along the growth direction of the superlattice. It is shown that the longitudinal magnetoresistance exhibits a complicated dependence on the magnetic-field strength. In contrast with the conventional Shubnikov-de Haas oscillations, the magnetoresistance shows periodic oscillations only in the region of low reciprocal magnetic field.

关键词: magnetoresistance

Studies on the spin-Hamiltonian parameters of CuN(6) clusters and their tetragonal distortions due to Jahn-Teller effect for Cu(2+) in trigonal M(1-propyltetrazole)(6)(BF(4))(2) (M = Zn, Fe) crystals

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

This paper reports the theoretical calculations for the anisotropic and isotropic spin-Hamiltonian parameters (g factors and the hyperfine structure constants) of tetragonal CuN(6) octahedral clusters due, respectively, to the static and dynamic Jahn-Teller effects for Cu(2+) ion in the trigonal M(=Zn, Fe) sites of M(1-propyltetrazole)(6)(BF(4))(2) crystals. The calculations are carried out using the high-order perturbation formulas based on a two-mechanism model, in which besides the contributions to spin-Hamiltonian parameters due to the crystal-field mechanism concerning the crystal-field excited states in the extensively used crystal-field theory, the contributions due to charge-transfer mechanism concerning the charge-transfer excited states (which are neglected in the crystal-field theory) are included. The calculated results are in reasonable agreement with the experimental values. From the calculations the tetragonal elongations Delta R= R(parallel to) R(perpendicular to) (where R(parallel to) and R(perpendicular to) denote the Cu-N distances parallel with and perpendicular to the C(4) axis) of CuN(6) octahedral clusters due to Jahn-Teller effect are obtained. The results are discussed. (C) 2010 Elsevier B.V. All rights reserved.

关键词: Electron paramagnetic resonance;Crystal- and ligand-field theory;Jahn-Teller effect;M(1-propyltetrazole)(6)(BF(4))(2) (M = Zn, Fe);Cu(2+);atomic screening constants;electron-paramagnetic-res;single-crystal;sulfate hexahydrate;charge-transfer;scf functions;epr;ions;field;copper(ii)

LONG-TERM CREEP AND RUPTURE PROPERTIES OF HEAT RESISTING STEELS AND ALLOYS

K.Yagi and F.Abe (National Research Institute for Metals , 1-2-1 Sengen , Tsukuba 305-0047 , Japan)

金属学报(英文版)

The present status of NRIM Creep Data Sheet Project and the recent activities of long-term creep and rupture studies on heat resisting steels are described. The project has been continued to produce long-term data such as 100 000h-creep rupture strength for 47 kinds of principal heat resisting steels and alloys, including welded joints. The long-term creep deformation behavior and microstructural evolution during creep have been shown to be complicated.

关键词: heat resisting steel and alloy , null , null

Twinning in Intermetallic Compounds Are Long Shear Vectors and/or Shuffles Really Necessary?

F.M.Chu David P.Pope Dept.of Materials Science and Engineering , University of Pennsylvania , Philadelphia , PA 19104 , USA

材料科学技术（英文）

In this paper the geometric description and general theory of mechanical twinning are reviewed, the twins in general lattices and superlattices are summarized, and the kinetic process by which mechanical twins form is revisited. A case study of mechanical twinning of HfV2+Nb, (cubic) Laves phase, is presented and the synchroshear of selected atomic layers is proposed to explain the physical process of twin formation. If the twins form in this way, then long shear vectors and / or atomicshuffles are not really necessary.

关键词: twin , null , null , null

A NEW METHOD FOR MEASURING LONG-TERM CREEP DEFORMATION IN A SMALL REGION

J.M. Gong , S.T. Tu , J. Xia and X. Ling (School of Mechanical Engineering , Nanjing University of Chemical Technology , Nanjing 210009 , China)

金属学报(英文版)

Creep deformation localization is generally found in structures at high temperamture,typically in weldments. As the heat affected zone (HAZ) in a weldment is very narrow, deformation in HAZ region can hardly be measured by conventional displacement gauge. A new method for measuring long-term local creep deformation was developed by quartz optical fiber and technique of digital image analysis. The creep deformations of base metal, weld metal and HAZ in weldments are thereby determined with crossweld specimens.

关键词: creep deformation , null , null , null

Long periodic structure in ZrO2-Y2O3 ceramics

材料科学技术（英文）

A new type of long periodic structure has been found in ZrO2-Y2O3 ceramics in annealed states. High resolution electron microscopy (HREM), selected area electron diffraction, and computer simulation have been used to reveal the presence of the long periodic structure. The unit cell of the long periodic structure consists of a cubic ZrO2 unit cell and L1(0)- like phase one.

关键词: ceramics;electron diffraction;electron microscopy;crystal structure;microstructure

Long Periodic Structure in ZrO2-Y2O3 Ceramics

Jiancun RAO , Yu ZHOU , Douxing LI

材料科学技术（英文）

A new type of long periodic structure has been found in ZrO2-Y2O3 ceramics in annealed states. High resolution electron microscopy (HREM), selected area electron diffraction, and computer simulation have been used to reveal the presence of the long periodic structure. The unit cell of the long periodic structure consists of a cubic ZrO2 unit cell and L10- like phase one.

关键词: Ceramics , null , null , null , null

Role of long-range elastic energy in relaxor ferroelectrics

Applied Physics Letters

The dipole configuration of relaxor ferroelectrics (RFs) is investigated by numerically solving the time-dependent Ginzburg-Landau equation based on the dipole defect model. The domain structure of RFs is revealed to consist of dipole ordered clusters embedded in the paraelectric matrix. We demonstrate that the role of long-range elastic energy in RFs is much less important than in normal ferroelectrics, although the shape of the dipole clusters depends on the elastic energy. Based on the numerical results, a phase diagram of temperature-defect density for RFs is constructed, which identifies four distinct phase regimes. (c) 2006 American Institute of Physics.

关键词: monte-carlo-simulation;dielectric-properties;computer-simulation;domain formation;defects;field;model;glass