材料期刊网

COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOW FIELD IN HALL-HEROULT CELLS USING FINITE THOD

J. Li , W. Liu , Y.Q. Lai , null , null

金属学报(英文版)

Two full 3D steady mathematical models are developed by finite element method (FEM) to calculate coupled physics fields: the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.

关键词: coupled simulation , null , null , null , null

Wetting phenomena in CuZr-based glassy alloys/W system

Journal of Alloys and Compounds

The wetting behavior and interfaces of CuZr-based glassy alloys/W system were investigated by the sessile drop method. It was found that Cu(50)Zr(50)/W, Cu(47.5)Zr(47.5)Al(5)/W and Cu(40)Zr(44)Al(8)Ag(8)/W system had the final equilibrium contact angle around 18 degrees, 8 degrees and 3 degrees at corresponding experimental temperatures. Base on the scanning electron microscopy observing, no reaction product can be found at the interface of Cu(47.5)Zr(47.5)Al(5)/W and Cu(40)Zr(44)Al(8)Ag(8)/W, and some granular reaction products appeared along the interface of Cu(50)Zr(50)/W. The present work indicates that Cu(47.5)Zr(47.5)Al(5) and Cu(40)Zr(44)Al(8)Ag(8) bulk metallic glasses (BMGs) are appropriate for the fabrication of W reinforced BMGs matrix composite. (C) 2010 Elsevier B.V. All rights reserved.

关键词: Wettability;Diffusion;Composite;Metallic glasses;bulk metallic glasses;mechanical-properties;matrix composites;compressive plasticity;amorphous-alloys;behavior;tungsten;al;solidification;deformation

TiAl-W-Si合金中的偏析与析出相的分析电子显微术研究

于荣 , 贺连龙 , 程志英 , 朱静 , 叶恒强

金属学报 doi:10.3321/j.issn:0412-1961.2002.z1.140

用高空间分辨分析电子显微术研究了TiAl-W-Si合金中B2相的析出行为和元素W的分布.结果表明,α2/γ相界面台阶由于W的富集而成为B2析出相的择尤形核位置.B2相中,高达三分之一的Al原子被W原子置换,而在γ相中只固溶了很有限的W.另外,W也偏析在α2/γ和B2/γ相界面上.这些结果合理地解释了W对提高TiAl合金蠕变性能的显著作用.

关键词: 分析电子显微术 , TiAl , 析出相 , 偏析

Effect of Co and W additions on the structure and magnetic properties of Nd2Fe14B/alpha-Fe nanocomposite magnets

Journal of Physics D-Applied Physics

The effect of Co addition combined with W on the microstructure and magnetic properties of nanocomposite magnets with composition of (1 - x wt%)Nd8.55Fe84.49W0.60 B-0.636 + x wt% CO, prepared by mechanical alloying, has been investigated. The addition of W can increase the unit cell volume of soft and hard phases in nanocomposite: magnets, and cause the anisotropy field of the hard phase component to increase. Therefore, the addition of W can improve coercivity. On the other hand, addition of Co leads to a decrease of the grain size of the alpha-Fe soft phase component in nanocomposite magnets annealed at temperatures lower than 670 degrees C. It leads further to a decrease of the optimal annealing temperatures, an increase of the remanence and maximum magnetic energy product, and a slight decrease of the coercivity. With increasing the content of Co, the dependence of remanence J(r) on annealing temperature T-a changes from a convex shape, giving a maximum, to a monotonically decreasing one. These phenomena have been explained in terms of the variation of grain growth and exchange coupling between the grains, due to the addition of Co and W.

关键词: nd-fe-b;remanence enhancement;alloys;phase;microstructure;nb

METASTABLE CHARACTERISTICS OF β-W

HUANG Huimin CHEN Xinmin Central South University of Technology , Changsha , China HUANG Huimin Associate Professor , Department of Chemistry , Central South University of Technology , Changsha , China

金属学报(英文版)

The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.

关键词: tungsten , null , null , null

A_2W_3O_(12)(A=Y, Er, Ho, Yb)型稀土钨酸盐的高温XRD研究及结构精修

黄远辉 , 杨海涛 , 尚福亮 , 吴国根 , 汪晓

稀有金属材料与工程

用高温固相反应法制备出A_2W_3O_(12) 型稀土钨酸盐材料(A=Y,Er,Ho,Yb),用室温及高温XRD测定其在不同温度下的结构、晶胞参数及晶胞体积,并用TOPSA软件对其结构进行精修.发现除HO_2W_3O_(12)外,都具有较大的负热膨胀系数.据A. W. Sleight预测,HO_2W_3O_(12)具有较大的负热膨胀特性,但本实验却发现它并没有负热膨胀性,反而具有非常大的正热膨胀系数.

关键词: 稀土钨酸盐 , 高温XRD , HO_2W_3O_(12)

Al2O3含量对Al2O3/W复合材料合成的影响

韩兵强 , 李楠

材料科学与工程学报 doi:10.3969/j.issn.1673-2812.2003.06.020

以铝热法为基础制备了Al2O3/W复合材料,探讨了Al2O3含量对复合材料合成的影响.研究表明:主要物相为α-Al2O3、金属W.刚玉含量小于0 3时,温度影响不显著,大于0 3时,温度影响显著,有大量碳化物生成,且WC/W2C相对含量随Al2O3含量增加及煅烧温度的提高而增加.当刚玉含量为0 5mol时,有正交晶钨酸铝生成.随刚玉含量变化,金属钨分布从连续分布向弥散分布变化.连续分布的金属钨因被氧化铝包裹因此难以碳化,而弥散分布的金属钨则易于被碳化.

关键词: 铝热反应 , 相组成 , 显微结构 , 碳化

Effect of W on structural stability of TiAl intermetallics and the site preference of W

Physical Review B

The effect of W on the structural stability of TiAl intermetallic systems and the site preference of W in B2 and L1(0) TiAl were studied based on first-principles calculations. It was found find that about 15 at. % W addition, in good agreement with experiment, is required to stabilize the B2 structure in a TiAl base alloy. W was predicted to occupy Al sites in the B2 phase, but Ti sites in the L1(0) phase. The B2-stabilizing effect of W and its site preference can be explained perfectly on the basis of the pseudogap effect and the strong covalent W-Ti bonding. The strong W-Ti bonding pairs are maximized when W occupies Al sites in B2 TiAl. But when W occupies Al sites in L1(0) TiAl, the W-Ti bonding is weakened by the existence of Al in the alternating (002) plane, which can, however, strengthen the in-plane W-Ti bonding when W occupies Ti sites.

关键词: gamma-titanium aluminides;electronic-structure;microstructure;deformation;systems;alloys

Mg掺杂AlInP限制层窗口结构高功率(3.7 W) 660 nm AlGaInP宽面半导体激光器

马德营 , 李佩旭 , 夏伟 , 李树强 , 汤庆敏 , 张新 , 任忠祥 , 徐现刚

人工晶体学报

本文采用低压金属有机化学气相沉积系统(LP-MOCVD)生长出Mg掺杂压应变分别限制多量子阱结构的AlGaInP/GaInP 660 nm LD外延材料,制作出腔长1000 μm、条宽150 μm的宽面半导体激光器.采用选择性Zn扩散在管芯两端面区制作出透明窗口结构来提高器件的腔面光灾变阈值(COD).透明窗口结构激光器最大连续输出功率为3.7 W,是正常结构的激光器COD饱和功率的4.4倍.激光器的特征温度T0为68 K,热阻为4.6 K/W.在热沉温度为20 ℃时进行了500 mW恒功率老化,老化时间为1000 h.

关键词: 窗口结构 , Zn扩散 , 热阻 , AlGaInP , 半导体激光器

降低IF钢w(O)的工艺研究

王雄

钢铁研究 doi:10.3969/j.issn.1001-1447.2006.05.016

IF钢中w(O)的大小直接影响到成品板的表面质量.分析了武钢近年来IF钢w(O)偏大的生产现状,找到钢中w(O)、精炼处理前温度及钢包内炉渣等转炉冶炼、精炼及连铸工序对IF钢w(O)的影响,通过采用低氧钢生产工艺,使IF钢w(O)得到很好的控制.

关键词: IF钢 , w(O) , 转炉复吹