材料期刊网

EFFECT OF ROTATING MAGNETIC FIELD ON MACROSTRUCTURE OF A CENTRIFUGAL CASTING Al-1%Cu ALLOY

W.X. Han , X.H. Qin , D.Z. Li and K. Yang (Institute of Metal Research , The Chinese Academy of Sciences , Shengyang 110015 , China)

金属学报(英文版)

Rotating electromagnetic field is applied to the centrifugal casting, the macrostructure of centrifugal casting Al-1%Cu alloy stirred with driving or backing magnetic field are both examined. It is shown that both kinds of electromagnetic filed can enforce the columnar-equiaxed transition, the driving one decrease the tendency of porosity occurring due to the increase in the bulk liquid pressure. Stirring with braking electromagnetic field produces the mixture of outer fine grains and inner coarse grains in the casting, this is analyzed to be contributed to the differences both in electric conductivity and density between the crystal and the melt, as well as skin effects.

关键词: centrifugal casting , null , null , null

HAN液晶盒中开关时间对形变场弛豫过程的影响

李晓吉 , 郑桂丽 , 张志东

液晶与显示 doi:10.3788/YJYXS20132801.0025

在HAN液晶盒撤掉外加电压的过程(即弛豫过程)中,假定电压的开关时间为有限的,把电压处理为时间的指数衰减函数.在这一假定下,对撤掉外加电压后HAN液晶盒中指向矢的分布情况进行研究,得到了对HAN液晶盒的弛豫过程有影响的电压开关时间的范围.

关键词: HAN液晶盒 , 有限开关时间 , 驰豫过程 , 动力学理论

Thermal transport properties and electronic structure of W-doped rubidium blue bronzes Rb(0.3)Mo(1-x)W(x)O(3) (x=0, 0.001, 0.003, 0.005)

Physica B-Condensed Matter

The thermoelectric power (TEP), electrical resistivity and X-ray photoemission spectrum (XPS) of the W-doped rubidium blue bronzes Rb(0.3)Mo(1-x)W(x)O(3) (x=0, 0.001, 0.003, 0.005) were investigated. It is shown that the Peierls transition is suppressed with the increase in the concentrations of the doped W ions. The sign change of the TEP was observed for all the samples. At low temperature below the Peierls transition, the W-doping makes the obvious decrease in the absolute values of TEP, especially for Rb(0.3)Mo(1-x)W(x)O(3) (x=0.003, 0.005). Furthermore, as compared with the pure blue bronzes, the enlarged difference between Peierls transition temperature (T(p)) and the sign changed temperature (T(s)) in Rb(0.3)Mo(0.999)W(0.001)O(3) bronzes was observed and discussed in detail. (C) 2010 Elsevier B.V. All rights reserved.

关键词: Charge density wave;Blue bronze;Thermoelectric power;Resistivity;charge-density-wave;thermoelectric-power;oxide bronzes;k0.3moo3;transition;scattering;rb0.3moo3;state;impurities;k0.30moo3

Amorphous forming ability of Co-X(X=Cr, Mo, W)  magnetic thin films

Gaowu QIN

金属学报(英文版) doi:10.1016/S1006-7191(08)60117-9

Co-X(X=Cr, Mo, W) magnetic thin films were prepared by using DC magnetron sputtering, and their structures were examined by using X-ray diffraction (XRD). The amorphous forming ability (AFA) of the three alloy systems was discussed based on thermodynamic calculation and experiments. The results show that the Co-Mo thin films exhibit the largest AFA among them, and the Co-W thin films are condition-dependent amorphous while the Co-Cr thin films are hard to be amorphous, which is consistent with the thermodynamic calculation. The difference in AFA for the alloys of these three systems is finally ascribed to three main factors: differences in electronegativity, electron density and atomic size between Co and X elements.

关键词: Amorphous forming ability , Co-Cr , Co-Mo , Co-W

过渡金属元素 X（X ＝W，Mo，Cr）对 RuAl合金抗氧化性影响的机理

袁江 , 宋新华 , 孙甲尧 , 龚航

航空材料学报 doi:10.11868/j.issn.1005-5053.2016.1.001

基于密度泛函理论的第一性原理，通过计算 RuAl 合金氧化物 Al2 O3和 RuO2的氧化能，考察过渡金属元素 X （X ＝W，Mo，、Cr）加入到 RuAl 合金后的占位及对氧化物 Al2 O3和 RuO2的结构稳定性影响。研究表明：经过渡金属元素 X 合金化后，Al2 O3和 RuO2的氧化能均有所增大，增大 Al2 O3氧化能的顺序为：W ＞Mo ＞Cr；增大 RuO2氧化能的顺序为：Mo ＞Cr ＞W，且 RuO2氧化能增大幅度大于 Al2 O3。通过态密度、电荷密度等因素的分析，阐明了 W 对提高 RuAl 抗氧化性能的根本原因是降低了 Al-O 和 Ru-O 的共价键特性，增加了 Al-O 和 Ru-O 的离子键特性；金属元素 X（X ＝W，Mo，Cr）可阻碍 RuAl 金属化合物发生内氧化过程，有利于在 RuAl 表面层的横向方向上形成连续性致密的 Al2 O3氧化层。

关键词: RuAl , 第一原理 , 抗氧化性能 , 稳定性 , 氧化能

(Mo_(1-x),W_x)Si_2固溶体的价电子结构及其性能研究

彭可 , 易茂中 , 冉丽萍 , 葛毅成

稀有金属材料与工程

根据固体与分子经验电子理论(EET),利用平均原子模型对(Mo_(1-x),W_x)Si_2)固溶体进行价电子结构分析,并分别与MoSi_2和WSi_2基体进行比较.结果表明,随着x值的增加,(Mo_(1-x),W_x)Si_2固溶体的主干键络键能、最强键上共价电子数和共价电子总数百分比均逐渐增加,表明固溶体的熔点、硬度和强度均逐渐增加.

关键词: (Mo_(1-x) , W_x)Si_2固溶体 , 价电子结构 , EET理论 , 性能

电场诱导纳米结构HAN液晶盒中新型有序重构过程的描述

陈思博 , 王永超 , 周璇 , 张志东

液晶与显示 doi:10.3788/YJYXS20163109.0853

基于 Landau-de Gennes 理论，利用松弛迭代的方法，研究了包含－1/2向错线的混合排列(HAN)液晶盒中，平行于向错线的电场所诱导的结构转变。结果表明，盒厚固定时，电场诱导五种结构转变过程；电场固定时，盒厚变化产生三类结构转变方式。力曲线上的极小值确定了液晶系统发生结构转变的临界盒厚。

关键词: 有序重构 , Landau-de Gennes理论 , -1/2 向错 , 力曲线

X射线荧光测定复式碳化物中W、Ti、Ta、Fe方法研究

颜晓华 , 彭宇 , 苏明

硬质合金 doi:10.3969/j.issn.1003-7292.2015.04.008

复式碳化物是一种硬质合金行业和其他新材料行业广泛使用的原料,常用的复式碳化物由TiC、WC、TaC等固溶生成.本方法以m(Li2B4O7)∶m(LiBO2)=67∶33为熔剂制备复式碳化物的熔融玻璃片,采用Bruker公司的S8 Tiger型顺序式X射线荧光光谱仪和Spectra plus基体效应校正等软件,在熔融条件、标样的设置、转换系数的计算、仪器条件等方面进行探讨,建立了X射线荧光光谱仪测定复式碳化物中W、Ti、Ta、Fe的含量方法,方法分析测定范围(氧化物)W 25.55％～52.41％、Ti 8.89％～31.48％、Ta 15.03％～28.54％、Fe 0.032％～ 1.07％,结果表明,方法的精密度和准确度较好.

关键词: 复式碳化物固溶体 , 化学分析 , X射线荧光光谱 , W , Ti , Ta , Fe

电沉积Ni-W合金镀层的X射线光电子能谱分析

王宙 , 许光宇 , 王金玉 , 杨德庄

材料保护 doi:10.3969/j.issn.1001-1560.2002.04.013

采用X射线光电子能谱(XPS)对电沉积Ni-W合金镀层表面膜进行了分析.研究结果表明,Ni-W合金镀层表面存在一层薄的氧化膜,而钨的氧化作用远大于镍,Ni-W合金镀层中W含量的提高对耐蚀性起决定作用.

关键词: 电沉积 , Ni-W合金镀层 , X射线光电子能谱

X-ray powder diffraction data for Al-Cu-W phases

Powder Diffraction

Ternary Al-Cu-W alloys were investigated. The previously reported Al(3)Ti-type phase (space group 14/mmm) with the average composition Al(67)Cu(11.5)W(21.5) was found to have a=3.7296(4) angstrom and c=8.3797(10) angstrom. The ternary phase forming around Al(67)Cu(21)W(12) has a hexagonal structure with a=8.6594(13) angstrom and c=15.2677(21) angstrom. (C) 2011 International Centre for Diffraction Data. [DOI: 10.1154/1.3549770]

关键词: Al-Cu-W;powder X-ray diffraction;system