材料期刊网

PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-A1 FILMS BY VACUUM EVAPORATION

X.W.Shi , Z.Y.Liu , D.C.Zeng , C.M.Li

金属学报(英文版)

Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evap-oration parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10^-4Pa, resvectively.

关键词: vacuum evaporation , null , null

V-M(M=Li,Na,K,Sc,Ag)二元系的相图热力学研究

胡标 , 尹明 , 王庆平 , 闵凡飞 , 杜勇

兵器材料科学与工程

基于文献报道的实验数据,采用相图计算(CALPHAD:CALculation of PHAse Diagrams)方法对V-M(M=Li,Na,K,Sc,Ag)5个二元系进行相图热力学研究.通过热力学优化计算获得了一套描述液相、(V)、(Li)、(Na)、(K)、(αSc)、(βSc)和(Ag)相的热力学参数.V-Li、V-Na和V-K体系中的气相视为由组元V、Li、Li2、Na、Na2、K和K2混合的理想气体.与实验相图数据对比表明,获得的热力学参数能够准确地描述实验相平衡数据.

关键词: V-M(M=Li,Na,K,Sc,Ag) , CALPHAD方法 , 相图 , 热力学模型

Li1+xV3-yMyO8(M=Mo,P)高温阴极放电性能的研究

曹笃盟 , 李志友 , 周科朝

稀有金属材料与工程

采用固相反应法制备了Li1+xV3-yMyO8(M=Mo,P;0≤y≤0.4),研究了不同Mo和P含量对Li1+xV3O8相的影响,并首次对其进行了高温阴极放电性能的研究.结果表明:Mo和P掺杂量分别为y≤0.2和y＜0.2时可获得纯Li1+xV3O8相;Mo掺杂使Li1+xV3O8峰值电压提高0.3 V,比容量提高25%,嵌入的Li+量最高可达x=3.8;P掺杂(y≤0.20)对Li1+xV3O8的峰值电压和比容量影响较小.化学嵌锂实验也证实掺杂后的材料具有更快的Li+嵌入速度.

关键词: Li1+xV3O8 , 热电池 , 掺杂 , 比容量

Relationship between degeneration of M7C3 and precipitation of M23C6 in a cobalt base superalloy

Materials Science and Technology

The relationship between degeneration of the primary M7C3 carbide and precipitation of the secondary M23C6 carbide has been investigated in a cobalt base superalloy after 100 h aging at 850 degrees C. The results indicated that the primary M7C3 carbide could not transform in situ into the secondary M23C6 carbide. The M23C6 formed by a direct reaction between chromium and carbon atoms. The dissolution of M7C3 provided the precipitation of M23C6 with essential carbon, which acted as a carbon reservoir. Near M7C3, the chromium content is a controlling factor of M23C6 precipitation while away from it, the carbon content dominated the reaction. The precipitate free zone around M7C3 is attributed to chromium depletion which is inherited from the as cast condition. MST/4174

关键词:

Studies of the local structural parameters of rhombic V2+-V-M centers in MCl : V2+ (M = Li, Na) crystals from EPR data

Journal of Physics and Chemistry of Solids

In this paper, the high-order perturbation formulae of zero-field splitting D, E and g factors g(x), g(y), and g(z) for d(3) ions in rhombic symmetry are established by using a two spin-orbit (S.O.) parameter model in which the contributions due to both the S.O. coupling of the central d(3) ions and that of the ligands are considered. Based on these formulae, the local structural parameters of the rhombic defect centers V2+-V-M (i.e, the V2+ ion and a host metal ion vacancy V-M) in MCl:V2+ (M = Li, Na) crystals are estimated by calculating their EPR parameters. The results are discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词: inorganic compounds;crystal fields;defects;electron paramagnetic;resonance (EPR);ions

ON THE M_7C_3 IN Cr27 CAST IRON

LI Yuqing WANG Cirong GU Zhaofeng Research Institute of Daye Steel Works , Huangshi , China Senior Engineer , Research Institute of Daye Steel Works , Huangshi 435001 , China

金属学报(英文版)

Determination of(Fe,Cr)_7C_3 in Cr27 cast iron results about 30 v.-%.Minor Si and Mn are present.Sectional area of the M_7C_3 grains is 1—50μm~2.Combining matrix analysis of elec- tron diffraction pattern with calculated angle between plane traces,{011}twins and also {013}twins producing local environment for Ru_7B_3 are observed in the orthorhombic M_7C_3. A crystallographic model for M_7C_3 is proposed.

关键词: cast iron , null , null , null , null

Local structures of the tetragonal Gd3+-V-M and Gd3+-Li+ centers in perovskite fluorides

Radiation Effects and Defects in Solids

The zero-field splittings b(2)(o) of the tetragonal Gd3+-V-M and Gd3+-Li+ centers for Gd3+ ions in fluoroperovskite crystals have been studied on the basis of the superposition model in which the value of t(2) (b) over bar(2) is Obtained from the stress-dependence of EPR spectra for RbCaF3:Gd3+ crystal. From the studies, the local structures of both tetragonal centers in fluoroperovskite crystals are obtained and the results are discussed.

关键词: electron paramagnetic resonance;local crystalline structure;superposition model;Gd3+;fluoroperovskite;electron-paramagnetic-res;crystals;cr-3+-li+;spectra;epr

Zn-5%Al合金超塑性的m-C-δ(或m-k-δ)关系

刘勤 , 夏锄 , 刘晓东

金属学报

在170,190,210,230,250℃的温度下,采用3.7×10~2,7.4×10~2和1.1×10~(-1)min(-1)的应变速率(平均)对Zn-5%Al共晶合金的m-C-δ(或m-k-δ)关系曲线(简称m-δ关系曲线)进行了测定.所有的曲线均随应变的δ增加而快速上升.俟达到某一定的应变量(极限应变量δ1)后。开始缓慢下降并保持平稳直至断裂.Zn-5%A1共晶合金的m-δ关系曲线不存在k_(?)=k_I(k_(I 1),k_(I 2),k_(I 3),……)=k_F(或C_0=C_I(C_(I 1),C_(I 2),C_(I 3),……)=C_F=1)的简单情况.可应用m-δ方程式[4,5]对曲线上各点C值(包括所有的C_I和C_F值)进行计算.C值随δ值的增加成近似的直线上升.直线的斜率在极限应变(δ1)处突然减小.

关键词:

C60、M@C60(M=Si,Ge)富勒烯分子的压缩力学特性

沈海军

功能材料

采用基于Tersoff势的分子动力学方法,模拟了温度T=300、700和1100K下C60、M@C60(M=Si,Ge)富勒烯分子的对径压缩过程.根据模拟结果,讨论了温度T对3种富勒烯分子压缩力学特性的影响以及它们压缩力学特性的差异.研究表明,在300～1100K范围内,温度T对C60、M@C60(M=Si,Ge)分子压缩力学特性无显著影响;当压缩应变至8%～16%左右,各富勒烯分子在加载点处开始"塌陷",当压缩应变至28%～32%左右,各富勒烯达到承载极限;C60、Si@C60、Ge@C60分子依次具有由低到高的承载能力.

关键词: 富勒烯 , 分子动力学 , 力学特性 , 内嵌M@C60富勒烯

多孔球形Li2MnSiO4/C正极材料的制备及电化学性能

汪燕鸣 , 王广健 , 丁素芳

功能材料

采用湿法球磨-喷雾干燥法制备了多孔球形锂离子电池Li2MnSiO4/C复合正极材料。X射线衍射（XRD）表明合成的Li2MnSiO4具有正交结构,属于Pmn21空间群。扫描电镜（SEM）和透射电镜（TEM）显示粉体复合材料为直径10μm左右的球形团簇,由100nm左右的颗粒堆积而成,颗粒表面包覆1层大约3nm的碳层。电化学测试表明,在0.05和0.5C倍率下,Li2MnSiO4/C样品的首次放电容量分别为153和110mAh/g,50次循环后容量分别保持80%和66%。

关键词: 锂离子电池 , 硅酸锰锂 , 多孔球形 , 正极材料