材料期刊网

HIGH STRAIN RATE SUPERPLASTICITY OF DISCONTINUOUS CERAMIC FIBER REINFORCED ALUMINUM COMPOSITES

T. Imai , L. Geng , J. F. Mao and I. Tochigi 1) National Industrial Research Institute of Nagoya , 1-1 Hirate-cho , Kita-ku , Nagoya , 462-8510 , Japan 2) School of Materials Science & Engineering , Harbin Institute of Technology , Harbin 15001 , China 3) Kanagawa High-Technology Foundation , Kanagawa Science Park , 3-2-1 , Sakado , Takatsu-ku , Kawasaki , Kanagawa 213 , Japan

金属学报(英文版)

β-Si3N4 whisker reinforced aluminum composites was fabricated by squeeze casting before extrusion and an effect of content of Mg on the High Strain Rate Superplastic- ity (HSRS) were investigated, The optimum temperature of the composites at which maximum total elongation is obtained decreases according to magnesium content and the β-Si_3N_4w/Al-3Mg exhibits the total elongation of about 200% at the strain rate of 10~(-1) s~(-1) and at 853-858 K, although the β-Si_3N_4w/Al-0Mg composite shows about 100% elongation at the strain rate of about 1×10~(-1) s~(-1) at 903-913 K. Optimum strain rate of the composites fabricated by squeeze casting was about 1×10~(-1) s~(-1) but TEM observation indicates that the β-Si_3N_4w/Al-Mg has a fine grain of about 2- 3μm and that the whisker might no react with Mg at the interfaces, although the β-Si_3N_4 whisker react with aluminum matrix.

关键词: high strain rate superplasticity , null , null

THE CHANGING ROLE OF THE NATIONAL LABORATORIES IN MATERIALS RESEARCH

WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate , Lawrence Livermore National Laboratory , Livermore , CA 94551)

金属学报(英文版)

The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.

关键词: : U.S. Materials Science. U.S. National Laboratories and Facilities , null

Industrial Research on Broadening of Slab in Continuous Casting Process

FU Jian-xun , LI Jing-she

钢铁研究学报(英文版)

The broadening of slab was investigated on the basis of several industrial manufactures of continuous casting. The results show that slab broadening commonly exists in the process of continuous casting. It is found that there are few reports on it until now. In order to find out the reasons of slab broadening, we checked the effect of change of mold size, excepting technological parameters, conditions of soft reduction, and contraction of roll gap on slab broadening. Our examinations exclude the possibility of change of mold size, excepting technological parameters to be the causes of broadening of slab. The broadening of slab probably results from the static pressure of molten steel and the force from driving rolls. At the same time, online observations on three kinds of steel in the process of continuous casting reveal that the average objective ratio of slab broadening ranges from 1.27 % to 3.00 %, and even arrives at 4.4 %. In addition, the width of mold and formulas of calculating the broadening of slab was deduced.

关键词: continuous casting;slab;broadening;industrial investigation

Theoretical calculations of thermal shifts and thermal broadenings of sharp lines and zero-field splitting for ruby. Part I. Thermal shifts of R-1 and R-2 lines

Journal of Physics and Chemistry of Solids

A new theory of spectral thermal shifts (TS) has been developed. For the first time, by taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI), all the levels and the admixtures of wavefunctions within d(3) electronic configuration, the microscopic expressions for all the parameters in Raman, neighbor-level and optical-branch terms of TS due to EPI have been derived; their values for the R-1, R-2 and ground levels of ruby have been evaluated; the contributions to TS from thermal expansion have also been calculated; and then, the unified calculation of the TS of R-1 and R-2 lines and zero-field splitting (ZFS) for the ground state and the thermal broadenings of R, R' and B line-groups have successfully been accomplished. It is found that the contributions from the second-order term of EPI Hamiltonian H-(2) are dominant in Raman terms of R-1 and R-2 lines; the optical-branch terms play an important role in TS and increase rapidly with temperature and the ones of R-1 and R-2 lines have opposite signs due to the effects of neighbor levels; the neighbor-level terms are very important and it is the admixtures of wavefunctions caused by Coulomb interaction between d electrons and/or trigonal-field and/or spin-orbit interactions that make them nonzero; the contributions to TS from thermal expansion are also important. (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词: crystal fields;optical properties;phonons;electronic structure;thermal expansion;diamond-anvil cell;entire energy-spectrum;r-line;pressure;measurement;temperature;spectroscopy;calibration;dependence

双相合金Mg-8Li-1Al的等通道转角挤压 I.挤压过程中的变形方式

刘滕 , 张伟 , 吴世丁 , 姜传斌 , 李守新 , 徐永波

金属学报

以X射线衍射分析术为主要分析手段, 探讨了双相合金Mg-8Li-1Al(质量分数, %)在等通道转角挤压(ECAP)变形过程中的变形方式. α相在第1道次ECAP过程中主要的变形方式是{1011}<1012>孪生, 在随后道次的ECAP过程中主要变形方式为位错滑移, 变形方式的转让变主要是由于ECAP造成的组织细化效应; 对于β相, 各道次ECAP的主要变形方式均为位错滑移.

关键词: 双相合金Mg-8Li-1Al , null

Research and development of carbon materials for electrochemical capacitors I. Electrochemical capacitors

新型炭材料

Electrochemical capacitors (ECs) store energy in eletric double-layers formed along the interface of electrode material and electrolyte, this produces an extremely large capacitance compared with the traditional capacitors. The fundamental principles of electrochemical capacitors are briefly introduced, and the key materials used like electrode materials, electrolytes, separator and current collector materials are summarized. Electrochemical capacitors with pseudocapacitance, such as metal oxides, polymers and hybrid capacitors, are also discussed. The characteristics, possible application fields, the development state, the future R&D prospects for electrochemical capacitors are highlighted.

关键词: electrochemical capacitors;supercapacitors;storage of electric energy;principles

Mg-14Li-1Al-0．1Ce合金在卤素溶液（NaX，X=F，C1，Br和I）中腐蚀行为的研究

马毅斌 , 李宁 , 黎德育 , 张密林 , 黄晓梅

腐蚀学报（英文）

用电化学方法研究了Mg-14Li-1Al-0．1Ce合金在卤素溶液（NaX，X=F，C1，Br和I）中的腐蚀行为并用失重法测定其腐蚀速率，用扫描电镜（SEM）观察腐蚀后的表面形貌，利用XRD检定腐蚀产物的相组成．结果表明，合金在卤素溶液中的腐蚀速率由低到高的顺序是：NaF〈NaI〈NaBr〈NaCl．经过48h腐蚀后，合金在NaCl、NaBr和NaI溶液中的腐蚀产物层的组分为Mg（OH）2，Li3Mg7和Li0.92Mg4.08，而在NaF溶液中的腐蚀产物层的组分为Li3Mg7和Li0．92Mg4．08．此外，合金在NaF溶液中的电化学活性非常低，出现了钝化现象．电化学阻抗谱表明合金腐蚀产物层不能起到防止基体腐蚀的作用．

关键词: 镁锂合金 , 腐蚀 , 卤化钠 , EIS , XRD

Mg-14Li-1Al-0.1Ce合金在卤素溶液(NaX,X=F, Cl, Br和I)中腐蚀行为的研究

马毅斌 , 李宁 , 黎德育 , 张密林 , 黄晓梅

腐蚀学报（英文）

用电化学方法研究了Mg-14Li-1Al-0.1Ce合金在卤素溶液(NaX, X=F, Cl,Br和I)中的腐蚀行为并用失重法测定其腐蚀速率, 用扫描电镜(SEM)观察腐蚀后的表面形貌, 利用XRD检定腐蚀产物的相组成.结果表明, 合金在卤素溶液中的腐蚀速率由低到高的顺序是:NaF<NaI<NaBr<NaCl. 经过48 h腐蚀后, 合金在NaCl、NaBr和NaI溶液中的腐蚀产物层的组分为Mg(OH)₂,Li₃Mg₇和Li_0.92Mg_4.08,而在NaF溶液中的腐蚀产物层的组分为Li₃Mg₇和Li_0.92Mg_4.08. 此外, 合金在NaF溶液中的电化学活性非常低, 出现了钝化现象.电化学阻抗谱表明合金腐蚀产物层不能起到防止基体腐蚀的作用.

关键词: 镁锂合金 , corrosion , sodium halide , EIS , XRD

TiAl ALLOYS FOR INDUSTRIAL USE

KEIZO HASHIMOTO(Advanced Technologies Research Laboratories Nippon Steel Corp.1618 Ida Nakahara-ku Kawasaki 211 JAPAN)

金属学报(英文版)

Gamma titanium aluminide (γ-TiAl)intermetallic compounds are spotlighted as lightweight heat-resistant materials, and have been investigated extensively to aiming commercial use.Fundamental approaches in which phase diagrams of Ti -Al -Cr and TiAl -Nb have been studied based on the experimental data and calculations , have been performed in the national project For industrial approach, ingot process and direct casting process have been developed to provide sheet form of TiAl. By these approaches, γ-TiAl base ,intermetallic compounds show a great possibility to apply in the variety of fields .However, a more detailed understanding of phase equilibrium in Ti-Al -X and the relationship between the mechanical properties and microstructure will be necessary

关键词: : TITANIUM ALUMINIDE , null , null , null , null

关于倍频的部分相干光理论:I.定义与描述

赵珂

量子电子学报 doi:10.3969/j.issn.1007-5461.2001.05.020

本文基于部分相干光理论重新考察并描述了晶体的倍频过程.概括地说,本文用入射基波传播经基矢为a、b的晶格定义出晶体输出面中两点p2和p1,然后计算该两点2ω0光振动分量之间的互相干函数,在互相干函数的计算中采用了频域变换技术,通过引入定义量p(ω)及其求解,最后确定了由部分相干光理论所重新表述的入射基波激励产生的二次谐波的辐射强度分布的理论描述.

关键词: 倍频 , 二次谐波 , 部分相干光理论