材料期刊网

INVESTIGATION OF THE EFFECT OF TEMPERATURES ON TENSILE LOAD DROPS OF TITANIUM ALLOY

Z Zhang , ZH Tu , L.F. Li , L.Z. Zhaoand D. Jin (Cryogenic Laboratory Chinese Acaderw of Sciences , Beijing 100080 , China )H.J Lu (Beijing Institute of Aerospace Materials and Technology , Beijing 100076 , China)

金属学报(英文版)

Low temperature may greatly affect the mechanical properties of materials. Some in-teresting mechanical phenomena were detected at very low temperature. In this study,a multi-sample tensile installation was designed to study the plastic deformation be-havior for Ti-5Al-2.5Sn extra-low-interstitial (ELI) alloy at liquid helium temperature.The special geometrical instability phenomena in low temperature, serrated deforma-tion and multi necking, was studied in detail in this project. Slip and twinning were determined in the process of plastic fiow by SEM/TEM analysis. Efficts of temper-ature and sequential straining on load drops in tensile stress-strain curves were also studied. Optical measurement method was used to gauge the geometrical characteristic of multi-necking specimens. The sensitivity of partial thermoplastic deformation and the equivalency of low tempemture with high velocity of this material were studied by using micro-mechanics analysis.The criterion of geometrical instability has been discussed. A computer simulation of the low temperature instability of plastic fiow in Ti-5Al-2.5Sn ELI alloy has been carried out. A computer model has been established which links the hot dtffusion and the plastic fiow of hcp alloys under assumption that the tempemture is homogeneous within the specimen and that the heat exchange with the thermal bath is the control-ling step in the heat release. The computer simulation of the deformation curves as a function of several mechanincal, geometrical and thermal parameters provides a re-alistic description of the experiments. The experimental data available are discnssed in the light of the computer simulation model.

关键词: mechanical property , null , null

THE CALCULATION OF BaO ACTIVITIES IN BaO-BaF_2-Cr_2O_3 SYSTEM FLUXES USING SCHUHMANN METHOD

L.F. Li , Z.P. Chen , M.F. Jiang and W.Z. Wang(Department of Ferrous Metallurgy , School of Materials and Motallurgy , Northeastern University Shenyang 110006 , China)(The Technology Center , Baoshan Iron & Steel Complex , Shanghai 201900 , China)

金属学报(英文版)

The principle and steps for the calculation of component activities in fluxes using Schuhmann method are described. On the foris of Gibbs-Duhem equation and using Cr2O3 activities in BaO-BaF2-Cr2O3 system fiuxes, BaO activities at 1523 and 1673K are calculated, respectivelg,and the isoactivity diagrums of BaO are also obtained. The calculation results indicate that BaO activity increases with increasing its content in fiuxes, and decreaaes with the increase of Cr2O3 content at a given XBaO/XBaF2 ratio.

关键词: Shuhmann method fluxes , null , null

Li,K|F,Cl互易系熔盐溶液的分子动力学计算机模拟研究

邵俊 , 徐桦 , 陈念贻

金属学报

用分子动力学方法对Li,K?F,Cl系熔盐溶液进行了计算机模拟研究。计算了径向分布函数、偏克分子混合能等热力学性质以及Li~+,K~+,F~-和Cl~-的扩散系数。计算值与实验值大体符合。根据计算结果,讨论了熔盐溶液中离子和空孔分布的规律。

关键词: 碱卤化物熔盐 , molecular dynamics , computerized simulation

Effect of Li and Ti Additions on L■α(Al)+Mg_2Si Pseudobinary Eutectic Reaction

Shengxu ZHAO , Shunpu LI , Deqian ZHAO , Mingxiang PAN and Xichen CHEN(Institute of Physics , Chinese Academy of Sciences , Beijing 100080 , China)

材料科学技术（英）

Effect of Li and Ti additions on Lα(AI)+Mg2Si pseudobinary eutectic reaction in ternary Al-Mg-Si system has been investigated by thermoanalysis, directional solidification and metallographic techniques in this study. It has been found that Li addition causes decreasing of the volume fraction of Mg2Si, while a little amount of Ti causes to increasing, which is of a great importance to the adjustment of phase constitution and alloy properties. Doping components have little influence on the eutectic temperature.

关键词:

L12-Al3Li金属间化合物点缺陷浓度的第一原理计算

孙顺平 , 李小平 , 于赟 , 卢雅琳 , 臧冰 , 易丹青 , 江勇

中国有色金属学报

运用第一原理平面波赝势方法计算L12-Al3Li金属间化合物点缺陷的形成焓,并结合Wagner–Schottky模型,研究L12-Al3Li金属间化合物在523、673、823和1000 K时点缺陷浓度与成分之间的关系.结果表明:在这4个温度下,L12-Al3Li金属间化合物中Al空位浓度最小,Li空位浓度次之,Al反位和Li反位的缺陷浓度较大.Al反位和Li反位缺陷浓度在理想金属间化合物Al3Li化学计量比成分处基本相同,不过两种反位的缺陷浓度随着合金成分相对于化学计量比成分的偏离而变化显著,在富Al端Al反位缺陷浓度较大,在富Li端Li反位缺陷浓度较大.运用Arrhenius方程计算点缺陷的有效形成焓,结果显示Al反位和Li反位的有效形成焓较小且基本相同,Li空位次之,Al空位最大.

关键词: Al3Li金属间化合物 , 第一原理计算 , 点缺陷浓度 , 形成焓 , Wagner–Schottky模型

Theoretical studies of g factors and defect structures for cubic, tetragonal, and orthorhombic Fe+ Centers in alkali halides MX (M = Li, Na; X = F, Cl)

Communications in Theoretical Physics

The EPR g factors for cubic, tetragonal and orthorhombic Fe+ centers in alkali halides MX (M = Li, Na; X = F, Cl) are calculated from second-order perturbation formulas of g factors based on cluster approach for 3d(7) ions in three symmetries. From calculations, the g factors of these Fe+ centers in MX crystals are reasonably explained and the defect structural data for the tetragonal and orthorhombic Fe+ centers are estimated. The results are discussed.

关键词: crystal;and ligand-field theory;electron paramagnetic resonance;defect structure;atomic screening constants;spin-orbit interaction;superposition model;resonance-spectra;epr parameters;crystal-field;scf functions;ions;co2+

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

腐蚀科学与防护技术

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

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

腐蚀科学与防护技术

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

316L不锈钢在熔融LiCl-3%Li2O中的腐蚀行为

常晓亮 , 王旭 , 王兰芳 , 张俊善 , 祝美丽

机械工程材料 doi:10.3969/j.issn.1000-3738.2007.04.004

采用浸没法腐蚀试验研究了在真空及空气两种环境中316L不锈钢在700℃熔融LiCl-3%Li2O混合熔盐中的热腐蚀行为.结果表明:316L不锈钢在两种条件下的腐蚀产物均为LiCrO2,腐蚀质量损失均随时间的延长而增大;在真空条件下腐蚀质量损失明显小于空气条件下,氧分压对腐蚀行为的影响显著.

关键词: 316L不锈钢 , 熔盐 , 腐蚀

F^-离子对Li₂O-Al₂O₃-SiO₂系微晶玻璃晶化的影响

胡安民 , 梁开明 , 顾守仁

无机材料学报

采用差热分析(DTA),X射线衍射分析(XRD),扫描电镜(SEM等分析手段研究了F-离子对Li₂O-Al₂O₃-SiO₂系微晶玻璃形核和晶化的影响.结果发现,引入F^-离子使得玻璃的析晶峰值温度降低,玻璃的析晶活化能E降低,晶化指数n加大.引入F^-离子后,一方面促进了玻璃析晶和晶化,Li_xAl_xSi_1-xO₂固溶体析出以及Li_xAl_xSi_1-xO₂固溶体向β-锂辉石固溶体转变加快,晶化后的晶粒尺寸加大,析晶活化能E,晶化指数n与扫描电镜(SEM)分析一致.表明F-离子促进了玻璃晶化和离子扩散.

关键词: 差热分析 , glass-ceramics , nucleation , crystallization