材料期刊网

INTERNAL OXIDATION KINETICS & DIFFUSION MECHANISM OF OXYGEN IN Cu-Al SINTERED ALLOY

S.G. Tian , L.T. Zhang , H. M. Shao , L.J. Zou , T.F. Li , and H. C. Yang (Department of Materials Science , Shenyang Polytechnic University , Shenyang 110023 , China) (Corrosion Science Laboratory , Institute of Corrosion and Protection of Metals , Chinese Academy ofSciences , Shenyang 110015 , China) (Department of Materials Science , Northeastern University , Shenyang 110006 , China)

金属学报(英文版)

In this paper, internal oxidation kinetics and the diffusion mechanism of oxygen in sintered Cu-Al alloy have been studied by means of scanning electron microscopy,transmission electron microscopy and heat-weighting scales. The results show that the kinetic curves obey the parabolic law in the initial stage and are linear in the late stage.The oxygen atoms are mainly transported in the from of grain boundary diffusion and volume diffusion in the process of internal oxidation. The plastic deformation of Cu matrix around oxide particles increases the probability of [O] atoms moving in accordance with dislocation diffusion mechanism. Meanwhile, the activation energy and diffusion coefficient in the process of internal oxidation are evaluated by means of kinetic method so as to obtain the velocity equations of reacting interface moving in different stage.

关键词: : Cu-Al alloy , null , null

F-T合成校正综合动力学模型

滕波涛 , 常杰 , 万海军 , 鲁继青 , 郑绍成 , 刘亚 , 刘颖 , 郭小惠

催化学报

考虑了烯烃、醇与酸的再吸附及其非本征效应(烯烃、醇与酸在催化剂孔道中的扩散作用、物理吸附及溶解度效应)对产物分布的影响,推导了基于详细反应机理的亚甲基插入的烷基机理F-T合成校正综合动力学模型.利用文献数据对动力学模型进行了回归,获得了与文献报道结果相一致的动力学参数.由校正动力学模型计算的烷烃、烯烃、醇与酸产物分布及烯烃比、醇烃比及酸烃比与实验数据较好地吻合.动力学计算结果表明,在铁锰催化剂上,烷烃、烯烃、醇与酸生成的反应是平行竞争反应,烯烃、醇与酸在催化剂表面的再吸附及二次反应导致产物分布偏离了ASF分布.动力学研究还表明,相同碳数的醇与酸产物在催化剂表面上再吸附及二次反应的机会比相同碳数的烯烃大.通过比较相同碳数的烯烃、醇与酸的分子体积及沸点,指出了在铁锰催化剂上,低碳数的烯烃、醇与酸的再吸附及二次反应对产物分布影响的非本征效应中,烯烃、醇与酸的扩散阻力不是主导效应.

关键词: 费托合成 , 动力学模型 , 产物分布 , 烃 , 含氧化合物

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 HOMOGENIZATION TREATMENT UNDER AN ELECTRIC FIELD ON T_1 DISTRIBUTION AND MECHANICAL PROPERTIES OF 2091 Al-Li ALLOY

LIU Wei , CUI Jianzhong(Northeastern University , Shenyang , ChinaManuscript received 10 November 1994)

金属学报(英文版)

Homogenization treatment under an electric field increases the distributive homogeneity of the T1 precipitation and improves the yield strength of 2091 Al-Li alloy.

关键词: :homogenization treatment , null , null , null

Al-Li-Cu-Zr合金中T1相结构、形核和长大机制研究

卫英慧 , 贾连锁 , 胡兰青 , 许并社

稀有金属材料与工程

T1(Al2CuLi)相是Al-Li-Cu-Zr合金中的重要强化相.通过TEM在对T1相结构和形貌分析的基础上,构造了T1相的结构.T1相晶核以ABCBA的堆垛顺序,共由36个原子组成,其晶格常数a=0.495nm,c=0.933nm.与基体的位相关系为:{0001}T1∥{111}α,<>T1∥<110>α.合金中铜原子的偏聚降低了基体的层错能,从而为T1相依赖扩散层错形核提供了有利条件.T1相长大依赖于原子扩散和台阶滑移,是一种长程扩散控制的台阶机制.

关键词: Al-Li基合金 , 相变 , 时效 , T1相

Synthesis and superconductivity of Nd0.7Sr1.3Cu(O,F)(4-delta) with T-c=44 K

Physica C-Superconductivity and Its Applications

Superconducting cuprate fluorides Nd0.7Sr1.3Cu(O,F)(4-delta) with T-c = 44 K were obtained by solid phase fluorination of the T-structure Nd0.7Sr1.3CuO4-gamma at low temperature (200-300 degrees C) using CuF2 as fluorinating reagent. The oxyfluoride has K2NiF4 structure with S.G. I4/mmm as its precursors, but the evident lattice expansions were observed. The a-axis expands from 3.7257(2) Angstrom to 3.9288(5) Angstrom and c-axis from 12.8240(3) Angstrom to 12.9630(2) Angstrom. No trace of SrF2 was detected in these fluorinated products. XRD and magnetic measurement revealed that the superconductivity in the fluorinated products originated from the oxyfluorides with reduced CuO2 plane and in the presence of the apical anion.

关键词: hole concentration;copper;route;a=ca;tc

氢对Al-Li合金2091-T6组织性能的影响

林肇琦 , 赵刚 , 李洪晓 , 茹红强 , 刘春明

金属学报

本文研究了氢含量对Al－Li合金2091－T6薄板力学性能、应力腐蚀开裂寿命（SCCL）、变形机制和断口形貌的影响。结果表明，合金的氢含量由0.92μg／g降低到0.08μg／g时，力学性能和SCCL显著提高．变形机制由切割机制转变为绕过机制，拉伸和应力腐蚀试样的断裂模式由典型的沿晶脆性断裂转变为穿晶韧性断裂，氢脆引起的低韧性沿晶断裂特点完全消失.本文还讨论了脱氢对Al-Li合金变形机制和断裂模式影响的机理，提出了“超低氢Al-Li合金”的概念.

关键词: Al-Li合金2091－T6 , hydrogen embrittlement , mechanical property , stress-corrosion cracking life , deformation mechanism

快速凝固Al-Li-Cu-Mg-Zr合金中Z相和T相的结构关系

张立春 , 何安强 , 吴玉琨 , 叶恒强 , 张永昌

金属学报

利用高分辨电镜(HRTEM)和常规电子显微术研究了快速凝固Al-Li-Cu—Mg—Zr合金中Z相和T相的结构关系,发现两相间两种确定的晶体学取向关系,并以此为依据解释了Z相和T相的某些结构缺陷两相的结构有密切关联,其中一相中缺陷的扩展会导致另一相的形成

关键词: Al-Li-Cu-Mg-Zr合金 , Z hexagonal phase , T f.c.c. phase , shear structure

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