材料期刊网

CELLULAR SPACING SELECTION OF Al-0.53wt%Zn ALLOY UNDER NEAR-RAPID DIRECTIONAL SOLIDIFICATION CONDITION

J. Feng , W.D. Huang , X. Lin , T. Li , Y.F. Xue and Y.H. Zhou(State Key Lab. of Solidilication Processing , Northwestern Polytechnical University , Xi'an 710072 , China)

金属学报(英文版)

In order to investigate the response of cellular spacing to the variation of growth velocity under near-rapid directional solidification condition, Al-0.53wt%Zn alloy is directionally solidified with Bridgman apparatus. The results show that at the given temperature gradient the obtained microstrvctures are all cells and there exists a wide distribution range of cellular spacing. The maximum, λmax, minimum, λmin, and average cellular spacing, λ, as functions of growth rate, V, can be given by λmax=948.51V-0.4961, λmin= 661.16V-0.5015 and λ=412.41V-0.5049, respectively. The experimental results are compared with that predicted by KGT model, and a good agreement is found. Moreover,it is found that the average cellular spacing is also remarkably history-dependent.

关键词: Al-Zn alloy , null , null , null

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

CONGRATULATIONS TO PROF. T. KO'S 90th BIRTHDAY Editorial Board of ACTA METALLURGICA SINICA

金属学报(英文版)

关键词:

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

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

2099-T83/2060-T8异质Al-Li合金搅拌摩擦焊搭接界面结构与力学性能

刘奋军 , 傅莉 , 张纹源 , 孟强 , 董春林 , 栾国红

金属学报 doi:10.11900/0412.1961.2014.00297

采用搅拌摩擦焊(FSW)对厚度为2mm的2099-T83与2060-T8 Al-Li合金进行搭接.利用OM和SEM等分析技术探讨搅拌头转速和搅拌针长度对搭接接头界面结构与力学性能的影响.结果表明,2099-T83/2060-T8搭接接头焊缝区可观察到明显的结合界面,焊缝区显微硬度低于母材,且在热机影响区与焊核区的过渡区硬度最低.当搅拌头转速由600 r/min增加到800 r/min,且搅拌针长度由3.0mm减小至2.5mm时,界面形貌由光滑界面转变成“锯齿状”咬合界面,焊缝区结合界面形貌主要受搅拌针长度影响,“锯齿状”咬合界面搭接接头平均破坏载荷为654N.搭接接头均在底部母材2060-T8侧热机影响区与焊核区的过渡区断裂,断裂特征为韧-脆混合断裂.“锯齿状”咬合界面搭接接头经150℃,保温20 h人工时效处理后,焊缝区显微硬度有所提升,接头承载能力较未经人工时效处理的降低了20％,断口呈现脆性断裂模式.

关键词: 2099-T83 Al-Li合金 , 2060-T8 Al-Li合金 , 搅拌摩擦焊接 , 人工时效处理 , 界面形貌 , 接头强度

2197(Al-Li)-T851合金的疲劳裂纹萌生与扩展行为研究

陈圆圆 , 郑子樵 , 蔡彪 , 徐建秋 , 佘玲娟 , 李海

稀有金属材料与工程

研究了2197-T851合金的疲劳裂纹萌生与扩展特性.结果表明,2197铝锂合金的疲劳裂纹萌生与应力水平有关,在较低应力下,主要萌生在第二相粒子、第二相粒子/基体界面以及表面缺陷处,而在较高应力水平下,还出现沿滑移带和晶界处萌生.裂纹的扩展优先沿有利滑移面,在晶粒间的扩展以沿{111}面的穿晶扩展为主,也有沿小角度晶界扩展的情况,合金具有很好的平面滑移性.裂纹在晶粒内的扩展并非沿一个滑移系的直线扩展而是频繁发生偏折,却始终沿{111}面,可剪切共格相δ'粒子造成晶内扩展路径曲折.

关键词: 2197铝锂合金 , 裂纹萌生和扩展 , EBSD , 疲劳断口

Effects of high magnetic fields on the microstructures and grain boundaries in binary Al-Li alloy

Journal of Alloys and Compounds

The effects of high magnetic fields on the as-cast microstructure and grain boundaries of binary Al-Li alloy were investigated. It was found that secondary dendrite arm spacing (SDAS) decreased and the distribution of the SDAS became uniform under high magnetic fields. The application of a high magnetic field had no effect on the type of precipitated phases in the alloy, although delta' (Al(3)Li) precipitates coarsened under the field of 11.5 T. Area fraction of grain boundary (AFGB) slightly decreased at first and then increased with increasing magnetic flux density under uniform magnetic fields, while it decreased under magnetic field gradients. (C) 2008 Elsevier B.V. All rights reserved.

关键词: Metals and alloys;Precipitation;Grain boundaries;Microstructure;High;magnetic fields;aluminum-lithium alloys;austenitic decomposition;intergranular;fracture;eutectic alloy;steel;solidification;transformation;composites;behaviors;toughness

Effect of carbon addition on hydrogen storage behaviors of Li-Mg-B-H system

International Journal of Hydrogen Energy

Various carbon additives were mechanically milled with LiBH(4)/MgH(2) composite and their hydrogen storage behaviors were investigated. It was found that most of the carbon additives exhibited prominent effect on the host material. Among the various carbon additives, purified single-walled carbon nanotubes (SWNTs) exhibited the most prominent effect on the kinetic improvement and cyclic stability of Li-Mg-B-H system. Results show that LiBH(4)/MgH(2) composite milled with 10 wt.% purified SWNTs additive can release nearly 10 wt.% hydrogen within 20 mm at 450 degrees C, which is about two times faster than that of the neat LiBH(4)/MgH(2) sample. On the basis of hydrogen storage behavior and structure/phase investigations, the possible mechanism involved in the property improvement upon carbon additives was discussed. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

关键词: Hydrogen storage;Lithium borohydride;MgH(2);Carbon;Mechanical;milling;arc-discharge method;libh4;nanotubes;composites;hydride