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ON SPINODAL BOUNDARIES OF Al-Li ALLOYS

WEI Yinghui , WANG Xiaotian (School of Materials Scince and Engineering , Xi'an Jiaotong University , Xi'an 710049 , China Manuscript received 10 Mareh , 1994)

金属学报(英文版)

The spinodal decomposition can occur in Al-Li alloys containing 5.8-14.2 at.% Li at room temperature. The modutated structure wavelength is approximately 3.1 nm for com mercial Al-LI alloys. The limit composition of the miscibility gap is 3.66 -16.06 at.%Li at 298 K. The highest temperature of the miscibility gap is 377 K.

关键词: : Al-Li alloy , null , null

CRYSTAL STRUCTURE OF γ-Li_xFe_2O_3 WITH ELECTROCHEMICAL INSERTION OF Li

HUANG Jianshun CHEN Junming Shanghai Institute of Metallurgy , Academia Sinica , Shanghai , China Research Associate , Shanghai Institute of Metallurgy , Academia Sinica , Shanghai 200050 , China

金属学报(英文版)

Crystal structure of γ-Li_xFe_2O_3,inserted Li electrochemically,was studied by Moss- bauer spectroscopy together with X-ray diffraction,XPS and electrochemical method,On the insertion of Li at low current density,the crystal structure is keeping original spinel; while at higher current density or by thermal activation,owing to violent movement of Li~+ ions,part of crystal structure transforms into rock type similar to face-centered cubic structure of ferrous oxide.The transition channels during insertion of Li~+ ions and limitation of Li~+ ions inserted were discussed.

关键词: null , null , null

Al—Li合金的晶界断裂

姚大平 , 张匀 , 胡壮麒 , 李依依

材料研究学报

本文研究了两种晶粒组织的二元Al-Li 合金拉伸性能与断裂行为。结果表明Al-Li 合金力学性能与晶粒尺寸有关,其断裂行为决定于PFZ 内平面滑移或晶界沉淀相与滑移的交互作用。

关键词: Al—Li合金 , intergranular fracture , planar slip

Effect of Li(3)N additive on the hydrogen storage properties of Li-Mg-N-H system

Journal of Materials Research

The effect of Li(3)N additive on the Li-Mg-N-H system was examined with respect to the reversible dehydrogenation performance. Screening Study with varying Li(3)N additions (5, 10, 20, and 30 mol%) demonstrates that all are effective for improving the hydrogen desorption capacity. Optimally, incorporation of 10 mol% Li(3)N improves the practical capacity from 3.9 wt% to approximately 4.7 wt% hydrogen at 200 degrees C, which drives the dehydrogenation reaction toward completion. Moreover, the capacity enhancement persists well over 10 de-/rehydrogenation cycles. Systematic x-ray diffraction examinations indicate that Li(3)N additive transforms into LiNH(2) and LiH phases and remains during hydrogen cycling. Combined structure/property investigations suggest that the LiNH(2) "seeding" should be responsible for the capacity enhancement, which reduces the kinetic barrier associated with the nucleation of intermediate LiNH(2). In addition, the concurrent incorporation of LiH is effective for mitigating the ammonia release.

关键词: complex hydrides;improvement;mixtures;imides;amide;h-2

SUPERPLASTICITY OF A RAPIDLY SOLIDIFIED AI-Li ALLOY

MANG Weishi WANG Guozhi ZHANG Yongchang HU Zhuangqi SHI Changxu Institute of Metal Research , Academia Sinica , Shenyang , China Yongchang Associate Professor , Institute of Metal Research , Academia Sinica , Shenyang 110015 , China

金属学报(英文版)

A rapidly solidified microcrystalline Al-Li-Cu-Mg-Zr alloy and its superplasicity have been investigated.An optimum tensile elongation of 585% was obtained at 540℃ and strain rate 1.67×10~(-2)s~(-1).The superplastic Al-Li alloy is manufaetured using thermomechanical pro- cessing:solution,overaging,warm rolling and recrystallization.Microstructural changes in thermomechanical processing and cavitation occurred during superplastic deformation have been observed.The superplastic failure of alloy may be caused mainly by nucleation and growth of cavities as well as the linkage around grains.

关键词: superplasticity , null , null , null

Al-Li合金强韧化机理及途径

甘卫平 , 周兆锋 , 杨伏良

材料导报

概述了Al-Li合金强韧化的内部机理和外部机理,并在此基础上阐述了提高Al-Li合金强韧性的主要途径.

关键词: Al-Li合金 , 强韧性 , 途径

Preparation of Li-B alloy and study of its microstructure and discharge characteristics

Zhijian LIU , Zhiyou LI , Wei DUAN , Xuanhui QU , Baiyun HUANG , Siqi ZHANG

材料科学技术(英)

A LI-B alloy has been prepared using a pretreated amorphous B powder and pure Li ingot as starting materials by continually slow addition of B powder and intensified stirring in the process of melting. The microstructure and the discharge characteristic of the materials have been investigated. Results show that the problem of temperature control in synthesis would be modified by means of continual addition of B powder, the Li7B6 would be more finery distributed in the metal Li by means of intensified stirring. The discharge characteristic of the Li-B alloy using amorphous B as starting materials is almost the same with that of using crystalline B.

关键词:

Al-Li合金时效初期的价键分析

高英俊 , 黄创高 , 莫其逢 , 蓝志强 , 刘慧 , 韦银燕

中国有色金属学报

运用固体经验电子理论(EET),对Al-Li合金时效初期的若干偏聚晶胞的价电子结构进行了计算.计算结果表明:不包含空位的偏聚晶胞的键络最强键为Al-Al键,其中Al原子的共价半径较Li原子的共价半径要大;而含空位的偏聚晶胞的最强键为Al-Li键,Al原子的共价半径要比Li原子的共价半径要小;在空位存在的情况下,由于Al原子与Li原子的电负性相差明显,促使Al和Li原子结合,倾向形成Al-Li短程序结构偏聚区,这种含空位的短程序结构很可能就是δ′(Al3Li)亚稳相的前兆结构和生长胚胎;由于Al-Li-空位有序偏聚晶胞的Al-Li键络比基体键络要强许多,因此,淬火过程中合金生成的Al-Li-空位偏聚晶胞对合金过饱和固溶体起主要强化作用;后续析出的δ′(Al3Li)亚稳相键络各项异性显著,键络强度明显提高;由于Al3Li与基体共格,其大量均匀弥散析出起到提升基体整体键络强度,同样对合金产生强化作用.

关键词: Al-Li合金 , Al3Li , 空位 , 价电子结构 , 力学性能

THE SOLIDIFICATION BEHAVIOR OF 8090 AL-LI ALLOY

Metallurgical Transactions B-Process Metallurgy

In this work, the solidification and segregation behaviors of 8090 Al-Li alloy have been investigated with differential thermal analysis (DTA) and the metallographic-electron microprobe method. The results show that 8090 Al-Li alloy has a much more complex solidification path than Al-Li binary alloy due to the addition of many alloying elements and the presence of impure elements. Solidification begins at about 635-degrees-C with the reaction of L --> alpha-Al + L', and this reaction goes on to termination. The alloying element Cu and impure elements Fe and Si have a strong segregation tendency. During solidification, Cu segregates to the interdendrite and finally forms alpha-Al + T2 eutectic. As a result, the solidification temperature range is greatly extended. Iron and Si form the insoluble constituents Al7Cu2Fe, AlLiSi, etc., although their concentrations in the alloy are quite low. With the increase of Fe content, there is a eutectic reaction of alpha-Al/Al3Fe at about 595-degrees-C. The formation of insoluble constituents is influenced by both concentrations of impure elements in the alloy and the cooling rate.

关键词: fracture-behavior;phase-equilibria;cu alloys;microstructure;lithium;zr

Structure in binary liquid Li-Mg alloys

材料科学技术(英)

Molecular dynamics simulations combining potentials mapping technique have been performed to investigate the structure of: binary liquid Li-Mg alloys at a constant temperature (924 K). Pair correlation function, bond orientational order and pair analysis approach are adopted to give geometrical descriptions on atom arrangement. The trends of splitting of second-peak in pair correlation function, the orientational order parameters and evolution of various symmetries of bonded pairs, etc., vs composition have been examined. The difference and concordance between the bond-orientational order and pair analysis have been first given out. Based on the distribution of attractive part of potentials, it is concluded that the attractive part would dominate the characterization of structure in liquid metals. In addition, icosahedra, defective icosahedra, Frank-Kasper polyhedra and Bernal hole polyhedra formed in liquid Li-Mg alloys are also counted.

关键词: variational thermodynamic calculations;sd metals;order

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