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1.
The structural, gaseous phase hydrogen storage, and electrochemical properties of a series of vanadium-free AB2 Laves phase based metal hydride alloys with various modifiers (Ti5Zr30Cr9Mn19Co5Ni32−xMx, M = B, Fe, Gd, Mg, and C) were studied. While B and Fe completely dissolve in the main AB2 phases, Gd, Mg, and C form individual secondary phases. The solubilities of Gd, Mg, and C in the AB2 phases are not detectable, 0.3 at.%, and very low, respectively. The C14 crystallite sizes, C15 phase abundances, and Zr7Ni10 phase abundances of modified alloys are larger than those of the base alloy. All modified alloys show decreases in plateau pressure, reversible gaseous phase storage capacity, formation activity, electrochemical capacity, and cycle life. A small amount of boron (0.2 at.%) and carbon in the alloy improve the half-cell high-rate dischargeability and bulk hydrogen diffusion. All modifiers, except for boron, reduce the surface exchange reaction current densities of the alloys. Both Mg and C show improvement in charge retention. Full-cell high-rate performance is improved by adding only a small amount of boron (0.2 at.%). Fe, Gd and 0.2 at.% of boron improve the low-temperature performance of the sealed batteries. 相似文献
2.
In an effort to reduce raw material cost and improve the charge retention characteristic of nickel metal hydride batteries, the Ti, Zr, and Ni-contents in vanadium-free AB2 metal hydride alloys were optimized according to their capacity, charge retention, activation, high-rate capability, low-temperature performance, and cycle stability. A multi-component hypo-stoichiometric AB2 alloy with a composition of Ti10Zr27Cr8Mn15Co5Ni35 was identified and compared to vanadium-containing AB2 metal hydride alloys. Vanadium-free alloys provided better charge retention performance but with a trade-off in cycle life. The gaseous and electrochemical storage properties were correlated to both the average composition and the stoichiometry of the main AB2 phases. 相似文献
3.
Yang-Huan Zhang Hui-Ping Ren Tai Yang Chen Zhao Li-Cui Chen Hong-Wei Shang Dong-Liang Zhao 《稀有金属(英文版)》2013,32(2):150-158
The La–Mg–Ni-based A2B7-type La0.8-x Nd x Mg0.2Ni3.35Al0.1Si0.05 (x = 0, 0.1, 0.2, 0.3, and 0.4) electrode alloys were prepared by casting and annealing. The influence of the partial substitution of Nd for La on the structure and electrochemical performances of the alloys was investigated. The structural analysis of X-ray diffraction and scanning electron microscopy reveals that the experimental alloys consist of two major phases: (La,Mg)2Ni7 with the hexagonal Ce2Ni7-type structure and LaNi5 with the hexagonal CaCu5-type structure as well as some residual phases of LaNi3 and NdNi5. The electrochemical measurements indicate that an evident change of the electrochemical performance of the alloys is associated with the substitution of Nd for La. The discharge capacity of the alloy first increases then decreases with the growing Nd content, whereas their cycle stability clearly grows all the time. Furthermore, the measurements of the high rate discharge ability, the limiting current density, and hydrogen diffusion coefficient all demonstrate that the electrochemical kinetic properties of the alloy electrodes first augment then decline with the rising amount of Nd substitution. 相似文献
4.
The effects of annealing treatment on the microstructure and electrochemical properties of low-Co LaNi3.55Mn0.35Co0.20Al0.20Cu0.75Fe0.10 hydrogen storage alloys were investigated. X-ray diffraction (XRD) analysis indicated that annealing treatment remarkably
reduced the lattice strain and defects, and increased the unit-cell volume. The optical microscope analysis showed that the
as-cast alloy had a crass dendrite microstructure with noticeable composition segregation, which gradually disappeared with
increasing annealing temperature, and the microstructure changed to an equiaxed structure after annealing the alloy at 1233
K. The electrochemical tests indicated that the annealed alloys demonstrated much better cycling stability compared with the
as-cast one. The capacity retention at the 100th cycle increased from 90.0% (as-cast) to 94.7% (1273 K). The annealing treatment
also improved the discharge capacity. However, the high rate dischargeability (HRD) value of the annealed alloy slightly dropped,
which was believed to be ascribed to the decreased exchange current density and the hydrogen diffusion coefficient in alloy
bulk. 相似文献
5.
K. Young T. OuchiB. Reichman J. KochM.A. Fetcenko 《Journal of Alloys and Compounds》2011,509(28):7611-7617
The structures and electrochemical properties of a series of annealed AB5, La10.5Ce4.3Pr0.5Nd1.4Ni64.3−xCo5.0Mn4.6Al6.0Cu3.2Zr0.2Fex (x = 0.0, 0.5, 1.0, and 1.5), metal hydride alloys were studied for improvement in the low-temperature performance of nickel/metal hydride batteries. As the Fe-content in the alloy increases, the following was observed: lattice constant a first increases and then decreases; lattice constant c and c/a ratio increase; unit cell volume increases monotonically; the main AB5 phase becomes hyper-stoichiometric containing no Zr and its Fe-content is close to the target composition; an additional AB7 phase appears; maximum gaseous hydrogen storage, PCT plateau pressure, and hysteresis first increase and then decrease while the trend of reversible hydrogen storage is the opposite; enthalpy and entropy of hydride formation remain unchanged; electrochemical full capacity decreases while the high-rate dischargeability and surface reaction exchange current increase; and bulk hydrogen diffusion increases first and then decreases by very small amounts. The product of charge-transfer resistance and double-layer capacitance measured at −40 °C indicates an improvement in the surface catalysis with Fe-addition. In the sealed cell, the addition of Fe improves both the specific power and −10 °C low temperature performance, slightly reduces the charge retention, and first marginally improves and then deteriorates the cycle life performance. 相似文献
6.
采用快淬方法制备添加Cu及Nd元素的具有纳米晶和非晶结构的(Mg24Ni10Cu2)100-x Nd x(x=0,5,10,15,20)合金。用X射线衍射(XRD)和高分辨率投射电镜(HRTEM)分析铸态及快淬态合金的相组成及结构,并研究Nd含量和快淬速率对合金相结构及吸氢性能的影响。结果表明,快淬态无Nd合金为纳米晶结构,而含Nd的快淬态合金则为纳米晶和非晶结构,表明添加Nd促进了合金的非晶形成能力。添加Nd及快淬处理均显著地促进了合金的气态及电化学动力学性能。添加Nd及快淬处理加快了氢原子在合金体内的扩散速率,但是均降低了合金电极表面的电荷传递性能,从而使得合金的高倍率放电性能(HRD)随着Nd含量和快淬速率的增加先上升而后下降。 相似文献
7.
Research of heat treatment of low-Co AB_5 type hydrogen storage alloys for MH-Ni batteries 总被引:5,自引:0,他引:5
GUO Jinghong CHEN Demin LIU Guozhong YANG Ke MA Jun) Institute of Metal Research Chinese Academy of Sciences Shenyang China) Suppo Battery 《稀有金属(英文版)》2003,22(3)
The effects of low-Co AB5 type hydrogen storage alloys prepared by quenching and annealing on the performances of MH-Ni batteries were investigated, and the characteristics of the low-Co AB5 type hydrogen storage alloys were compared with those of the high-Co AB5 type hydrogen storage alloy as well. The results showed that the faster the cooling of the low-Co hydrogen storage alloy is, the better homogeneity of the chemical composition for the alloy and the longer cycle life of the battery are, but the electrochemical discharge capacity and high-rate discharge ability are reduced. The high-rate discharge ability and charge retention of MH-Ni batteries for the conventional as-cast annealed low-Co hydrogen storage alloy were superior to those for the rapidly quenched low-Co hydrogen storage alloy and the high-Co hydrogen storage alloy, but a little inferior in the cycle life. 相似文献
8.
Yang-huan ZHANG Zhong-hui HOU Bao-wei LI Hui-ping REN Ying CAI Dong-liang ZHAO 《中国有色金属学会会刊》2013,23(5):1403-1412
The La-Mg–Ni–based A2B7-type La0.8-xNdxMg0.2Ni3.15Co0.2Al0.15 (x=0, 0.1, 0.2, 0.3, 0.4) electrode alloys were prepared by casting and annealing. The influences of partial substitution of Nd for La on the structure and electrochemical performance of the as-cast and annealed alloys were investigated. It was found that the experimental alloys consist of two major phases, (La, Mg)2Ni7 phase with the hexagonal Ce2Ni7-type structure and LaNi5 phase with the hexagonal CaCu5-type structure, as well as some residual phase LaNi3 and NdNi5. The discharge capacity and high rate discharge ability (HRD) of the as-cast and annealed alloys first increase and then decrease with Nd content growing. The as-cast and annealed alloys (x=0.3) yield the largest discharge capacities of 380.3 and 384.3 mA·h/g, respectively. The electrochemical cycle stability of the as-cast and annealed alloys markedly grows with Nd content rising. As the Nd content increase from 0 to 0.4. The capacity retaining rate (S100) at the 100th charging and discharging cycle increases from 64.98% to 85.17% for the as-cast alloy, and from 76.60% to 96.84% for the as-annealed alloy. 相似文献
9.
Masoud MOHAMMADI RAHVARD Morteza TAMIZIFAR Seyed Mohammad Ali BOUTORABI 《中国有色金属学会会刊》2018,28(8):1543-1552
The formation of bulk metallic glasses (BMGs) in the ternary Zr56Co28Al16 and quaternary Zr56Co28–xCuxAl16 (x=2, 4, 5, 6, 7, mole fraction, %) glassy alloys was investigated via the copper mold suction casting method. The main purpose of this work was to locate the optimal BMG-forming composition for the quaternary ZrCo(Cu)Al alloys and to improve the plasticity of the parent alloy. The X-ray diffractometry (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) were used to investigate the glassy alloys structure and their glass forming ability (GFA). In addition, the compression test, microhardness, nano-indentation and scanning electron microscopy (SEM) were utilized to discuss the possible mechanisms involved in the enhanced plasticity achievement. The highest GFA among Cu-containing alloys was found for the Zr56Co22Cu6Al16 alloy, which was similar to that of the base alloy. Furthermore, the plasticity of the base alloy increased significantly from 3.3% to 6% for the Zr56Co22Cu6Al16 BMG. The variations in the plasticity and GFA of the alloys were discussed by considering the positive heat of mixing within Cu and Co elements. 相似文献
10.
Hydrogen storage characteristics of nanocrystalline and amorphous Mg2Ni-type alloys prepared by melt spinning 总被引:1,自引:0,他引:1
Yang-huan Zhang Feng Hu Zhi-gang Li Ke Lü Shi-hai GuoXin-lin Wang 《Journal of Alloys and Compounds》2011,509(2):294-300
In order to improve the hydrogen storage characteristics of the Mg2Ni-type alloys, Ni in the alloy is partially substituted by element Mn, and melt-spinning technology is used for the preparation of the Mg2Ni1−xMnx (x = 0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys. The microstructures of the as-cast and spun alloys are characterized by XRD, SEM and HRTEM. The hydrogen absorption and desorption kinetics of the alloys are measured by an automatically controlled Sieverts apparatus. The electrochemical performances are tested by an automatic galvanostatic system. The results show that the as-spun Mn-free alloy holds typical nanocrystalline structure, whereas the as-spun alloys containing Mn displays a nanocrystalline and amorphous structure. The hydrogen absorption and desorption capacities and kinetics of the alloys increase with rising spinning rate. Additionally, melt spinning markedly improves the electrochemical hydrogen storage capacity and cycle stability of the alloys containing Mn. With an increase in the spinning rate from 0 (As-casts is defined as spinning rate of 0 m/s) to 30 m/s, the discharge capacity of the (x = 0.3) alloy mounts up from 92.3 to 211.1 mAh/g, and its capacity retaining rate at 20th charging and discharging cycle grows from 36.21% to 76.02%. 相似文献
11.
《中国铸造》2012,(1):43-47
To improve the strength,hardness and heat resistance of Mg-Zn based alloys,the effects of Cu addition on the as-cast microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb high zinc magnesium alloy were investigated by means of Brinell hardness measurement,scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS),XRD and tensile tests at room and elevated temperatures.The results show that the microstructure of as-cast Mg-10Zn-5Al-0.1Sb alloy is composed of α-Mg,t-Mg32(Al,Zn)49,φ-Al2Mg5Zn2 and Mg3Sb2 phases.The morphologies of these phases in the Cu-containing alloys change from semi-continuous long strip to black herringbone as well as particle-like shapes with increasing Cu content.When the addition of Cu is over 1.0wt.%,the formation of a new thermally-stable Mg2Cu phase can be observed.The Brinell hardness,room temperature and elevated temperature strengths firstly increase and then decrease as the Cu content increases.Among the Cu-containing alloys,the alloy with the addition of 2.0wt.% Cu exhibits the optimum mechanical properties.Its hardness and strengths at room and elevated temperatures are 79.35 HB,190MPa and 160MPa,which are increased by 9.65%,21.1% and 14.3%,respectively compared with those of the Cu-free one.After T6 heat treatment,the strengths at room and elevated temperatures are improved by 20% and 10%,respectively compared with those of the as-cast alloy.This research results provide a new way for strengthening of magnesium alloys at room and elevated temperatures,and a method of producing thermally-stable Mg-10Zn-5Al based high zinc magnesium alloys. 相似文献
12.
Pressure–composition–temperature hysteresis in C14 Laves phase alloys: Part 1. Simple ternary alloys
In Part 1 of a series of two papers, the a/c lattice constant ratio of ZrCr2-based ternary alloys are shown to be strongly correlated not only to the number of outside electrons of substitutional elements but also to the PCT absorption/desorption hysteresis and the degree of pulverization during hydride/dehydride cycling of the alloy. In differentiation from AB5 alloys in which elongating the c-axis dimension of the unit cell extends the alloy's electrochemical cycle life, flattening the unit cell of an AB2 alloy extends its cycle life. This difference can be explained by the different hydrogen occlusion sites of the two structures. Adding small amounts (10%) of substituents such as Zn, Cr, Mo, Si, or Cu, was generally found to help the prevention of the alloy hydride/dehydride pulverization by maintaining a relatively high a/c lattice constant ratio. Application of these principles to more complicated electrochemical hydrogen storage alloys can be found in Part 2 of this series. 相似文献
13.
锌合金粉在KOH溶液中析氢行为的研究 总被引:1,自引:0,他引:1
采用气雾法制备Zn-In,Zn-Pb,Zn-Bi,Zn-Al合金粉,利用收集气体的办法测定了各种合金粉在KOH溶液中的腐蚀速度,确定了In,Pb,Bi,Al四种元素与Zn分别形成合金的最佳含量,随后研究了In,Bi,Al三种金属元素与Zn形成的四元合金的析氢行为。 相似文献
14.
为改善Mg2Ni储氢合金电化学性能,采用机械合金化法(Mechanical Alloying,MA),分别制备出改性合金Mg1.8 Zr Ni以及MgTi3,按一定比例和Ni混合球磨,制备出纳米晶或非晶化的Mg1.8Zr0.2Ni- (1.2-x)Ni -xMgTi3复合储氢合金。研究结果表明,经部分取代改性和包覆修饰后的复合储氢合金,其表面和内部形成较多的纳米级褶皱、空隙层状和多相结构缺陷。随着MgTi3含量增加,Mg1.8Zr0.2Ni- (1.2-x)Ni -xMgTi3复合储氢合金初始放电比容量也逐渐增加,当MgTi3含量为x=0.5时,合金初始放电比容量为973.3 mAh.g-1。但MgTi3含量超过x=0.5时,其初始放电比容量又有所下降,研究表明添加MgTi3却不利于复合储氢合金的循环稳定性和高倍率放电性能。通过对Mg1.8Zr0.2Ni- (1.0-x)Ni -xMgTi3复合储氢合金进行线性极化、阳极极化和交流阻抗测试,进一步研究了系列合金电极的表面电化学反应、电荷转移过程、氢在合金中的扩散情况以及它们的电化学性能。 相似文献
15.
Yang-Huan Zhang Bao-Wei Li Hui-Ping Ren Zhong-Wang Wu Xiao-Ping Dong Xin-Lin Wang 《Journal of Alloys and Compounds》2008,460(1-2):414-420
In order to improve the cycle stability of the La–Mg–Ni system PuNi3-type hydrogen storage electrode alloys, Ni in the alloy was partially substituted by Fe. The La0.7Mg0.3Co0.45Ni2.55−xFex (x = 0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by casting and rapid quenching. The effects of the substitution of Fe for Ni on the structures and electrochemical performances of the as-cast and quenched alloys were investigated in detail. The results of the electrochemical measurement indicate that the substitution of Fe for Ni obviously decreases the discharge capacity, high rate discharge capability (HRD) and discharge potential of the as-cast and quenched alloys, but it significantly improves their cycle stabilities, and its positive impact on the cycle life of as-quenched alloy is much more significant than on that of the as-cast one. The microstructure of the alloys analyzed by XRD, SEM and TEM show that the as-cast and quenched alloys have a multiphase structure which is composed of two major phases (La, Mg)Ni3 and LaNi5 as well as a residual phase LaNi2. The substitution of Fe for Ni helps the formation of a like amorphous structure in the as-quenched alloy. With the increase of Fe content, the grain sizes of the as-quenched alloys significantly reduce, and the lattice constants and cell volumes of the alloys obviously increase. 相似文献
16.
《Acta Materialia》2003,51(3):741-752
In this study the occurrence of temperature induced porosity (TIP) in hot isostatically pressed (HIP) compacts of different gamma Titanium aluminide alloys was investigated. Two gamma Titanium aluminide alloys Ti-48.9at.%Al and an advanced Niobium containing alloy Ti-46at.%Al-9at.%Nb have been atomized by gas atomization and by centrifugal atomization in an inert gas atmosphere. The alloy powders were studied regarding porosity and the content of inert gas entrapped in the powder particles. Selected powder batches were hot isostatically pressed at 1280 °C and were investigated with respect to TIP evolution after a high temperature exposure to 1390 °C for short and long time periods. It was found that gas atomized Titanium aluminide alloy powders contain a certain amount of atomization gas, the concentration of which increases with the powder particle size. The amount of inert gas entrapped in centrifugally atomized powders is higher as compared to powders produced by gas atomization. The occurrence of TIP after high temperature annealing of the HIP’ ed compacts depends on the grain size, the processing medium (Argon or Helium), the amount of entrapped inert gas and the annealing time. Guidelines are presented for minimizing or prevention of TIP in γ-TiAl alloys processed by powder metallurgy. 相似文献
17.
Rapidly solidified Al-Si-Fe base alloys were prepared by gas atomization, hot pressing and extrusion. To optimize wear resistance
and mechanical properties, Al-20 wt.%Si-5 wt.%Fe base alloys containing 1–3 wt.%Ti were newly designed and characterized in
detail. The additions of Ti (especially, ~2 wt.%Ti) effectively increased the wear resistance and mechanical properties such
as tensile strength and hardness; however, the addition of 3 wt.%Ti was not desirable because of the precipitation of the
primary Ti7Al5Si12 phase in the as-quenched state. Based on TEM analyses, the improved properties in the Al-Si-Fe alloys containing Ti were
found to be due to the formation of the (Al, Si)3Ti phase finely dispersed in the matrix.
ASCM16CE is the gas atomized and consolidated composite including 3 wt.% of SiC particles (reference alloy). 相似文献
18.
1 Introduction Mischmetal-based AB5-type alloys containing about 10% Co (mass fraction) are now widely used as the negative electrode materials of Ni/MH batteries because of their long cycle life and good overall properties. It is known that Co is an ess… 相似文献
19.
Ho-Sung Kim Jeon Min Kim Tae-Won Kim Ik-Hyun Oh Jeon Choi Choong Nyeon Park 《Metals and Materials International》2008,14(4):497-503
Hydrogen storage alloys based on LmNi4.2Co0.2Mn0.3Al0.3 were fabricated to study the equilibrium hydrogen pressure and electrochemical performance. The surface morphology and structure
of the alloys were analyzed by SEM and XRD, and then the hydrogenation behaviors of all alloys were evaluated by PCT and electrochemical
half-cell. We studied the hydrogenation behavior of the Lm-based alloy with changes in composition elements such as Mn, Al,
and Co and investigated the optimal design for Lm-based alloy in a sealed battery system. As a result of studying the hydrogenation
characterization of alloys with the substitution elements, hydrogen storage alloys such as LmNi3.75Co0.15Mn0.5Al0.3 and LmNi3.5Co0.5Mn0.5Al0.5 were obtained to correspond with the characteristics of a sealed battery with a higher capacity, long life cycle, lower internal
pressure, and lower battery cost. The capacity preservation rate of LmNi3.5Co0.5Mn0.5Al0.5 was greatly improved to 92.7% (255 mAh/g) at 60 cycles, indicating a low equilibrium hydrogen pressure of 0.03 atm in PCT
devices. 相似文献
20.
《中国有色金属学会会刊》2020,30(7):1816-1825
The effect of rolling reduction and annealing process on the microstructure and corrosion behavior of Mg−9Li−1Zn (LZ91) alloy was investigated. The test alloy sheets were cold rolled with the reduction of 50% and 75%, respectively, and then were annealed at 200 °C for 1 h. The microstructure of test alloys was observed by OM and SEM while the phase composition was determined by XRD. The corrosion property was evaluated by electrochemical measurements and immersion tests. The results show that LZ91 alloy sheet consists of α-Mg, β-Li and precipitated Mg−Li−Zn compounds (MgLi2Zn and MgLiZn phases). Dynamic recrystallization grains appear in β-Li phase during annealing process, leading to grain refinement. The results indicate that the increasing rolling reduction and performing the annealing process can enhance the corrosion resistance of LZ91 alloy. The 75% cold-rolled and annealed LZ91 alloy shows the best corrosion resistance. 相似文献