放电等离子烧结制备Mg2-xNdxNi(x=0~0.3)储氢合金

采用放电等离子烧结(SPS)工艺制备了Mg_2-xNd_xNi(x=0,0.1,0.2,0.3)储氢合金.通过X射线衍射(XRD)和扫描电镜(SEM)研究了合金的相结构和表面形貌,利用等容压差法分析测试了合金的压力-组成-温度(PCT)曲线和吸放氢动力学性能,研究了烧结温度、稀土元素Nd对储氢合金微观组织结构和储氢性能的影响,比较了SPS技术与真空感应熔炼法制备的Mg基合金组织结构和储氢性能的异同.结果表明:SPS制备的Mg_2-xNd_xNi(x=0~0.3)系列储氢合金具有多相结构,储氢合金的吸放氢动力学性能良好;Nd元素有利于Mg合金化,不利于储氢量;烧结温度对储氢量、PCT曲线平台性能有明显影响;当Mg_2-xNd_xNi系合金中含有Mg和NdMg₁₂相,PCT曲线出现双平台现象;与铸态合金相比,SPS制备的Mg_1.7Nd_0.3Ni储氢合金的吸放氢动力学性能较好,但储氢容量、放氢率和PCT曲线平台性能更差.     

Strip Casting of High Performance Structural Alloys

There exists a great need for the development of high performance alloys due to increasing demands for energy conservation and environmental protection. Application of strip casting shows a strong potential for the improvement of properties of existing alloys and also for the development of novel alloy systems with superior properties. The present paper reviews our Center's activities in the development of high performance alloys by strip casting. Examples include (1) Al alloys, (2) wrought Mg alloys, and (3) bulk metallic glass (BMG) alloys.     

Microstructures and Electrochemical Properties of Cobalt-Free LaNi4.0Al0.2Fe0.4Cu0.4-x Snx (x = 0 ～ 0.4) Electrode Alloys Prepared by Casting

The microstructure, hydriding performance, and electrochemical properties of LaNi4.0Al0.2Fe0.4Cu0.4- x Snx(x = 0 ～ 0.4) hydrogen storage alloys prepared by casting were investigated using XRD, SEM, pressure-composition isotherms, and electrochemical measurements. Substitution of Sn for Cu leads to the precipitation of LaNiSn phase. With increasing amount of tin substitution, cell volume, plateau pressures, and discharge capacities of the alloys decrease,whereas the cycle life of the alloys improves.     

Effects of Cobalt Content and Preparation on Electrochemical Capacity of AB5-Type Hydrogen Storage Alloys at Different Temperature

The effects of Co as a substituent for Ni on microstructure and electrochemical capacity of hydrogen storage alloys MI(NiCoMnAl)5.4 at -30～ 80 ℃, in which the content of Co was 0, 1.31%, 2.63%, 3.94%, 5.25%, and 6.56% (mass fraction), respectively, were reported. All of the alloys were prepared by vacuum induction melting followed by melt-spinning. It is found that the electrochemical capacity of alloys at different temperature depends upon the compositions and preparation methods. The electrochemical capacity of alloys increases at higher temperature (40 ～ 80 ℃ )and decreases at lower temperature ( - 30 ～ 0 ℃ ) with an increasing cobalt content. With an increasing temperature,melt-spinning is more favorable for improved capacity of the alloys than casting. Analyses of the charging/discharging potential curves illustrate that higher cobalt content and melt-spinning techniques are more effective to increase the capacity at higher temperature because of the higher hydrogen evolution potential. On the contrary, the capacity of alloys at lower temperature can be increased by decreasing cobalt content and casting, which is ascribed to higher hydrogen evolution potential and delayed hydrogen evolution reaction, as well as reduced potential drop in the charging/discharging process.XRD patterns confirm that all of the specimens present a single hexagonal CaCu5-type structure and an increased lattice parameters with increasing Co content. The FWHM of the main peak of melt-spun ribbons reduces because of more homogeneous composition and less lattice strain defects.     

稀土基AB5型复合贮氢合金的研究进展

制备复合合金是改善贮氢合金性能的一条有效途径。本文对国内外各种多元以及多相稀土复合贮氢材料的研究现状进行了综合评述，主要涉及了AB5-AB2型复合贮氢合金和镁基-AB5型纳米复合贮氢合金的进展。阐述了各种复合材料的组成，微观结构以及电化学性能等，并展望了今后复合贮氢材料的研究方向为应用基础性的研究，如复合作用机制、对热力学性能的影响等方面的研究。     

Nd-Fe-B永磁制粉技术及特点

对几种重要的Nd-Fe-B稀土永磁粉末的制备技术如盘磨臁磨、机械合金化、熔体快淬、超声气体雾化、带铸以及HDDR（Hydrogenation-Disproportionation—Desorption—Recombination）技术进行了评论。指出制粉技术从物理破碎、快速凝固技术到氢化反应的发展，改变了合金成分及工艺设计，实现了微观结构和磁体性能的改善，促进了Nd-Fe-B稀土永磁材料的应用。     

含Fe低CoAB5型贮氢合金的性能与结构

得到综合电性能良好的低CoAB5型贮氢合金成分。本文对所设计的一系列含Fe低CoAB5型贮氢合金MmNi3．55Co0.75-xMn0.4Al0.3Fex（x=0，0.1，0.2，0.3，0.4，0.5）进行了相关性能与结构测试，同时分析了对低CoMmB5合金结构参数与电性能之间的关系进行详细分析与表征。     

军用铸造铝合金标准物质的研制

介绍了军用铸造铝合金标准物质研制全过程 ,以及该标准物质定值的准确可靠性。     

急冷对Ti_(0.32)Cr_(0.345)V_(0.25)Fe_(0.03)Mn_(0.055)合金储氢性能的影响

为了研究急冷对储氢合金残余氢量的影响,利用真空电弧熔炼炉和铜模喷铸制备了Ti_(0.32)Cr_(0.345)V_(0.25)Fe_(0.03)Mn_(0.055)合金,采用XRD、PCT(压力-容量-温度)、TG/DTA等手段分析了急冷对储氢合金吸放氢性能的影响。结果表明,铸态合金和急冷合金均由BCC固溶体主相和Laves第二相组成;急冷对首次吸氢动力学行为影响较大,由铸态时的化学反应控制变为急冷时的新相晶核形成长大控制;急冷后,合金吸放氢平台压得到提高,且吸氢起始点左移,但吸放氢滞后性增大。TG/DTA曲线表明,急冷并没有改变合金的残余氢量,但氢化物放氢温度升高。     

AB5型贮氢合金结构分析

贮氢合金的电极性能取决于贮氢合金的微结构。从晶体结构、电子结构及化学键结构等各方面对市场上广泛应用的AB5型贮氢合金的结构进行综述，同时讨论合金结构与合金吸放氢性能之间的关系。     

热喷涂制备非晶合金涂层性能的研究进展

首先介绍了非晶合金的理论基础,然后从耐磨性和耐蚀性两个方面入手,详细地阐述了国内外对于热喷涂非晶合金涂层性能研究进展情况,并系统地总结了非金合金涂层在耐磨性和耐蚀性上的本质联系和根本矛盾,最后指出热喷涂非晶合金涂层性能研究上的局限性,提出三点问题:对于非晶合金基础理论的研究还处在起步阶段、热喷涂制备非晶合金涂层的合金体系种类少、制备非晶合金涂层的热喷涂技术有待开发,并针对以上三点问题提出热喷涂制备非晶合金涂层性能研究的未来发展方向。      

硼的添加对Mg2Ni储氢合金吸放氢性能的影响

镁系储氢合金有着价格低廉、储氢量大等优点,作为机载储氢材料有着广泛的应用前景,但其过高的氢分解温度,过慢的分解速度等缺点制约着实际应用.采用机械球磨制备出Mg2 Ni-xB(x =0％,1％,5％,10％,15％)系列储氢合金.通过XRD分析了合金的物相结构,采用P-C-T测试仪测定了合金的吸放氢性能,研究了添加不同含量的B对Mg2Ni合金吸放氢性能的影响.研究结果表明,B的添加对合金在200和300℃下吸放氢性能的改善作用不明显,但添加B的合金在400℃下的吸氢量均较Mg2Ni高,B的添加量由1％增至15％的合金吸氢量分别为3.09％,3.00％,2.81％,2.84％,而Mg2Ni的吸氢量则只有2.60％.随着B含量的增加,含B合金吸氢量略有降低;在含B的试样中,含5％B的合金吸氢速率最大,仅需180 s便能完成吸氢.所有含B合金的放氢平台均较Mg2Ni高且较为平坦.本次实验表明,B的添加量对合金性能的提升存在一个最优值,本次实验结果显示,添加5％B相对较好地改善合金的储氢性能,提高合金吸氢量和放氢平台压的同时能保持较快的吸氢速率.     

机械合金化纳米晶材料研究进展

综述了机械合金化制备纳米晶材料的研究进展，重点介绍了高强度铝合金，铜合金，难熔金属化合物，金属储氢材料，复相烯土永磁材料等几类机械合金化纳米晶材料的制备与组织性能，指出了机械合金化技术在纳米晶材料制备方面的优势及应用前景。     

Modelling and simulation of twin-roll casting of bulk metallic glasses

As an economic and direct route to continuous thin strip production from the melt, twin roll casting (TRC) has been established as an effective process for aluminium alloys. Its adaptation to casting of bulk amorphous alloy strip necessitates matching of the thermal and mechanical behaviour of the cooling multi-component melt to the requirements (especially cooling rate, and strip exit temperature and thermal gradient) of vitrification. Using a dedicated control volume numerical model of TRC, simulation of the casting of 2 mm thick Vit 1 (Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5) alloy strip shows that the acceptable casting speeds are in the range 2.5 to 3.5 cm/s. The effects of varying strip thickness and strip-roll heat transfer coefficient (HTC) on this casting window are assessed. The differences between modelling of conventional alloy solidification and metallic glass formation are presented.     

近液相线半连续铸造法制备半固态铝合金的研究进展

介绍半固态铝合金的各种制备工艺，分析了近液相线半连续铸造法制备半固态铝合金的现状与发展趋势，探讨半固态初生球状晶形成机理的研究现状，指出近液相线半连续铸造法具有广阔的应用前景。     

新型铜-稀土系引线框架材料研制

采用熔铸法制备了多种Cu—RE和Cu—Cr—RE合金，并利用电子显微镜、能谱分析、X射线衍射、定量金相、涡流导电仪、显微硬度计等一系列现代分析测试手段，考察了相关的制备工艺、热处理制度以及力学和电学性能，分析了稀土对铜合金组织和性能的影响规律。     

钒基固溶体贮氢合金研究现状

贮氢合金是MH/Ni电池技术的核心,为了满足镍氢电池作为动力电池的要求,开发低成本、高功率、高稳定性的贮氢合金,近年来人们在进一步提高其电化学性能方面做了大量工作。钒基固溶体贮氢合金是近年来开发的一种新型高性能贮氢材料。介绍了氢钒反应特点和钒基固溶体合金的制备方法,对无电化学活性的基质合金,用元素取代、合成复合合金和多相合金等多种方法,得到一些性能较好的负极材料。并对钒基固溶体贮氢合金的研究及开发现状进行了综述,指出了固溶体合金的研究方向。     

Highly ameliorated gaseous and electrochemical hydrogen storage dynamics of nanocrystalline and amorphous LaMg12-type alloys prepared by mechanical milling

Nanocrystalline and amorphous LaMg12-type alloy-Ni composites with a nominal composition of LaMg11 Ni+x wt.% Ni (x=100, 200) were synthesized via ball milling.The influences of ball mill-ing duration and Ni adding amount x on the gaseous and electrochemical hydrogen storage dynamics of the alloys were systematically studied.Gaseous hydrogen storage performances were studied by a differential scanning calorimeter and a Sievert apparatus.The dehydrogenation activation energy of the alloy hydrides was evaluated by Kissinger method.The electrochemical hydrogen storage dynam-ics of the alloys was investigated by an automatic galvanostatic system.The H atom diffusion and ap-parent activation enthalpy of the alloys were calculated.The results demonstrate that a variation in Ni content remarkably enhances the gaseous and electrochemical hydrogen storage dynamics perform-ance of the alloys.The gaseous hydriding rate and high-rate discharge (HRD) ability of the alloys ex-hibit maximum values with varying milling duration.However, the dehydriding kinetics of the alloys is always accelerated by prolonging milling duration.Specifically, rising milling time from 5 to 60 h makes the hydrogen desorption ratio (a ratio of the dehydrogenation amount in 20 min to the saturat-ed hydrogenation amount) increase from 57% to 66% for x=100 alloy and from 57% to 70% for x=200.Moreover, the improvement of gaseous hydrogen storage kinetics is attributed to the descending of dehydrogenation activation energy caused by the prolonging of milling duration and growing of Ni content.     

快淬纳米晶/非晶Mg2-xLaxNi (x=0～0.6)合金的贮氢动力学

为了改善Mg2Ni型合金气态及电化学贮氢动力学性能,用La部分替代合金中的Mg,用快淬技术制备了Mg2-xLaxNi(x=0,0.2,0.4,0.6)合金,用XRD,SEM,HRTEM分析了铸态及快淬态合金的微观结构;用自动控制的Sieverts设备测试了合金的气态贮氢动力学性能,用程控电池测试仪测试了合金的电化学贮氢动力学.结果发现,快淬无La合金具有典型的纳米晶结构,而快淬含La合金显示了以非晶相为主的结构,表明La替代Mg提高Mg2Ni型合金的非晶形成能力.La替代Mg明显地改变Mg2Ni型合金的相组成.当La替代量x=0.4时,合金的主相改变为(La,Mg) Ni3+ LaMg3.合金的气态及电化学吸放氢动力学对La含量及快淬工艺敏感,La替代使合金的吸氢动力学降低,但适量的La替代可以明显改善合金的放氢动力学及高倍率放电能力.适当的快淬处理可以提高合金的气态及电化学贮氢动力学,但获得最佳贮氢动力学的快淬工艺与合金的成分密切相关.     

NdFeB合金氢爆过程中的孕育机理研究

对N dF eB合金铸块和铸片的氢爆研究表明,N dF eB合金在吸氢前均明显存在孕育期,且孕育期的长短与温度和氢气压力有关。为了能清楚地解释N dF eB合金的孕育现象,提出了N dF eB合金孕育过程的微观机理:氢气在N dF eB合金表面首先发生物理吸附,再转变为化学吸附,然后氢原子扩散进入富N d相导致吸氢开始。该理论很好地解释和展现了N dF eB合金吸氢前的孕育现象和过程。同时,N dF eB合金氢爆过程中温度和氢气压力对孕育的影响规律也从吸附理论的角度得到了很好的解释。