低Co贮氢合金ReNi3.5Co0.3Mn0.3Al0.4Fe0.5-xSnx(x=0～0.4)的相结构和电化学性能

对比研究了铸态和退火态ReNi3.5Co0．3Mn0．3Al0．4Fe0.5—xSnx(x＝0—0．4)贮氢合金的相结构和电化学性能。XRD分析表明，铸态和退火态的无Sn合金均为单相CaCu5型结构；而在含Sn合金中，除CaCu5型结构的主相之外，还存在有LaNiSn第二相，且第二相的含量随合金Sn含量(x)的增加而增多；退火处理可以减少含Sn合金中第二相的含量。电化学测试表明，Sn含量对铸态合金的活化性能没有影响，但Sn含量的增加会导致合金的放电容量降低；退火处理可使Sn含量x≤0．2的合金的活化次数及放电容量略有增加，但使Sn含量更高(x＞0．2)的合金的活化性能及放电容量明显降低。随Sn含量x的增加，铸态合金的放电电位平台、高倍率放电性能及循环稳定性均有所降低；退火处理能显著改善含Sn合金的放电电位平台和循环稳定性，但使合金的高倍率放电性能进一步降低。     

非化学计量比贮氢合金及其电极特性

对贮氢合金M1Ni3.55 xCo0.75Al0.3Mn0.4(0≤x≤0.6)的结构、组织、电化学性能和P－C－T特性进行了研究。结果表明,除了x=0.6的合金外,随着x的增大合金的点阵常数a值减小、c值增大,c/a值和单胞体积也随之增大,而x=0.6时合金体积反而减小。同时随着x的增大,合金中Ni并没有出现明显偏析,而是促进了B侧其它合金元素尤其是Mn和Al的偏析。x的增大,放电容量降低,充放电循环稳定性只略有下降,但活化性能却明显改善,P－C－T曲线平台压升高。     

低成本富镧贮氢合金的相结构及其电化学性能

采用感应熔炼法制备低成本富镧贮氢合金MLNi4.0-xCo0.4Mn0.3Al0.3Cux.通过X射线衍射（XRD）、交流阻抗和恒电流充放电法等手段对合金性能进行表征。结果表明：Cu部分取代Ni后，合金仍保持单相CaCu5结构，随着X的增加，合金晶格参数a值和晶胞体积减小，c值和c／a值增大：当x=0．2时，合金电极最高放电容量为327．1mAh/g铜的添加能降低舍金的显微组织硬度，提高合金电极的循环稳定性，经200次循环后的电极容量保持率（C200／Cmax）均在83％以上（X=0．2）；高倍率放电性能（HRD）有所下降，但x=0．4时，HRD300仍达到89．6％。     

Ti对Zr1-xTixMn0.4Cr0.4Ni1.2结构和电化学性能的影响

采用真空电弧炉（在氩气保护下）制备Zr1-xTixMn0.4Cr0.4Ni1.2贮氢合金，通过XRD、SEM和恒流充放电研究了合金的相结构、形貌和电化学性能。结果表明：Ti为C14型Laves相的稳定性元素，随着Ti含量的增加，C14型Laves相增多，C15型Laves相减少。当x=0．1时，合金综合性能最好，表现出良好的活化性能、循环稳定性能和高倍率放电特性，在放电电流300mA／g的条件下，充放电循环50次，合金保持稳定的放电容量。当X〉0．1时，合金放电容量下降。Ti的加入使合金氢化物稳定性降低，加入少量Ti，有利于合金的放电容量的提高和高倍率放电性能的提高。     

Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx（x=0,0.1,0.2,0.3）储氢合金的微观结构和电化学性能

采用XRD、SEM-EDS等方法对Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)储氢合金的微观结构及电化学性能进行了表征。XRD分析结果表明Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)储氢合金由BCC结构的V基固溶体主相和少量的C14Laves第二相组成。SEM-EDS分析结果表明,V基固溶体主相为树枝晶结构,C14Laves相呈网格状沿着主相晶界析出。电化学测试结果表明,Ti0.4Zr0.1V1.1Mn0.5Ni0.4Crx(x=0,0.1,0.2,0.3)氢化物电极在303K下,随Cr含量的增加,最大放电容量分别为574.6mAh/g、418.8mAh/g、368.8mAh/g和322.9mAh/g。当x=0.3时,合金电极在333K下的最大放电容量达到了824.1mAh/g。Cr的添加显著提高了合金电极的高倍率放电性能和循环寿命,40次充放电循环后Ti0.4Zr0.1V1.1Mn0.5Ni0.4Cr0.3合金电极的容量保持率为62.3%。     

Cu对MI(NiAlMnCoCu)5.1贮氢合金电化学性能的影响

研究了Cu含量对MINi3.9-xCo0.4Al0.2Mn0.4Cux贮氢合金的电化学性能的影响。实验发现：随着Cu含量x从0增加至0．3，合金的活化性能仍保持在2—3次；但合金的最大放电容量从344mAh／g下降到310mAh／g；高倍率放电性能均在81%以上；合金的循环寿命随着Cu含量的增加而有所提高的。实验表明，合金中加入适量的Cu，可有效的改善合金的循环寿命。     

La1.5Mg0.5Ni7-xCux(x=0.1～1.2)贮氢合金电化学性能的研究

研究了Ce2Ni7型贮氢合金La1.5Mg0.5Ni7-xCux（x=0.1-1.2）的组织结构和电化学性能。当X=0．1—0．6时Cu元素部分替代Ni后可形成La2Ni7型相，x≥0．9时，合金中则有少量的未知相析出。合金MH电极电化学研究表明，随Cu元素量的增加，合金电极的最大放电容量从380mAh／g（x=0．1）下降至340mAh／g（x=1．2）；当x=0．3～0．9时合金电极的循环寿命较x=0．1时有一定的改善，合金电极交换电流密度（I0）和极限电流密度（I1）均以x=0．6为转折点先减小后增大。电极反应的动力学性能依Cu0．1〉Cu0．3〉Cu1．2〉Cu0．9〉Cu0．6的次序递减。     

锂离子电池正极材料Li(MnxFe1-x)PO4的合成及电化学性能的研究

采用高温固相法合成了组成为Li（MnxFe1-x）PO4（x=0、0．2、0．4、0．6、0．8、1．0）的锂离子电池正极材料。通过对合成样品的XRD、SEM及电化学性能（循环性能,大电流放电性能）的研究表明,少量Mn的掺杂未影响到LiFePO4的晶体结构,但显著改善了它的电化学性能。Li（Mn0.2Fe0.8）PO4与LiFePO4材料相比有更好的电化学性能,在低放电倍率（电流密度为20mA／g）时,放电容量为150mAh／g,当放电倍率提高到2C时,放电容量仍可达113mAh／g,且循环性能良好。     

球磨Zr7Ni10合金提高Zr基电极合金的电化学性能

为了提高合金的放电容量和高倍率放电性能，通过球磨Zr7Ni10合金对Zr0．5Ti0．5Mn0．7V0．2Co0．1Ni1．2合金表面进行改性，并研究了不同Zr，Ni10量和球磨时间对合金的相结构和电化学性能的影响。当采用8％（质量分数）Zr，Ni10进行球磨1h后，合金仍保持晶态，在50mAh／g电流条件下经过9次循环达到最大放电容量266mAh／g，比未球磨合金提高了约20％，而且在300mA／g电流条件下仍能保持最大放电容量的85%。随着球磨时间的增加，合金逐渐转为非晶态，合金的放电容量也迅速降低。非晶化合金在800℃进行热处理后大部分重新晶化，经过22次循环达到最大放电容量200mAh／g。     

金属钴对储氢合金电极的表面修饰研究

运用真空蒸镀法时MH／Ni电池储氢合金电极进行了镀覆金属钴的表面修饰,测试了电池的放电容量、高倍率放电性能、循环寿命和充电时的内压,利用XPS和XRD时电极进行了表面和结构分析。实验结果表明,运用该方法对电极进行表面修饰可以降低电池内阻,提高电池的放电容量和放电电压,极片经过修饰的电池,5C（8．5A）放电容量提高了120mAh,放电平台电压提高了约0．05V,内阻降低了19．3％。极片经过表面镀钴后,显著改善了电池的循环性能,电池500周循环后的放电容量仍为初始容量的94．09／6,同时,电池在充电时的内压有了明显的降低,充电效率有了较大的提高。     

Synthesis and electrochemical properties of modification LiNi1/3Co1/3Mn1/3O2 cathode materials for Li-ion battery

The layered LiNi1/3CO1/3Mn1/3-xMg(x)O2 (x = 0, 0.01, 0.03, 0.05) cathode materials were prepared by solid state reaction, then copper oxide was coated on the product. The structures, morphologies and electrochemical properties of the LiNi1/3Co1/3Mn1/3-xMg(x)O2 and CuO-coated LiNi1/3Co1/3Mn1/3-xMg(x)O2 were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical tests. The results showed that the electrochemistry properties and cycle performance of magnesium doped LiNi1/3Co1/3Mn1/3O2 and CuO-coated LiNi1/3Co1/3Mn1/3-xMg(x)O2 materials were improved. The optimal doping content of Mg was x = 0.03 in the LiNi1/3Co1/3Mn1/3-xMg(x)O2 samples to achieve high discharge capacity and good cyclic stability, and the first discharge special capacity was 158.5 mAh/g at 0.2 C in the voltage of 2.5-4.3 V, then CuO-coated LiNi1/3Co1/3Mn1/3-0.03Mg0.03O2 was investigated. The electrode reaction reversibility and electronic conductivity were enhanced through Mg-doped and CuO-coated.     

Einfluß der Wärmebehandlung auf die Schwingfestigkeitseigenschaften der Legierung AlMgSi 0,7

Influence of Heat Treatment on the Fatigue Behaviour of 6005A Aluminium Alloy The influence of industrial heat treatment on the fatigue behaviour of 6005A Aluminium alloy has been investigated. By variation of the cooling rate from solution temperature and holding time at room temperature the size of precipitates improving strength and the width of precipitation free zones at grain boundaries may be altered independently from each other. Increasing the size of precipitates and the width of the precipitation free zones will decrease the tensile properties. In the high cycle fatigue region minor fatigue properties result from a significant broadening of the precipitation free zones, which enhance deformation and crack initiation at the grain boundaries. Coarsening the precipitates has no influence on fatigue behaviour, before crack initiation has taken place, but reduces fatigue crack propagation rate and by this improves the total lifetime.     

Influence of grain size and precipitation on hot ductility of microalloyed steels

Abstract

The influence of grain size on the hot ducility of microalloyed steels (C–Mn–Al, C–Mn–V–Al, and C–Mn–Nb–Al) has been determined by heating them above their solution temperatures and cooling to the test temperature of 850°C. The C–Mn–Al steel showed excellent hot ductility which was independent of grain size. Dynamic recrystallization readily occurred and there was no evidence for AlN precipitation. Marked dynamic precipitation occurred during the tensile test for vanadium- and niobium-containing steels but this did not vary significantly with reheating temperature, provided complete dissolution of the precipitates had occurred. Isolating the influence of grain size from that of precipitation in these steels showed that a change in grain size from 150 to 300 μm reduced the reduction of area values by 15–20%. Precipitate distribution was also varied by heating to temperatures in the range 850–1330°C and tensile testing at 850°C. When present before testing at the γ grain boundaries in the form of a fine grain-refining precipitate, AlN reduced the hot ductility in the C–Mn–Al steel and delayed the onset of dynamic recrystallization. Coarser precipitates produced by raising the reheating temperature allowing dynamic recrystallization to occur gave improved ductility. For the niobium- and vanadium-containing steels, precipitate distributions which were in a coarse randomly precipitated form gave the best hot ductility. These occurred with the niobium-containing steel when heated to 1100°C and more generally in the vanadium-containing steel throughout a wide temperature range. The worst precipitate distribution occurred in the niobium containing steel when the NbCN was taken into solution before testing and reprecipitated in a fine form at the γ grain boundaries and within the matrix during the test.

MST/490     

AB2型LaMgNi3.7M0.3(M=Ni、Al、Mn、Co、Sn、Cu)贮氢合金的晶体结构及电极性能

系统研究了LaMgNi3.7M0.3（M=Ni、Al、Mn、Co、Sn、Cu）合金的组织结构和电化学性能。XRD和电子探针显微分析（EPMA）结果表明：该系列合金主相均为LaMgNi4相，其中含Mn、Cu和Co元素在LaMgNia合金相中有一定的固溶度，LaMgNi3.7Sn0.3合金中的Sn元素主要以LaNiSn相析出；XRD全谱拟合分析表明：LaMgNi3.7Al0.3中Al元素主要占据在LaNi5相的3g位置。合会化元素在LaMgNi4相中的固溶度从大到小的顺序是Mn〉Cu〉Co〉Al〉Sn。电化学实验表明，该系列合金经1～3次循环即可活化，最大放电容量由245．2mAh／g（M=Sn）变化至293．2mAh／g（M=Co），但合金电极的循环稳定性均较差。合金电极的高倍率放电性能（HRD900%）从大到小依次为Al〉Sn〉Cu〉Mn〉Ni〉Co，其中氢原子在合金中的扩散时合金电极的高倍率放电性能起主要作用。     

锂离子电池正极材料LiNi0.5FexMn1.5-xO4的电化学性能

以醋酸锂、醋酸锰、醋酸镍、草酸铁为原料,采用溶胶凝胶法制备出了4.6 V高电位材料LiNi0.5-FexMn1.5-xO4。合成化学计量比为n(Li)∶n(Mn)∶n(Ni)∶n(Fe)=1.3∶1.5-x∶0.5∶x(x=0,0.02,0.03,0.04)。在空气条件下于450℃下煅烧6h,再于800℃下烧结18h。对合成的材料用X射线衍射仪分析晶体结构和用扫描电镜(SEM)观察微观形貌,对电池进行首次充放电测试和循环效率测试。实验结果表明,LiNi0.5FexMn1.5-xO4三元正极材料为立方晶系,Fd3m空间群。以其为正极材料组装的锂离子电池在x=0.03时,充放电比容量为126mA·h·g-1。     

Improved Electrochemical Performance of Orthorhombic LiMn1-xCrxO2 Synthesized by Hydrothermal Method

Single phase chromium-substituted orthorhombic LiMn1-xCrxO2 (0≤x≤0.05) were successfully synthesized by hydrothermal treatment of Mn2O3, Cr2O3 and lithium hydroxide aqueous solution. Structure and morphologies of the o-LiMn1-xCrxO2 were characterized by X-ray diffraction and transmission electron microscopy.Compared to the particle size of o-LiMnO2 ranging from 50 to 150 nm, the Cr-doped one is larger with about 500 nm, which is agglomerated by small grains. There are high stacking faults in nanosized grains that cause easier phase transformation from the orthorhombic to the spinel-like structure on cycling. High-resolution transmission electron microscopy image analysis of electrochemically cycled o-LiMn1-xCrxO2 (x=0, 0.05)samples showed that the nanodomain structure in o-LiMn0.95Cr0.05O2 was comparatively perfect to that in o-LiMnO2. Particle agglomeration and the relatively perfect crystal structure are two key factors for improving cycle performance of o-LiMn0.95Cr0.05O2. The obtained o-LiMn0.95Cr0.05O2 can reach a maximum discharge capacity of 174 mA·h·g-1 at 0.1 C rate in seventh cycle. The discharge capacity fade rate of the samples decreased with increasing Cr amount. Furthermore, o-LiMn0.95Cr0.05O2 gives a highest discharge capacity of 150 mA·h·g-1 at a high current rate of 0.5 C, and retains 130 mA·h·g-1 after 40 cycles.     

Effect of Stoichiometry on Properties of Rare-Earth-Based Hydrogen Storage Alloy for Nickel-Metal Hydride Secondary Battery

Effect of stoichiometry on microstructures, electrochemical properties and PCT characteristics of the alloys MI(Ni0.71Co0.15-Al0.06Mn0.08)x (MI=Lanthanum-rich Michmetal, x=4.6~5.2) have been investigated. The lattice constants a, c, and cellvolumes of non-stoichiometric alloys are bigger than those of the stoichiometric alloy. With the increasing stoichiometry x,the value of a decreases, and the value of c and cell volume increases except for those of the stoichiometric alloy; the plateaupressure of PCT curve, discharge capacity and cycling stability all increase. The alloy with x=5.2 shows the highest dischargecapacity and the best cycling stability among the studied alloys.     

RE对Mg-8Zn-4Al-0.3Mn镁合金阻尼性能的影响

研究了 RE对Mg-8Zn-4Al-0.3Mn镁合金阻尼性能的影响.研究表明,加入RE后降低了合金低温下的阻尼性能,但明显提高了其在高温下(≥120℃)的阻尼性能.高温下,加入1.0%RE的合金表现出了最高的阻尼性能.由于高温下合金中相界面的软化及粘性滑动,四种合金在高温下均存在一个温度内耗峰,只是出现的温度不同.RE的加入推迟了温度内耗峰出现的温度.分析认为,加入RE后合金的阻尼机制主要是位错机制和界面机制.可动位错密度越高,晶粒越细,晶界和相界越多,阻尼性能越好.     

快淬工艺对低钴AB5型贮氢合金电化学性能的影响

研究了快淬工艺对稀土基低钴AB5型LaxMm1-x（NiMnSiAlFe）4．7Co0．2（x=0、01）贮氢合金的电化学性能及其微观结构的影响。研究结果表明,快淬改善了两种合金的循环稳定性,其主要原因是快淬使合金的晶胞体积增大,且使合金的晶粒细化;快淬对La含量x=0合金的循环寿命的增加幅度尤其明显,主要是因为快淬使该合金的晶粒更为细小。La替代Mm使合金的放电容量提高,其原因是La替代Mm抑制了第二相Ce2Ni7相的形成,并使合金的晶胞体积增大。     

A TEM investigation of M23C6 carbide precipitation behaviour on varying grain boundary misorientations in 304 stainless steels

Transmission electron microscopy (TEM) along with electrochemical potentiokinetic reactivation (EPR) testing was performed on different grades of 304 stainless steel (0.01, 0.025, 0.05, and 0.07%C) in order to assess the sensitization and precipitation behaviour on different grain boundary misorientations. The materials were heat treated at 670°C for 50 h to subject the materials to the sensitization regime. The EPR data and TEM observations revealed that when the amount of carbon was increased the degree of sensitization increased along with the density of precipitates. Large angle misorientations (>15°) were prevalent in all the carbon content materials and the {1 1 0} grain surface orientation was found to be the major texturing orientation. The steels with lower carbon contents nucleated a few small precipitates on high angle grain boundaries, while larger amounts of carbides were observed on lower angle grain boundaries for the higher carbon contents. It was deemed that higher carbon contents required lower energies to nucleate and grow precipitates. A carbon content threshold was found (above 0.05% C) in which precipitates fully saturate the grain boundary. Precipitation followed the energies of different types of boundaries. The highest energy boundary (general random grain boundary) nucleated precipitates first, then precipitation followed on non-coherent twin boundaries, and was not observed on coherent twin boundaries. A critical nucleation energy, gb(crit.), was therefore found to exist at which precipitation will occur on a boundary. This value was found to be in the range of 16 mJ m-2相似文献