Ml0.75Mg0.25Ni3.5-x Alx合金储氢性能及电化学性能研究

在Ar气保护下,采用悬浮熔炼方法制备Ml0.75 Mg0.25 Ni3.5 -xAlx(x=0.05 ～0.25)合金,系统研究Al部分取代Ni对合金的相结构、吸放氢性能和电化学性能的影响.结果表明,合金的相结构主要由具有六方CaCu5结构的(La,Pr) Ni5相、(La,Pr) Mg2Ni9相和(La,Nd)2 N...     

Microstructural evolution and performance of hydrogen storage and electrochemistry of Co-added La0.75Mg0.25Ni3.5−xCox (x = 0, 0.2, 0.5 at%) alloys

Microstructure, hydrogen storage and electrochemical performances of Co-added La_(0.75)Mg_(0.25)Ni_(3.5_x)Co_x(x = 0,0.2, 0.5 at%) alloys are studied. XRD and rietveld refinement results suggest that the samples are mainly composed of(LaMg)Ni_3,(LaMg)_2Ni_7 and LaNi_5 phases, Co substitution for Ni changes the phase abundance,but not the phase composition. With the rising of Co content, the amount of(LaMg)_2 Ni_7 phase decreases, but the amount of LaNi_5 phase increases, while the amount of(LaMg)Ni_3 phase firstly increases and then decreases.The alloys reversibly absorb and desorb hydrogen at 298 K smoothly. When Co content is 0.2 at%, the hydrogen absorption capacity reaches the maximum value of 1.14 H/M, and the absorption capacities reach 1.09 H/M and 1.03 H/M in the first minute at 298 K and 323 K, respectively. Electrochemical performance measurement results show that La_(0.75)Mg_(0.25)Ni_(3.5-x)Co_x alloys are completely activated within 2 cycles, and the cyclic stability of La_(0.75)Mg_(0.25)Ni_(3.3)Co_(0.2) alloy approaches 63.7% after 100 charge/discharge cycles, which is higher than that(S_(100) = 60%) of La_(0.75)Mg_(0.25)Ni_(3.0)Co_(0.5) alloy. Thus, the La_(0.75)Mg_(0.25)Ni_(3.3)Co_(0.2) alloy exhibits optimum comprehensive properties of hydrogen storage and electrochemistry.     

Tix-Nb1-x合金结构及弹性性质的第一性原理研究

本文基于密度泛函理论的第一性原理计算方法详细地计算了高温高压下不同铌含量对Tix-Nb1-x (x=0, 025, 05, 075,1)二元合金的能量和结构的影响。结果表明,零温零压下不同铌含量下的三种稳定的合金组成结构分别为六角密堆结构Nb025Ti075,体心立方结构 Nb05Ti05和体心立方结构Nb075Ti025,所得的稳定的合金结构晶格参数与相关的实验值和理论值符合的很好。这样, 分别计算了在压强60GPa范围内的稳定的合金结构的弹性性质和弹性模量。     

Na_(3.3)Zr_(1.65-X)Ti_XSi_(1.9)P_(1.1)O_(11.5)系统的相组成及性能

通过高温（１１７３—１４７３Ｋ）固相反应．制备了钠快离子导体ＮＡ３．３Ｚｒ１．６５－ＸＴｉＸＳｉ１．９ Ｐ１．１Ｏ１１．５系统中Ｘ＝０－１．６５的一系列合成物，研究了该系统的相变情况，探明了在ｘ＝０．５－０．９ 的组成范围内可制得ＮＡＳＩＣＯＮ单相．其中电导性最好的是Ｘ＝０．６的合成物．在６２３ｋ时它的电导 率为１８．９Ｓ·ｍ－１，在４７３—６７３Ｋ温区里其电导激活能为４１．７ＫＪ／ｍｏｌｅ．     

Ti_(62)Zr_(17)Cu_6Ni_(15)合金晶化实验分析

对Ti6 2 Zr1 7Cu6 Ni1 5非晶合金原始样品进行了退火晶化处理和激波晶化处理 ,对样品作了XRD分析并重点对样品进行了差示扫描量热分析 (DSC)以及动力学分析 .看到了许多有趣的现象并得到了一些有价值的动力学参数     

机械合金化法制备Cu-Ti-Zr基非晶合金

采用机械合金化法成功制备Cu40Ti60-xZr(x=0,10,30,50)非晶合金.研究Cu-Ti-Zr合金粉末由晶态向非晶态转变过程中的组织结构变化,探讨非晶合金的形成机制,以及非晶合金的热稳定性和晶化产物.结果表明,非晶合金直接从初始元素得到,在反应过程中没有金属间化合物出现,非晶化过程可以由间隙扩散模型来解释.Cu40TixZry非晶粉末的DSC分析表明,随着Ti含量的降低和Zr含量的升高,非晶粉末的晶化温度Tx逐渐升高,对非晶粉末在相应的Tx温度附近退火15min后发现,Cu40Ti30Zr30合金没有析出相,Cu40Ti1Zr50析出了Zr2Cu,Cu4Ti和少量的一些未知相.     

Effect of heat treatment on hydrogen storage properties and thermal stability of V68Ti20Cr12 alloy

Effect of heat treatment on the crystal structure, microstructure, hydrogen storage properties and thermal stability of V68Ti20Cr12 alloy prepared by arc-melting was studied in this work. It was found that both the as-cast and annealed (973 K/72 h) V68Ti20Cr12 alloys consisted of a single body-centered cubic (bcc) phase. After heat treatment, the hydrogen absorption/desorption kinetic characteristics of the as-cast alloy was improved greatly due to the homogeneous composition and perfect structure. The mechanism of hydrogen absorption/desorption process in the as-cast and annealed alloys was further investigated according to the Johnson-Mehl-Avrami (JMA) equation. The hydrogen absorption process of the as-cast and annealed alloys would be controlled by the one-dimensional diffusion process, while the hydrogen desorption process in the as-cast and annealed alloys was dominated by the geometrical contraction model. The pressure-composition-temperature (PCT) measurements show that the plateau pressure of the annealed alloy becomes comparatively flat. Furthermore, the activation energies of the dehydrogenation in the as-cast and annealed alloys were calculated using the Kissinger method, indicating that heat treatment is a very beneficial way to improve hydrogen absorption/desorption kinetics of the alloy.     

机械合金化法制备Co-Zr非晶软磁合金粉末的研究

研究了Co-Zr二元相图上4个共晶点成分配方Co90Zr10、Co53Zr47、Co35Zr65和Co21Zr79在球磨条件下的非晶态合金形成能力．分析结果表明，4种配方在一定的球磨时间内都能形成非晶态合金，非晶形成时间由短到长的合金组分依次为Co35Zr65、Co21Zr79、Co90Zr10和Co53Zr47，其中非晶形成能力最强的是Co35Zr65．作为选择非晶态合金成分的判据来说，对于机械合金化法(MA)法，Davies的共晶线准则比较合适．但若球磨时间继续延长，No．3特别是No．4样品球磨产物中出现明显的纳米微晶CoZr2金属间化合物．说明CoZr合金系随着w(Zr)的增加，金属问化合物形成能力增加，这与Co和Zr的晶体结构有关．球磨时间对非晶的形成有重要影响，球磨时间过长，使形成的非晶态合金反而向晶体转化．     

非晶态合金(Fe_(100-x)M_x)_(83)B_(17)和Zr_(100-x)M_x的杨氏模量

用超声波脉冲透射技术获得了三元非晶态合金(Fe_(100-x)M_x)_(83)B_(17)和二元非晶态合金Zr_(100-x)M_x的声速,并确定了它们的杨氏模量。对于前者合金元素M指Cr,Mo,W,Zr和Co;对于后者指Fe,Ni和Co。文中讨论了声速与组分的原子百分数含量x之间的关系,并讨论了近程有序,合金元素密度以及不同尺寸原子之间的随机堆砌引起的致密化等对声速的影响。     

Hydrogen storage and low-temperature electrochemical performances of A2B7 type La-Mg-Ni-Co-Al-Mo alloys

The effect of Mo-addition on hydrogen storage and low-temperature electrochemical performances of La-Mg-Ni-Co-Al alloys is investigated. The alloys were synthetized via vacuum induction melting followed by annealing treatment at 1123 K for 8 h. The major phases in the annealed alloys are consisted of (La, Mg)2Ni7, (La, Mg)5Ni19 and LaNi5 phases. Mo-addition facilitates phase transformation of LaNi5 into (La, Mg)2Ni7 and (La, Mg)5Ni19 phases. Hydrogen absorption/desorption PCI curves indicates that the hydrogen storage capacity of the alloy increases remarkably with the addition of Mo. Furthermore, the La0.75Mg0.25Ni3.05Co0.2Al0.05Mo0.2 alloy shows excellent hydriding/dehydriding kinetics with a higher capacity, requiring only 100 s to reach its saturated hydrogen capacity of 1.58 wt% at low temperature of 303 K, and releasing 1.57 wt% hydrogen within 400 s at 338 K. Electrochemical experiments manifest that the Mo-added alloy electrode has perfect activation properties and the maximum discharge capacity. The low-temperature dischargeability shows that the La0.75Mg0.25Ni3.05Co0.2Al0.05Mo0.2 alloy exhibits the excellent low-temperature discharge performance, and the maximum discharge capacity is improved from 231.0 to 334.6 mAh/g at 253 K. The HRD property of the alloy electrode is enhanced, suggesting that Mo enhances the kinetic ability at low-temperature.     

[(NaSb_9W_(21)O_(86)~(18-))/PAH]无机-有机复合薄膜修饰电极的制备及其电化学研究

首次用多金属氧酸盐阴离子[NaSb9W21O86]18-(Sb9W21)做修饰剂,通过电化学技术结合层接层自组装方法制得了[(NaSb9W21O8168-)/PAH](PAH:聚烯丙基胺盐酸盐)复合薄膜修饰玻碳电极(GCE),并研究了该电极在酸性水溶液中的电化学行为.结果表明:该修饰电极充分保持了Sb9W21的电化学活性;对亚硝酸根和溴酸根的还原具有良好的电催化效果.     

Zr-Cu-Al三元合金大块金属玻璃的形成能力及热稳定性

用水冷铜模吸铸的方法制备了直径为3mm的Zr85-xCuxAl15（x=25、30、35、40和45）合金棒．用X射线衍射（XRD）、差分扫描量热（DSC）和差分热分析（DTA）测试,结果表明：Zr55Cu30Al15和Zr50Cu35Al15,为完全非晶,且Zr50Cu35Al15为近共晶成分,其玻璃形成能力和热稳定性最佳．运用Miedema半经验模型对该合金系的非晶形成焓进行了理论分析计算,其结果与实验基本符合．     

Cu,Zr对Al-Ni-Zr-Cu-Y非晶合金的形成和热稳定性的影响

采用单辊旋淬技术,在真空条件下制备了快速凝固Al85Ni10Zr3Y2四元合金条带和Al80Ni10Zr8-xCuxY2(x=1,2,3,5)五元合金条带.利用X射线衍射及差热分析对条带进行了研究.结果表明,w(Cu)和w(Zr)对该合金系的非晶形成能力及热稳定性有显著影响,并且非晶合金的形成对这两种元素的质量分数很敏感.当w(Cu)和w(Zr)其中一种达到一较大值时,可以形成非晶合金或是以非晶相为主的合金,否则将只能得到晶体相.另外,Al80Ni10Zr7Cu1Y2,Al80Ni10Zr3Cu5Y2合金系具有较强的非晶形成能力,可形成完全非晶或以非晶为主体和部分晶体的复相材料.     

稀土镧和钛取代镁基储氢合金电极电化学性能的研究

利用机械合金化方法制成了MgNi,Mg0.7Ti0.3Ni和Mg0.7Ti0.225 La0.075Ni非晶态镁基合金,XRD表明球磨100 h后已形成非晶;电化学容量测试表明:在此实验条件下添加Ti,La元素改善了电极的循环稳定性能.其中,La的取代提高了合金的抗腐蚀性能和合金的电化学氧化还原反应的可逆性能,进而提高...     

快速凝固Al85Ni8Zr3Cu2Y2非晶材料的形成及热稳定性分析

采用旋铸急冷工艺分别在大气和真空环境中获得了Al85Ni10Zr5和Al85Ni8Zr3Cu2Y2韧性非晶合金带材,利用X射线衍射和示差扫描量热仪(DSC)对条带的显微结构及热稳定性进行了分析.结果表明,无论在真空还是在大气条件下,Y,Cu元素的添加都提高了Al85Ni10Zr5合金的非晶形成能力及热稳定性.研究发现,合金成分及冷却速率对非晶的形成起了重要作用,而甩带环境对Al Ni Zr合金系的非晶形成影响不大.     

Tb_(0.3)Dy_(0.7-x)Pr_x(Fe_(0.9)Al_(0.1))_(1.95)合金的磁性、磁致伸缩和穆斯堡尔谱

系统研究了室温下Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.2,0.25,0.3,0.35)合金中稀土元素Pr替代Dy对磁性、磁晶各向异性、磁致伸缩和穆斯堡尔谱的影响.对磁化强度和磁致伸缩的测量发现,少量Pr替代有助于降低磁晶各向异性;随着替代量x的增多磁致伸缩减小,x>0.2时超磁致伸缩效应消失.然而,x=0.1时合金的磁致伸缩略大于没有替代的,而且磁致伸缩随磁场更易趋于饱和;同时发现,随着Pr替代量x的增加,饱和磁化强度和Curie温度单调下降,而内禀磁致伸缩急剧增大.多功能磁性测量系统PPMS的研究和Mossbauer效应表明,随着Pr含量的增加,合金中的易磁化轴可能在{110}面上绕主对称轴作微小转动,发生自旋重取向.与Al元素替代效应相比,Pr替代Dy对自旋重取向的影响相对较小.     

Multiscale structures of Zr-based binary metallic glasses and the correlation with glass forming ability

Thermal behaviors and structures of three Zr-based binary glass formers, Zr50Cu50, Zr64Cu36 and Zr64Ni36, were investigated and compared using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), high energy X-ray diffraction (XRD) and small angle X-ray scattering (SAXS). The high energy XRD results show that the bulk glass former Zr50Cu50 has a denser atomic packing efficiency and reduced mediumrange order than those of marginal glass formers Zr64Cu36 and Zr64Ni36. Based on TEM observations for the samples after heat treatment at 10 K above their crystallization onset temperatures, the number density of crystals for Zr50Cu50 was estimated to be 1023–1024 m?3, which was four-orders higher than that in Zr64Cu36 and Zr64Ni36 metallic glasses. SAXS results indicate that Zr50Cu50 has higher degree of nanoscale inhomogeneities than those in Zr64Cu36 and Zr64Ni36 at as-cast state. The observed multiscale structures are discussed in terms of the phase stability and glass-forming ability of Zr-based binary glass formers.     

Micro-alloying of yttrium in Zr-based bulk metallic glasses

The effect of yttrium addition on the glass-forming ability(GFA) and mechanical properties of the Zr-based (Zr_(0.525)Al_(0.1)Ti_(0.05)Cu_(0.179)Ni_(0.146))_(100-x)Y_x and(Zr_(0.55)Al_(0.15)Ni_(0.1)Cu_(0.2))_(100-x)Y_x(x=0,0.2,0.4 0.6,1,2) alloys was studied.Micro-alloying of 0.6%yttrium enhances the room temperature ductility as well as the GFA of the Zr-based alloys.The mechanism of enhancing the GFA and room temperature ductility was analyzed.It is indicated that proper yttrium addition stabilizes the...     

Enhancing thermoelectric performance of Cu-modified Bi0.5Sb1.5Te3 by electroless plating and annealing

With the capacity of energy conversion from heat to electricity directly, thermoelectric materials have been considered as an alternative solution to global energy crisis. In this work, Cu modified Bi_(0.5)Sb_(1.5)Te_3(BST)composites are prepared by a facile electroless plating Cu method, spark plasma sintering, and annealing. The annealed 0.22 wt.%Cu/BST has an enhanced peak Figure of Merit(z T) of ~ 0.71 at 573 K with high average z T of0.65 in the wide temperature range between 300 and 573 K. Due to the significant increase of electrical conductivity and low lattice thermal conductivity, the annealed 0.22 wt.%Cu/BST shifts peak z T to high temperature, and shows 492% enhancement than that of pristine BST with z T of 0.12 at 573 K. Through detailed structural characterization of the annealed 0.22 wt.%Cu/BST, we found that Cu can dope into BST matrix and further form Cu2 Te nanoprecipitates, dislocations, and massive grain boundaries, leading to a low lattice thermal conductivity of 0.30 Wm-1 K-1 in the annealed 0.22 wt.%Cu/BST. Such enhanced peak z T in high-temperature and high average z T in the wide temperature range shows that the electroless plating Cu method and annealing can improve the thermoelectric performance of commercial BST and expand the applicability of Bi_2Te_3 thermoelectric materials in the power generations.     

Mg-50wt.%Ti_(1-x)C(x=0.1,0.2,0.3,0.4)合金的贮氢性能研究

采用机械合金化方法制备Mg-50wt.%Ti1-xCx(x=0.1,0.2,0.3,0.4)贮氢合金.x-射线衍射(XRD)分析结果表明,合金主要由Mg、Ti、c以及二元合金相Ti2C0.06和Mg2C3组成,随着球磨时间增加,合金的非晶化程度提高.压强-成分-温度(Pcr)测试结果显示,Mg-50wt.%Ti1-xC(x=0.1,0.2,0.3,0.4)合金的贮氢量分别为2.96、2.95、2.76、2.6wt.%;随着碳含量的增加,样品吸氢量逐渐减少,放氢温度和平台压也随之下降;适当增加球磨时间可降低吸放氢温度.