ZrTi-V-Mn-Ni系贮氢合金的相结构与电化学性能研究*

优化合金组成,设计六种锆基AB2型贮氢合金材料。XRD分析表明,当0≤x≤0.5时,Zr1-xTix(NiCoMnV)2.1贮氢合金的主相都是Laves C15,但随Ti含量的增加,Laves C14相含量增多;当用V-Fe(85.6%)合金代替Zr0.6Ti0.4(NiCoMn-VFeCr)1.7中的V时,贮氢合金中Laves C14相的含量几乎可与Laves C15相当。电化学测试表明：Zr0.9Ti0.1(NiCoMnV)2.1贮氢电极的放电容量可达340mAh/g左右,但是随着Ti含量的逐渐增加,合金电极的放电容量降低很快。以适量的（V－Fe)合金取代Zr0.6Ti0.4(NiCoMnVFeCr)1.7合金中的V和Fe,发现合金电极的第一次放电容量就能达到200mAh/g左右,并且其容量稍高于含纯V的合金电极,容量可达315mAh/g左右。     

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%。     

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。     

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。     

贮氢合金Zr(Mn_(l-x)Ni_x)_2的相结构

贮氢合金Zr（Mnl－xNix）2（0.40≤x≤0．75）的多相Rietveld分析表明,它是以C15型Laves相ZrM2为主的多相体系、不同M／Zr原子比（M=Nix或Mnl-x）非Laves相合金的出现与丰度和整个合金成分配比中Ni／Zr原子比的变化一致,并与Ni－Zr相图中具有同样Ni／Zr原子比的金属间化合物有相同的晶型．x＝0．75,Zr7M10的丰度是38.57％;x＝0.55,C15Laves相的最大丰度达85.98％,电化学放电容量也达最大值242mAh／g;≥0.55,C14型Laves相丰度在2％左右;x＜0．55;C14型Laves相丰度随Mn取代量的增加而增加;x＝0．40,丰度是26.38％．取代量x的增减引起每个原子的平均价电子数的变化可以解释C15Laves相出现同丰度的变化     

合金V40Zr5Ti30Cr10Ni15Mox(x=0、2、4、6)的组织结构及电化学性能研究

研究了合金V40Zr5Ti30Cr10Ni15Mox(x=0、2、4和6)的相结构及电化学性能。结果表明,所有合金均由BCC结构的V基固溶体主相和C14型Laves相组成。电化学测试结果表明,合金的放电容量随着Mo含量的增加先增大后减小。在x=2时,合金具有最大的放电容量408.3mAh/g,20次循环后容量保持率为83.2%。合金的高倍率放电性能随着Mo含量和电流密度的增加而降低,x=2时,合金的倍率放电性能最好。     

Zr-Ti-Cr-Mn-V-Ni合金相结构和电化学性能

研究了非计量比合金Zr(Cr0.2Mn01V0.05Ni0.65)x(x=1.8～2.4)的相结构和电化学性质.结果发现,欠计量比时,随x变小,合金中C14型Laves相增多,第二相Zr7Ni10减少至消失,并出现了新相Zr9Ni11.而过计量比时,随x增加,合金中C14型Laves相和Zr7Ni10相都相应减少至消失,合金Zr(Cr0.2Mn0.1V005Ni0.65)24由C15型Laves单相组成.过计量比合金具有较好的活化性能,但非计量比合金的放电容量普遍低于计量比合金,而且非计量比对合金高倍率放电性能的提高影响不大.     

Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3储氢合金结构与电化学性能研究

采用XRD、FESEM-EDS、ICP及EIS等方法对Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3储氢合金的微观结构及电化学性能进行了研究.XRD分析结果表明Ti0.17Zr0.08V0.34Cu0.01 Cr0.1Ni0.3固溶体储氢合金由BCC结构的V基固溶体主相和少量的C14 Laves相组成.FESEM-EDS测试结果表明V基固溶体主相为树枝晶结构,C14 Laves相呈网格状围绕着树枝晶.电化学测试结果表明,Ti0.17Zr0.08V0.34 Cu0.01 Cr0.1Ni0.3氢化物电极在303～343K较宽的温度区间内具有良好放电容量,在343K时电化学容量高达316.5mAh/g;在303K时循环100周次后,其容量为278.2mAh/g,容量保持率为87.0%,表明氢化物电极具有较好的循环稳定性,但其高倍率放电性能较差.Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3氢化物电极的电化学阻抗谱表明,电极电化学反应的电荷转移电阻(RT)随温度的增加而显著降低,交换电流密度(I0)随温度的增加显著增加.ICP分析结果表明,V和Zr元素向KOH电解质中溶解严重,这可能是Ti0.17Zr0.08V0.34Cu0.01Cr0.1Ni0.3氢化物电极容量衰减的主要原因.     

合金V40Zr5Ti30Cr10Ni15Mox（x=0、2、4、6）的组织结构及电化学性能研究

研究了合金V40Zr5Ti30Cr10Ni15Mo x(x=0、2、4和6)的相结构及电化学性能。结果表明,所有合金均由BCC结构的V基固溶体主相和C14型Laves相组成。电化学测试结果表明,合金的放电容量随着Mo含量的增加先增大后减小。在x=2时,合金具有最大的放电容量408.3mAh/g,20次循环后容量保持率为83.2%。合金的高倍率放电性能随着Mo含量和电流密度的增加而降低,x=2时,合金的倍率放电性能最好。     

Zr1-xTix(Ni0.6Mn0.3V 0.1Cr0.05)2(x=0～0.5)Laves相储氢合金的电化学性能

本文研究Zr1-xTix(Ni0.6 Mn0.3V0.1Cr0.05)2(x=0,0.1,0.2,0.3,0.4,0.5)系Lav es相储氢电极合金的气态P-C-T性能、晶体结构及电化学性能.XRD分析表明,Ti合金化使 Zr基储氢合金主相从C15相转变为C14相.当x>0.2时,第二相Zr7Ni10相消失, 并出现TiNi相.Ti合金化使Zr基储氢合金中C15相和C14相的晶格常数线性递减.气态P-C-T 测试表明,Ti合金化从x=0增加至x=0.5时合金的吸放氢平台压力升高约10倍,但降低了储氢合金的最大储氢容量.电化学测试表明,Ti合金化有利于改善Zr基储氢合金的活化性能, 这与Ti在KOH溶液中易于溶解有关,但过高的Ti含量降低了合金电极的循环稳定性.Zr1 -xTix(Ni0.6Mn0.3V0.1Cr0.05)2合金的电化学容量和高倍率放电性能均随合金中Ti含量的增加先上升后下降,这与合金的相结构组成有很大关系 .     

Zr_(1-x)T_xMn_(0.6)Ni_(1.4)(T=Ti,V)合金的晶体结构和贮氢特性

本文研究了Zr_(1-x)T_xMn_(0.6)Ni_(1.4)(T=Ti,V;x=0,0.1,0.2,0.4,0.6)合金的晶体结构和贮氢特性。这种合金的晶体结构属于Laves相的六方结构,空间群为P6_3/mmc。用Ti和V原子替代部分Zr原子后,六方结构的晶格常数变小。六方结构晶格常数的变小致使合金的氢平衡分解压随着Ti和V原子含量的增加而升高。     

Role of late transition metals on pitting resistance of Zr-Ti-(Cu,Ni,Co)-Al bulk metallic glasses in 0.6 M NaCl aqueous solution

Four quanternary Zr-based bulk metallic glasses(BMGs)were selected,including the Zr_(46)Ti_2Cu_(45)Al_7,Zr_(61)Ti_2Cu_(25)Al_(12),Zr_(55)Ti_4Ni_(22)Al_(19)and Zr_(55)Ti_2Co_(28)Al_(15),due to their robust glass-forming ability and containing a single species of late transition metal(LTM)in compositions.Their pitting resistances in 0.6 M Na Cl aqueous solution were investigated to examine the role of LTM elements in the alloys,with electrochemical measurements,surface morphology observation and x-ray photoelectron spectrometry analysis.It is shown that in comparision with two Cu-bearing BMGs,Zr_(55)Ti_4Ni_(22)Al_(19)and Zr_(55)Ti_2Co_(28)Al_(15)BMGs exhibited significantly superior resistance to pitting.Zr_(61)Ti_2Cu_(25)Al_(12),Zr_(55)Ti_4Ni_(22)Al_(19)and Zr_(55)Ti_2Co_(28)Al_(15)BMGs manifested distinct passivation behaviour,because of the formation of surface passive film mainly comprising of Zr O_2,Ti O_2and Al_2O_3.However,no significant differences in the electrochemical resistive properties and thicknesses of passive films were found between Zr_(61)Ti_2Cu_(25)Al_(12)and Zr_(55)Ti_4Ni_(22)Al_(19)BMGs.Nevertheless,at the passive film/metal interface,copper enrichment took place in Zr_(61)Ti_2Cu_(25)Al_(12),whereas the nickel was slightly deficient at the interface in Zr_(55)Ti_4Ni_(22)Al_(19).During pitting propagation,selective dissolution of the zirconium,titanium and aluminum over the copper took place in Zr_(61)Ti_2Cu_(25)Al_(12),but it was not the case in Zr_(55)Ti_4Ni_(22)Al_(19).For the two Cu-bearing BMGs,reduction of passive base metal elements in composition resulted in local selective dissolution,even absence of the passivation.     

Dy替代M1对低钴贮氢合金组织和性能的影响

采用多元合金化及A侧稀土元素Dy取代M1的方法，制备出了多元低钴贮氢合金M1（1-x）DyxNi3．90 Co0．3 M0．4 Cu0．15 Fe0．1 Sno．1 Ti0．05（x=0．00、0．05、0．10、0．15），研究了加Dy对合金的微观结构、组织以及电化学性能的影响。XRD及EDS分析表明，Dy能很好融入主相晶格中，未单独形成第二相。电化学测试表明，适量Dy的加入能够提高低钴舍金的放电容量，以及合金的充放电循环稳定性。     

Cu粉和Ni粉添加剂对V20Ti30Cr50贮氢合金电化学性能的影响

采取手工混合和混合加烧结的方法,研究了Cu粉和Ni粉添加剂对V20Ti30Cr50贮氢合金电化学性能的影响.结果表明:烧结前,添加铜粉的V20Ti30Cr50合金的电极具有较高的放电容量,其最大放电容量为342.7mAh/g,但放电平台电压较低,仅为-0.4V(相对于Hg/HgO电极),而添加镍粉的合金电极的最大放电容量仅为73.4mAh/g,没有明显的放电平台;烧结后,添加铜粉的电极由于表面Cu4Ti3化合物的生成,电极的放电容量降低到30mAh/g,放电平台电压仍仅为-0.4V,而烧结的添加镍粉的电极合金与镍粉表面结合紧密,同时有TiNi第二相的生成,增加了合金电极表面的电催化活性,合金的放电平台电压提高到-0.8V,并且最大放电容量显著增加到209mAh/g.     

First-principles investigation of B2 partial disordered structure,martensitic transformation,elastic and magnetic properties of all-d-metal Ni-Mn-Ti Heusler alloys

In this work,the B2 partial disordered structure of the austenitic parent phase,martensitic transformation,elastic and magnetic properties of the Ni8 Mn4+xTi4-x(x=0,1 and 2) Heusler alloys have been systematically investigated by the first-principles calculations.The preferential atomic occupation of B2 structure is one Ti atom exchange with the nearest neighboring Mn atom from the view of lowest energy principle.This disordered exchange sites(Mn-Ti) and the excess Mn atoms occupying the Ti sites(MnTi)could reduce the nearest Mn-Mn distance,resulting in the anti ferromagnetic state in the austenitic and martensitic phases of the alloys.The total magnetic moment of the alloy decreases with the increasing Mn content;it is ascribed to the antiferromagnetic magnetic moments of the excess Mn atoms.When x=0,the alloy does not undergo martensitic transformation since the austenite has absolute phase stability.The martensitic transformation will occur during cooling process for x=1 or 2,owing to the energy difference between the austenite and the martensite could provide the driving force for the phase transformation.The elastic properties of the cubic austenitic phase for the Ni2 MnTi alloy is calculated,and the results reveal the reason why Ni-Mn-Ti alloy has excellent mechanical properties.The origin of martensitic transformation and magnetic properties was discussed based on the electronic density of states.     

La-Mg-Ni基(PuNi3型)贮氢合金的微观结构与电化学性能

用铸造及快淬工艺制备了La Mg Ni 系(PuNi3 型)贮氢合金La2Mg(Ni0.85 Co0.15)9Bx(x=0、0.1、0.2),分析测试了铸态及快淬态合金的微观结构与电化学性能,研究了硼及快淬工艺对合金微观结构及电化学性能的影响。结果表明,铸态合金具有多相结构,主相包括(La, Mg)Ni3 相和LiNi5 相,残余相为一定量的LaNi2 相和微量的Ni2B相,经快淬处理后Ni2B相消失,并且其它相的相对量随淬速的变化而变化。硼的加入提高了铸态及快淬态合金的循环稳定性,但使合金的容量下降。不含硼合金的容量随淬速的增加而单调减小,含硼合金的容量随淬速变化有一个极大值。合金的循环寿命随淬速的增加而增加,铸态及快淬态合金均有优良的活化性能。     

快速凝固MlNi4.0CO0.2Mn0.40Al0.30Cu0.10低Co贮氢合金的相结构和电化学性能

系统研究了单辊快淬快速凝固处理对低Co贮氢合金MlNi4.0Co0.2Mn0.40Al0.30Cu0.10的相结构和电化学性能的影响.XRD分析表明,铸态和快凝合金均为单相CaCu5型结构,但快凝合金的成分和结构均匀性得到明显改善,并具有较低的吸氢体积膨胀率(△V/V).电化学测试表明,快速凝固处理后合金的活化性能不变,循环稳定性得到显著改善,但其放电容量和高倍率放电性能有所降低.研究发现,快速凝固低Co合金循环稳定性能的改善主要归结于快凝合金具有较低的吸氢体积膨胀率和较好的成分均匀性,而快凝合金电极的电催化活性以及氢在合金中的扩散速率较铸态合金有所减小是导致其高倍率放电性能降低的主要原因.     

Anti-perovskite carbides and nitrides A_3BX: A new family of damage tolerant ceramics

Synergy effect of high stiffness and good damage tolerance is always the focus of the development of novel structural materials. Herein, a new strategy on the future damage tolerant material design is proposed to merge the strong covalent bonds into the easy shear deformed A_3B metallic box. This goal is realized by studying 126 A_3BX phases and establishing a database on their mechanical properties through highthroughput first principles calculations. The combination strategies of A_3B metallic box and XA_3 octahedra show intensive influences on the expected mechanical properties. The family includes 49 quasi-ductile compounds. Among them, four compounds(Ti_3AlN, Mn_3CuN, Ti_3TlN and Ni_3SnN) exhibit excellent damage tolerance and the other six compounds(Mn_3NiN, Mn_3GaC, Mn_3GaN, Mn_3SnC, Cr_3SnN, Co_3AlC) show both damage tolerance and high stiffness. Their competitive high temperature properties are demonstrated through the detailed investigation on the typical cases of Co_3Al C and Ti_3 Tl N. This study leads a novel direction for the design of the future quasi-ductile and high stiffness ceramics.