(Ti-Cr)40V55Zr5储氢合金的热处理改性

研究了(Ti-Cr)10V55Zr5储氢合金在真空热处理(1473 K下保温2 h和6 h)改性前后的相结构及储氢性能.XRD及SEM分析表明,(Ti-Cr)40V55Zr5铸态合金由BCC结构的固溶体主相和ZrCr2基第二相组成;经过热处理后,合金的BCC主相的晶胞体积有所增大,除了BCC主相和ZrCr2基第二相外,还出现微量的富Ti第三相.储氢性能测试表明,热处理后(Ti-Cr)40V55Zr5合金的动力学性能和活化性能均得到改善,室温最大吸氢量略微降低,但P-C-T曲线放氢压力平台倾斜度降低,平台宽度稍有增大,80℃有效放氢量增大.研究表明,在1473 K下经2 h热处理改性的(Ti-Cr)40V55Zr5合金具有较好的综合性能,首次吸氢即可活化,室温吸氢量为401 ml·g-1,80℃有效放氢量达到240 ml·g-1.     

Ti0.096V0.864Fe0.04合金的储氢性能研究与物相分析

研究了Ti0.096V0.864Fe0.04合金的储氢性能、热力学特性及吸放氢物相变化.研究结果表明,该合金具有较好的吸放氢压力平台特性,合金的20℃最大吸氢量达到3.75%(质量分数),氢化物生成焓变△H°为-26.6kJ·(mol H2)-1,熵变△S°为-102.5J·(K·mol H2)-1.合金颗粒度、吸放氢循环次数对合金的吸氢速度都有较大影响.该合金具有较好的抗粉化能力,经过10次吸放氢循环后合金粉的平均粒径比吸氢前仅减小约1/5.XRD及SEM分析表明,合金未吸氢前是由单一的体心立方(BCC)结构的钒基固溶体相组成;4MPa下吸氢后生成大量面心立方(FCC)结构的Ti0.096V0.864Fe0.04H2.01和少量体心四方(BCT)结构的Ti0.096 V0.864 Fe0.04H0.81两种氢化物相;50℃下对0.001MPa放氢后,合金中除Ti0.096V00864Fe0.04基BCC固溶体相外,还存在Ti0.096V0.864Fe0.04H0.81氢化物相.     

V3TiNi0．56Alx贮氢合金充放电性能和吸放氢性能研究

用自蔓延高温合成法制备了钒基贮氢合金V3TiNi0．56Alx（x=0．1、0．3），用EDXRF、XRD等方法分析了合金的组织成分，并对合金进行了充放电性能和吸放氢性能测试。结果表明：随Al含量增加，合金的最大放电容量和吸氢量均减小，但循环稳定性提高；合金的放氢平台均在0．5MPa附近，随Al含量增加，平台宽度变窄、平台倾斜度增加。     

淬火对V40Ti26Cr26Fe8贮氢合金的影响

淬火工艺被广泛应用于钒基固溶体贮氢合金的热处理过程中,并被认为能够有效改善合金成份均匀性,提高合金的有效放氢量.考察了淬火对V40Ti26Cr26Fe8贮氢合金放氢PCT性能的影响.合金微观结构变化的分析表明,合金在退火态时存在C14 Laves相,淬火后Laves相固溶于BCC主相中,含量下降.成分分析表明,合金BCC主相淬火后Ti含量上升.与退火处理相比,合金放氢量和平台压在淬火后均出现下降.而合金在淬火过程中产生的缺陷及应力,导致了放氢平台倾斜,滞后增大且放氢量下降.     

热处理工艺对Ti-230合金薄板组织和性能的影响

研究了不同退火温度和退火时间对Ti-230钛合金板材显微组织和力学性能的影响.测试了不同退火工艺条件下合金薄板的强度和塑性.用金相显微镜和透射电镜观察了微观组织和析出相粒子Ti2Cu的分布.实验结果表明,随着退火温度从650℃升至790℃(保温30 min),合金板材的抗拉强度从541 MPa升到580 MPa,延伸率从27.5%降到26%.在给定790℃,保温时间分别为5,15,30 min条件下退火,其强度和延伸率变化不是十分明显.从OM和TEM对组织的观察得出,随着退火温度的升高,晶粒度明显增大,晶粒等轴化程度增加,析出的Ti2Cu粒子随退火温度的升高和保温时间的延长明显减少.采用790℃,30min退火工艺,其晶粒尺寸,Ti2Cu粒子的分布及Cu在基体中的固溶度可以达到良好的匹配,使合金获得最佳的力学性能.     

Ti-Cr-Mn-M(M=V、Fe、Ni、Cu)合金的储氢性能

为改善Ti(Cr-Mn)2 AB2型合金的储氢性能,采用A侧过化学计量和过渡金属部分替代Mn进行多元合金化,系统研究了Tix(Cr-Mn-M)2(x=1.0,1.1;M=V、Fe、Ni、Cu)合金的储氢性能.研究结果表明,V、Fe、Ni、Cu部分替代Mn进行多元合金化后,合金主相仍保持C14(MgZn2)型Laves相,合金晶胞体积增大.合金化元素部分替代Mn后合金的活化性能得到明显改善,合金吸放氢量增大,吸放氢压力滞后减小.除Fe使合金放氢平台压力有所升高外,其余合金化元素均使合金的吸放氢平衡压力有不同程度的降低,这是由于合金的晶胞体积增大所致.在所形成的合金中,以Ti1.1Cr1.2Mn0.5CuO0.3的综合性能最好,其室温下吸放氢量分别达到1.95%和1.72 9,6(质量分数).采用该合金与自制的轻质高压储氢容器(工作压力为40MPa)复合组成金属氢化物复合式高压储氢器,对其储氢密度的计算结果表明,当储氢合金的填充量(体积分数)达到0.20时,该复合式储氢器总的体积储氢密度将提高57%.     

V3TiNi0.56Alx贮氢合金充放电性能和吸放氢性能研究

用自蔓延高温合成法制备了钒基贮氢合金V3TiNi0.56Alx(x=0.1、0.3),用EDXRF、XRD等方法分析了合金的组织成分,并对合金进行了充放电性能和吸放氢性能测试.结果表明:随Al含量增加,合金的最大放电容量和吸氢量均减小,但循环稳定性提高;合金的放氢平台均在0.5MPa附近,随Al含量增加,平台宽度变窄、平台倾斜度增加.     

吸放氢处理对La_(0.6)Pr_(0.4)Fe_(11.4)Si_(1.6)B_(0.2)合金磁热效应的影响

使用工业纯度原材料制备出La0.6Pr0.4Fe11.4Si1.6B0.2合金,用XRD和VSM分析了合金的析出相、居里温度和磁热性能,研究了吸氢放氢处理对合金磁热性能的影响。结果表明:退火合金经0.13和0.2 MPa吸氢处理后居里温度分别达到320和321 K,吸氢压力高的样品放氢困难;经0.13 MPa吸氢样品在473 K放氢后居里温度降低到室温范围。放氢导致氢化物最大磁熵变降低和相对制冷能力RCP的提高。     

Co和Fe的添加对(TiZr)_(1.1)Cr_2合金结构和吸氢性能的调控

采用氩等离子体电弧熔炼(Ti_(0.9)Zr_(0.1))_(1.1)Cr_(2.0-x)M_x(M=Co、Fe,x=0~0.1)合金,并使用XRD、PCT、DSC研究了该系合金的相结构和吸放氢性能。研究结果表明,(Ti_(0.9)Zr_(0.1))_(1.1)Cr_(2.0-x)M_x(M=Co、Fe,x=0~0.1)合金结构为C14型Laves相,PCT测试表明,吸放氢的滞后效应较弱。使用少量Co、Fe分别替代(Ti0.9Zr0.1)1.1Cr2.0合金中部分Cr,减小了合金的晶胞体积,增大了合金的吸氢平台压。Co替代部分Cr在293~304K对合金的最大储氢量影响不明显,但是可逆储氢量略有降低,Fe替代部分Cr在293~304K对合金的最大储氢量影响不大,但是可逆储氢量增大。Co对合金中残余氢的放出温度影响不明显,Fe取代部分Cr使合金中残余氢的放氢温度从613~713K转变为653~733K。     

(Ti0.1V0.9)1-xFex(x=0～0.06)合金的相结构及储氢性能

系统研究了(Ti0.1V0.9)1-xFex(x=0、0.02、0.04、0.06)合金的相结构及其储氢性能.XRD及SEM分析表明,所有合金均由单一的体心立方(BCC)结构的钒基固溶体相组成;随着Fe含量的增加,合金的点阵常数呈线性递减,晶胞体积也随之逐渐降低.储氢性能测试表明,该系列合金的动力学性能均比较好,在10℃和4MPa初始氢压条件下,合金无需氢化孕育期就能吸氢.随着Fe含量从x=0增加至x=0.06,合金的活化性能得到改善;10℃最大吸氢量则从509.5ml/g逐渐降至424.8ml/g;而50℃有效放氢量先升后降,并在x=0.04时达到最高值255.6ml/g.在所研究的合金中,Ti0.096V0.864Fe0.04合金具有最佳的综合性能,经2次吸放氢循环即可活化,10℃最大吸氢量为494.5ml/g,50℃有效放氢量达到255.6ml/g.     

Effect of Preparation Technique on Microstructure and Hydrogen Storage Properties of LaNi_(3.8)Al_(1.0)Mn_(0.2) Alloys

La Ni3.8Al1.0Mn0.2 alloy was prepared by vacuum induction melting and melt-spinning.The effects of different preparation techniques of the as-cast,cast then annealed,as-spun and spun then annealed alloys on the microstructure and hydrogen storage properties were investigated.The results indicated that the non-Ca Cu5 phases in the alloy became tinier and more dispersive after annealing or melt-spinning compared to those of the as-cast one.But in the spun then annealed alloy,the non-Ca Cu5 phases disappeared and only a single-phase with Ca Cu5 type structure was found.For all the alloys,the cell volume was increased in an order of as-cast spun then annealed cast then annealed as-spun,and the change of plateau pressure showed the opposite trend with that of the cell volume.The plateau could be flattened after melt-spinning or annealing,and the spun then annealed alloy showed the minimum plateau slope.The absorption kinetics of the alloy was promoted after melt-spinning or annealing.It is suggested that the change in cell volume and compositional homogeneity resulting from different preparation techniques contribute to the difference of the hydrogen storage properties of the investigated alloys.     

退火温度对无镁La-Y-Ni系A2B7型合金相结构和电化学性能的影响

用XRD、SEM、EDS和电化学测试方法研究了退火温度对A₂B₇型La_0.33Y_0.67Ni_3.25Mn_0.15Al_0.1储氢合金微观组织和电化学性能的影响规律。结果表明, 合金铸态组织由2H-Ce₂Ni₇、3R-Gd₂Co₇、CaCu₅和3R-Ce₅Co₁₉型相组成; 随退火温度(850~950℃)升高, Ce₂Ni₇型主相丰度和晶胞体积逐渐增加, 至950℃退火后, CaCu₅和Gd₂Co₇型相基本消失, 主相Ce₂Ni₇型相丰度和晶胞体积均达到最大值; 退火温度≥950℃时, Ce₂Ni₇型和Ce₅Co₁₉型相丰度分别又有所减少和增加。950℃退火合金具有较低的放氢平台压(1.92~8.70 kPa)和较高的电化学放电容量(371 mAh/g), 经100次充放电循环后其容量保持率S₁₀₀达到89%。退火合金电极的HRD性能均得到不同程度的提高, 其中950℃退火合金具有最佳的大电流放电性能(HRD₉₀₀=83.4%)。氢在合金中的扩散是影响其高倍率放电性能的控制因素。     

机械合金化(Mg+Mg2 Ni)+TiO2合金的储氢性能

用机械合金化法合成了(Mg Mg2Ni) TiO2储氢合金,借助XRD分析了TiO2的加入对合金的物相结构的影响,SEM考察了合金的形貌.TiO2在合金的吸放氢过程中起到很好的催化作用,降低合金放氢温度并且提高合金储氢量,(Mg Mg2Ni) 10wt%TiO2合金在573K下的储氢量是5.84wt%.     

Effect of carbon addition on activation and hydrogen sorption characteristics of TiMn1.25Cr0.25 alloy

Effect of carbon addition on activation and hydrogen sorption characteristics of TiMn_1.25Cr_0.25 alloy is investigated. With increasing carbon contents, the lattice constants and the unit cell volume decrease. The activation of TiMn_1.25Cr_0.25 alloy becomes easier with the increasing carbon content. Auger electron spectroscopy (AES) results show that carbon addition does not reduce the thickness of oxide layer formed on the surface of TiMn_1.25Cr_0.25 alloy, but makes the Ti/Mn ratio of alloy top surface become closer to the bulk components, which probably is one of the reasons for the improvement of alloy activation performance. Pressure–composition–temperature (PCT) results present that carbon addition decreases hydrogen absorption capacity and increases the hydrogen absorption–desorption plateau pressure. In addition, the cycle-life of hydrogen absorption–desorption increases with increasing carbon concentration.     

An SANS Study of Decomposition Kinetics in Amorphous Cu_(12.5)Ni_(10)Zr_(41)Ti_(14)Be_(22.5)

Phase decomposition in amorphous Cu12.5Ni10Zr411Ti14Be22.5 alloy as annealed in the super-cooled liquid range was studied by applying small angle neutron scattering (SANS). As annealed between 600 K and 700 K, the alloy was observed to decompose into two new amorphous phases,with the second phase precipitates embedded in the matrix of the first. Long time annealing of the alloy results in crystallization in addition to evolution of the decomposed microstructure.The kinetic diagram of the decomposition and crystallization for this alloy is given. The second phase precipitates have several nanometers in size and occupy a quite low volume fraction. The decomposition of the supercooled liquid in overall temperature range exhibits the features of spinodal reaction.     

Microstructural evolution of Fe/Ti multilayers submitted to in situ thermal annealing

The Fe/Ti multilayers of nominal bilayer thickness of 4.0, 8.0 and 18.0 nm with alternating Fe and Ti sublayers thickness ratio of 1:1 were deposited by direct current magnetron sputtering on Si(100) substrates. The bilayer thickness of as-deposited Fe/Ti multilayers was measured as a modulation wavelength of 4.8, 8.5 and 19.0 nm, respectively, by small angle X-ray diffraction and cross-sectional transmission electron microscopy (XTEM). The three Fe/Ti multilayers were composed of pure metallic -Fe and -Ti according to wide angle X-ray diffraction and selected area diffraction. The Fe/Ti multilayers were in situ submitted to thermal vacuum annealing at the temperatures ranging from 523 K to 723 K for the annealing time of 3 h. With annealing at the lower temperature of 523 K, the intermetallic FeTi appeared in the Fe/Ti multilayers with small modulation wavelength of 4.8 nm. At 623 K, the intermetallic FeTi was formed with modulation wavelength of 8.5 nm. At the higher temperature of 723 K, the intermetallic FeTi was detected with modulation wavelength of 19.0 nm. The modulation wavelength of the Fe/Ti multilayers remained during the thermal annealing. The mixture of intermetallic FeTi and -Fe phase was observed in the extended Fe sublayer of the Fe/Ti multilayers annealed at 723 K by XTEM, correspondingly the remaining Ti sublayer was obtained as a thinned sublayer. Coexistence of the intermetallic FeTi, -Fe and -Ti phases indicated that the dynamic factors have control of the intermixing between the Fe and Ti sublayers in the Fe/Ti multilayers during the thermal annealing.     

不同处理状态V-60%（TiCrFeMn）的吸放氢特性

热处理工艺是改变金属材料微观组织结构和性能的常用手段,考察了退火和淬火以及淬火加低温回火对用FeV80中间合金代替纯钒制备的V-60%（TiCrFeMn）贮氢合金循环性能的影响。与退火处理相比,合金初始吸放氢量和平台压在淬火后均出现下降,合金的容量保持率提高。通过淬火,合金的成分均匀性虽然得到了改善,但合金放氢后会出现TiH2化合物相,TiH2化合物相所储存的氢无法在测试条件下放出,导致淬火后合金放氢量偏小。淬火后再低温回火,消除了一部分晶格微应力,合金的性能有一定改善。     

Recrystallization behaviour during annealing of cold-rolled Cu–5Fe–2Sn alloy

The recrystallization behaviour during annealing of cold-rolled Cu–5Fe–2Sn alloy was clarified in this paper. The effects of annealing temperature and time on the microstructure and properties of the Cu–5Fe–2Sn alloy were investigated. The equations of electrical conductivity and recrystallization kinetics during annealing were obtained with Martition's rule and Avrami empirical formula. The variations of recrystallization volume fraction and the growth of recrystallization grain for Cu–5Fe–2Sn alloy after 40% cold rolling were discussed. The calculated conductivity and volume fraction of recrystallization have a good match with experimental results. The variations of the properties of annealed Cu–5Fe–2Sn alloy are attributed to the growth rate of recrystallization phase and the size of recrystallization grains.     

Microstructure of Differently Annealed NanocrystallineFe_(72.7)Cu_1Nb_(1.8)Mo_2Si_(13)B_(9.5) Alloy

The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480℃ and 600℃ for 0.5 h. The experimental results show that the microstructure mainly consists of the nanoscale bcc α-Fe(Si) grains and the residual amorphous matrix phase. A trace paramagnetic phase was found for annealing about above 500℃. The volume fraction of cr-Fe(Si) grain increases with increasing annealing temperature, whereas the average size of grain is almost unchanged above 480℃ up to 580℃. The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperature.