快淬和退火对Fe_(83)Ga_(17)Ce_(0.8)合金结构和磁致伸缩性能的影响

采用电弧熔炼法制备了稀土Ce掺杂的Fe83Ga17Ce0.8铸态合金,然后对其进行快淬处理,获得Fe83Ga17Ce0.8快淬态合金,最后对Fe83Ga17Ce0.8快淬态合金在1 223K下进行退火热处理5h。用X射线衍射(XRD)、扫描电镜及能谱仪(SEM/EDS)和磁致伸缩测试方法研究了快淬和退火对合金结构和磁致伸缩性能的影响。结果表明,Fe83Ga17Ce0.8铸态合金由bcc结构的Fe(Ga)相和少量的CeFe2第二相组成。Fe83Ga17Ce0.8快淬态合金除了含有大量的Fe(Ga)相和少量的CeFe2相外,合金中还出现了非对称DO3结构的Fe3Ga相。Fe83Ga17Ce0.8快淬态合金经退火热处理后,合金中的CeFe2相转化为贫稀土Ce2Fe17相。在外磁场为557kA/m时,Fe83Ga17Ce0.8快淬态合金的磁致伸缩系数(3.82×10-4)明显大于铸态合金(3.56×10-4)和退火态合金(1.82×10-4)的磁致伸缩系数。     

Fe及Fe83Ga17和Fe83Ga17Pr0.3合金的微结构与磁致伸缩性能

本研究对比研究了Fe、Fe_(83)Ga_(17)及Fe_(83)Ga_(17)Pr_(0.3)磁致伸缩材料的微结构与磁致伸缩性能。采用真空非自耗电弧炉在氩气保护下熔炼制备了合金样品。采用X射线衍射仪(XRD)和光学显微镜(OM)分析观察了合金样品的晶体结构和显微组织。采用扫描电镜配合能谱仪(SEM/EDS)测定了稀土Pr元素在Fe_(83)Ga_(17)Pr_(0.3)合金中的分布。通过电阻应变法测量了合金的磁致伸缩性能。结果表明:Fe和Fe_(83)Ga_(17)合金均由单一的bcc结构A2相组成,而Fe_(83)Ga_(17)Pr_(0.3)合金由A2主相和少量的富稀土Pr相组成。稀土Pr掺杂使合金中的A2相沿〈100〉晶向择优取向。Fe及Fe_(83)Ga_(17)和Fe_(83)Ga_(17)Pr_(0.3)合金的微观组织分别呈现细长的条状晶、晶粒粗大的等轴晶和晶粒细小的柱状晶。Fe的磁致伸缩系数为负值,而Fe_(83)Ga_(17)和Fe_(83)Ga_(17)Pr_(0.3)合金的磁致伸缩系数均为正值,三种材料的磁致伸缩系数绝对值的排序为FeFe_(83)Ga_(17)Fe_(83)Ga_(17)Pr_(0.3)。     

元素替代、掺杂对Fe-Ga合金结构和磁致伸缩性能影响的研究进展

Fe-Ga合金是一种新型磁致伸缩材料,它的高强度、良好韧性、低场高磁致伸缩性能和低成本等优异特性使其具有广泛的商业应用。然而,实际制备的Fe-Ga合金的磁致伸缩数系数很小,提高Fe-Ga合金的磁致伸缩性能成为人们关注的课题。元素替代和掺杂是改善新型Fe-Ga磁致伸缩材料性能的一种有效方法。综述了近几十年来元素替代和掺杂对Fe-Ga磁致伸缩合金结构和性能的影响,并总结了各种元素替代和掺杂的研究进展。在此基础上,指出了元素替代和掺杂在改善Fe-Ga合金性能中存在的问题及今后的发展方向。     

第三组元(C、B)添加对Fe83Ga17合金相结构和磁致伸缩性能的影响

为了研究非平衡凝固条件下(Fe83Ga17)100-xMx(x=0、0.5、1、1.5;M=C、B)合金的相组成及其磁致伸缩性能,采用吹铸的方式制备了(Fe83Ga17)100-xMx,(x=0、0.5、1、1.5;M=C、B)合金,结果表明,合金保持了A2(bcc-Fe(Ga))相结构.C、B元素对合金微观组织产生了很大影响,C完全固溶于bcc-Fe中,B于晶界处大量富集,晶粒形状呈区域定向排列.添加C、B均对Fe83Ga17合金的磁致伸缩性能产生了抑制作用.添加C增大了弹性模量,当x=1时磁致伸缩值最大;添加B对合金组织产生了巨大影响,随着B含量的增加形成了明显的铸造织构,并且生成了富含Fe2B的相,x=1.5时磁致伸缩值最大.     

Fe-Ga-B合金室温塑性及轧制材料磁致伸缩性能

研究了0.5%(原子分数)B对Fe83 Ga17合金室温力学性能的影响及(Fe81 Ga19)99.5 B0.5轧制薄片磁致伸缩性能.结果表明,少量B添加提高了Fe-Ga合金的室温塑性,实现(Fe81 Ga19)99.5 B0.5合金的轧制成形.热处理对(Fe81 Ga19)99.5 B0.5合金薄片材料磁致伸缩性能有很大影响.在同一热处理制度条件下,磁致伸缩性能随变形量的增加而减小;对于变形量为93.5%的样品,同一热处理时间,样品磁致伸缩性能随热处理温度的升高而增加,同一热处理温度时,样品磁致伸缩性能都表现出先升高后降低的变化趋势,样品在1300℃保温2h后,磁致伸缩性能最好,达到1.65×10-4.热处理对(Fe81 Ga19)99.5 B0.5合金薄片材料磁致伸缩性能的影响归因于对样品织构的影响.具有{100}＜012＞织构样品的磁致伸缩性能最高,而{111}＜110＞和{111}＜112＞织构对应的磁致伸缩性能较低.     

〈110〉轴向取向Fe83Ga17合金中原子间作用与磁致伸缩的关系

采用定向凝固的方法制备出棒状〈110〉轴向取向多晶Fe83Ga17样品,Fe83Ga17合金样品经过淬火处理后,饱和磁致伸缩应变λs可以达到2.42×10-4。实验发现样品的磁致伸缩应变与合金中的短程序密切相关。淬火处理后样品的磁性Fe原子周围的原子占位发生了改变,合金部分有序。文中采用"原子对模型"(pairmodel),从能量最小原理出发,分析讨论了Fe Ga合金中原子对间的相互作用与磁致伸缩应变的关系。     

热处理对Fe81Ga19合金组织结构与磁致伸缩性能的影响

采用电弧熔炼法制备了Fe81Ga19合金多晶样品,研究了不同热处理工艺对合金组织结构及磁致伸缩性能的影响.样品经过700℃、800℃和900℃保温后采用空冷、炉冷和淬火3种冷却方式.结果显示,经过不同热处理后样品的微观组织均为单相bcc结构,而磁致应变从34×10-8到94×10-6不等;当热处理温度为800℃时,淬火处理后可获得较好的磁致伸缩性能(88×10-6),而热处理温度较高(900℃)时,采用炉冷的方式可获得较好的磁致伸缩性能(94×10-6).推测热处理方式和晶体取向对Fe81Ga19合金磁致伸缩性能有较重要的影响.     

Co元素添加对Fe83Ga17合金结构及磁性能的影响

制备目标成分为Fe83-xCoxGa17(x=0,0.5,1.5,2.5,3.5)系列的合金铸锭,研究了Co元素添加对该系列合金结构、磁致伸缩性能、磁性能及硬度的影响.实验结果表明,随着Fe-Ga合金中Co元素的增加,合金饱和磁致伸缩值先增加后降低,在x=1.5时,合金饱和磁致伸缩值最高,达到195·10-6,并且该成...     

Fe71.3 Ga28.7的结构调控与磁致伸缩性能研究

研究了区熔定向凝固速度与热处理制度对Fe_(71.3)Ga_(28.7)合金的显微组织、晶体结构与取向规律的影响。结果表明,区熔速度为72 mm/h时,得到的是A2相,而区熔速度为36 mm/h时,得到的是A2+D0_3相,并发现区熔速度较小时,会在合金棒中形成较强的η-型纤维织构;在680℃下淬火处理可以大大提高材料的磁致伸缩性能,不过在580℃下淬火处理或在705℃下炉冷处理时,会得到L1_2相,导致磁致伸缩系数为负值。     

新型磁致伸缩材料Fe-Ga合金的研究进展

Fe-Ga合金具有饱和磁场低、磁导率高、强度高、脆性小和温度特性好等优点,而且价格较低廉,使Fe-Ga合金在磁致伸缩器件领域具有广阔的应用前景.综述了该合金最近的研究工作,包括磁致伸缩机理、制备与热处理工艺以及提高和改善Fe-Ga合金性能的途径,并展望了今后Fe-Ga合金的发展.     

Magnetostriction and microstructure of the melt-spun Fe83Ga17 alloy ribbons

Fe₈₃Ga₁₇ alloy ribbons with four thicknesses were prepared by the melt-spun method. The measured results show that magnetostriction is related to the thickness of the ribbons, and its maximum value, −2100 ppm, has been obtained in the ribbon with a thickness of 75 μm. The results of the X-ray diffraction (XRD) and the differential scanning caloric (DSC) show that a phase with DO₃ structure emerges in those ribbons with the thicknesses of 45, 55 and 75 μm, and a phase transition of A2 + DO₃ → A2 occurred at 669°C for the ribbon with the thickness of 75 μm. The increase in the cooling rate can restrain the precipitation of the Ga-rich phase in the ribbon. It is considered that the giant magnetostriction of ribbons originates from the A2 + special DO₃ structure and shape magnetic anisotropy. Translated from Acta Metallurgica Sinica, 2006, 42(2): 177–180 [译自: 金属学报]     

Fe-Ga超磁致伸缩材料的性能和中子衍射分析

Fe-Ga合金具有较大的磁致伸缩应变λ,低的饱和磁化场.Fe83Ga17饱和磁致伸缩应变可以达到3.00×10-4.为了进一步验证不同相结构对合金磁致伸缩性能的影响,对样品进行中子衍射和差热分析,发现Fe83Ga17合金在700℃附近存在相结构变化,结构变化导致合金磁致伸缩系数的改变.     

热处理温度对La0.8Ce0.2(NiCoMnAl)5储氢合金结构与性能的影响

对快淬法制备的La0.8Ce0.2(NiCoMnAl)5储氢合金进行热处理,考察了热处理温度对合金的结构和性能的影响,并采用XRD、PCT、恒流充放电等测试方法对合金物相结构及性能进行表征。研究表明:热处理前后La0.8-Ce0.2(NiCoMnAl)5储氢合金均为CaCu5型相结构。热处理温度为950℃时,La0.8Ce0.2(NiCoMnAl)5合金储氢量为1.37%(质量分数),当放电电流密度为715mA/g时,合金放电比容量为307.68mAh/g,循环寿命超过300周,当放电电流密度为1200mA/g时,合金的HRD达到85.17%。     

Effect of thermal annealing on some electrical properties and optical band gap of vacuum evaporated Se65Ga30In5 thin films

Electrical properties and optical band gap of amorphous Se₆₅Ga₃₀In₅ thin films, which were thermally evaporated onto chemically cleaned glass substrates, have been studied before and after thermal annealing at temperatures above the glass transition temperature and below the crystallization temperature. The I-V characteristics, which were recorded in the temperature range (200-300 K), were obtained at different voltages and exhibit an ohmic and non-ohmic behavior at low (0-5 V) and high (5-18 V) voltages, respectively, for annealed and as-prepared films. Analysis of the experimental data in the high voltage range confirms the presence of space charge limited conduction (SCLC) for annealed and as-prepared films. The dependence of DC conductivity on temperature in the low voltage region shows two types of conduction channels: The first is in the range 270-300 K and the other at the lower temperature range (200-270 K). The conduction in the first region is due to thermally activated process, while in the other is due variable range hopping (VRH) of charge carriers in the band tails of the localized states. After annealing, the conductivity has been found to increase but the activation energy decreases. This is attributed to rupturing of Se-In weak bonds and formation of Se-Ga strong bonds. This process changes the concentration of defects in the films which in turn decreases the density of states N(E_F) as predicted by Mott's VRH model. Analysis of the absorption coefficient of annealed and as-prepared films, in the wavelength range 300-700 nm, reveals the presence of parabolic densities of states at the edges of both valence and conduction bands in the studied films. The optical band gap (E_g) was obtained through the use of Tauc's relation and is found to decrease with annealing temperature.     

Effect of doping with Co2O3, TiO2, Fe2O3, and Mn2O3 on the properties of Ce0.8Gd0.2O2?δ

The effects of Co, Fe, Mn, and Ti oxide additions on the sinterability and crystal-chemical, thermal, and electrical properties of Ce_0.8Gd_0.2O_2−δ have been studied. The results indicate that these oxides enhance the sinterability of the mixed oxide, regardless of whether they were introduced before or after synthesis. The most effective sintering aid is Co₂O₃. The lattice parameters of Ce_0.8Gd_0.2O_2−δ samples containing different metal oxide additions (1 mol %) are refined in space group Fm3m. The temperature-dependent thermal expansion data are used to determine the linear thermal expansion coefficients of the samples. Manganese oxide additions reduce the electrical conductivity of Ce_0.8Gd_0.2O_2−δ, whereas the other dopants increase it in the order Ti < Fe < Co. The activation energy for conduction increases in the order Co < Ti < Fe < Mn. Original Russian Text ? E.Yu. Pikalova, A.N. Demina, A.K. Demin, A.A. Murashkina, V.E. Sopemikov, N.O. Esina, 2007, published in Neorganicheskie Material, 2007, Vol. 43, No. 7, pp. 830–837.