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.     

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.     

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...     

热处理对快淬Fe83Ga17Ce0.8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,获得快淬态Fe83Ga17Ce0.8合金,最后对快淬态Fe83Ga17Ce0.8合金在不同温度(850℃、950℃和1050℃)下进行退火处理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退火温度对合金结构和磁致伸缩性能的影响.结果表明,快淬态Fe83Ga17Ce0.88合金经退火处理后,合金中的CeFe2相转化为贫稀土Ce2Fe17相.随退火温度的升高,合金的磁致伸缩系数绝对值先减小后大幅度增大.退火温度为1050℃时,合金的磁致伸缩系数达最大(在外磁场为398 kA/m时,磁致伸缩系数为656×10-6).磁致伸缩系数的增大与该合金中形成较多的Ce2Fe17相以及合金中A2相沿[100]方向择优取向有关.     

添加元素Al对Tb0.3Dy0.7Fe1.95合金组织结构及性能的影响

研究了Tb0.3Dy0.7Fe1.95合金中添加少量Al替代Fe时,对合金晶体结构、显微组织、磁致伸缩系数影响.结果发现,添加Al没有改变合金的晶体结构,随着Al添加量的增加,晶体显微组织中的析出物增加;在一定的磁场强度下,磁致伸缩系数随Al添加量而变化,当磁场强度低于40kA/m时,磁致伸缩系数随Al添加量的变化曲线出现一峰值,当磁场强度高于40kA/m时,磁致伸缩系数随Al添加量的增加而降低.     

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.     

微量稀土元素掺杂引起Fe-Ga合金大磁致伸缩性能的研究进展

磁致伸缩材料是一类新型智能材料,在机器人、传感器和位移控制器等领域有重要的应用价值。与传统磁致伸缩材料和已商业化巨磁致伸缩材料相比,新型Fe-Ga磁致伸缩材料具有更易实用化的优良特性和应用前景,例如低磁场下应变高、力学性能好、对温度的依赖性低、价格低廉等,因而Fe-Ga合金成为凝聚态物理和材料科学领域的研究热点。早期关于Fe-Ga合金的研究主要集中在单晶Fe-Ga合金,但其制备工艺复杂、成本高,难以广泛应用。为拓宽Fe-Ga合金的应用范围,人们开始关注多晶Fe-Ga合金。然而,采用常规熔炼法制备的多晶Fe-Ga合金磁致伸缩系数很低,限制了其实际应用。因此,提高多晶Fe-Ga合金的磁致伸缩性能成为该类合金能广泛应用的关键。合金结构决定合金性能,合金结构又与合金成分和制备工艺密切相关。为提高多晶Fe-Ga合金磁致伸缩系数,研究者做了大量工作。近年来,具有特殊4f电子层结构的稀土元素因具有优异的磁学性质而引起人们的广泛关注。人们将微量稀土元素Tb、Dy、Ce、Y、Sm、Pr等掺杂到Fe-Ga合金中,发现Fe-Ga合金的磁致伸缩性能得到明显的改善。然而到目前为止,有关稀土掺杂Fe-Ga合金的磁致伸缩机制仍不一致。一些研究者认为磁致伸缩性能的改善是由于稀土掺杂导致Fe-Ga合金形成富稀土相,也有研究者认为主要是由于稀土掺杂使合金沿〈100〉择优取向。近年来一些研究者认为,大磁致伸缩主要源于稀土原子进入Fe-Ga合金的A2基体中引起的大四方畸变。但是稀土掺杂如何使Fe-Ga合金中A2基体产生大四方畸变以及掺杂稀土与A2基体中四方纳米异质结构modified DO3相是如何作用的,这些问题仍不清楚。本文首先分析了人们选择稀土元素掺杂Fe-Ga合金的原因;然后分析了稀土元素掺杂对Fe-Ga合金性能的影响;最后详细综述了稀土元素掺杂引起Fe-Ga合金大磁致伸缩性能的理论机制,同时展望了该类合金未来的发展方向。     

Pr0.15Tb0.30Dy0.55Fe1.85-xNix合金的磁性和磁致伸缩研究

用电弧炉熔炼得到Pr0.15Tb0.30 Dy0.55Fe1.85-xNix系列合金.通过X射线对合金进行结构分析,并拟合衍射峰得到晶格常数;样品的居里温度采用交流磁化率测量系统得到;磁化强度、磁致伸缩分别由振动样品磁强计和标准应变测试系统在室温下测量得到.实验表明所有的样品均呈现MgCu2型Laves相结构;随着Ni替代量的增加,样品晶格常数、居里温度和磁化强度呈现下降趋势;磁致伸缩系数亦表现为下降趋势,但在x=0.2、0.3处有所反弹,且x=0.3时样品在低场下的磁致伸缩值略高于无Ni替代的样品.     

聚合物基磁致伸缩复合材料的研究进展

聚合物基磁致伸缩复合材料是一种新型的功能材料.综述了近年来有关聚合物基磁致伸缩复合材料的研究情况,介绍了磁致伸缩机理、传统的磁致伸缩材料的特点,以及聚合物基磁致伸缩复合材料的产生,总结了聚合物基磁致伸缩复合材料的性能影响因素、制备工艺和应用情况,提出了今后聚合物基磁致伸缩复合材料的研究方向.     

热处理工艺对HOVF制备磁致伸缩涂层组织及性能的影响

采用超音速火焰喷涂方法制备Fe-Ga磁致伸缩涂层作为磁致伸缩导波传感器的敏感性元件.研究300～700℃不同热处理温度对Fe-Ga涂层质量的影响,采用SEM、XRD和磁致伸缩测试仪研究热处理过程中涂层的微观组织和性能变化.结果表明,退火过程中,Fe-Ga涂层保持单一的A2相结构,300～600℃温度范围内颗粒中的变形晶...     

The magnetoelectric effect in Ni-Fe alloy/ZnO nanorod array composites

Ni-Fe alloy/ZnO nanorod composites were fabricated and the magnetoelectric effect was demonstrated. The ZnO and Ni-Fe alloy serve as the piezoelectric phase and the magnetostrictive phase in the nanocomposite, respectively. Since the nanorod structure possesses the inherent nature of a large surface-to-volume ratio, it greatly enhances the interplay between the piezoelectric and magnetostrictive coupling. Besides, the substrate clamping effect can be avoided. Our newly devised composite therefore provides a different species for magnetoelectric applications. It is interesting that the magnetoelectric voltage coefficient determined by the direct measurement method can reach a value as high as 0.48?mV?cm(-1)?Oe(-1).     

Influence of nickel addition on magnetic and electro-mechanical behaviour of permalloys

Magnetic and electro-mechanical investigations have been carried out in two Ni-Fe permalloys under hydrogen atmosphere by varying annealing temperature. These alloys have been characterized for various magnetic parameters like peak permeability, coercivity and core loss under changed annealing profile conditions. The magnetic properties of Ni-rich (Ni ∼ 82%) alloy at 100 Hz were found to be better than the low Ni (Ni ∼47%) alloy. The alloys were tested for watch movement and found that the battery life of the watch movement improved by 38% using Ni-rich permalloy.     

脱合金化制备纳米多孔Ni-Fe合金及其电催化性能

采用真空熔炼与固溶相结合的方法获得原子分数为Ni_30-xFe_xMn₇₀(x=0,10,20)的前驱体合金,通过脱合金化方法制备纳米多孔Ni及Ni-Fe合金,采用X射线衍射(XRD)、扫描电子显微镜(SEM)分析合金相组成和微观结构,运用线性扫描伏安法、交流阻抗、方波电位法及计时电位法研究电极的析氢电催化性能。结果表明:加入Fe获得了片状结构的纳米多孔Ni-Fe合金,提高了纳米多孔Ni的表面积,且Fe与Ni产生协同效应,能够有效提高合金的析氢电催化活性。当Fe含量为10%(原子分数)时,脱合金化得到的纳米多孔Ni-Fe合金表面积最大,析氢电催化性能最好,在0.1A/cm^2电流密度下,析氢过电位仅56mV,经10h连续电解,表现出良好的电催化活性和电化学稳定性。     

Low-stress permalloy for magnetic MEMS switches

The residual stress in the electroplated magnetic films is an important factor that limits the functionality of many micromagnetic devices. We have investigated the stress in electroplated Ni-Fe alloy for MEMS as a function of bath concentration, utilizing the wafer-bending method. Our investigation demonstrated that a low-concentration plating solution decreases the residual stress in the electrodeposits, and the stress is further decreased by increasing the saccharin additive content. We obtained the low-stress Permalloy Ni/sub 81/Fe/sub 19/ in our experimental conditions. We fabricated a bistable electromagnetic RF MEMS switch with deformation-free cantilever beam using the electroplated Permalloy.     

Magnetostrictive materials and applications

The dynamic magnetostrictive properties of materials and their applications will be reviewed. The order of presentation is to first discuss the various dynamic magnetostriction contentsK(defined by Smith), λ and γ (defined by Butterworth and Smith), and Γ (defined by the present author). Next, the application of the magnetic domain theory to dynamic magnetostriction will be presented. The ΔE-effect, a useful material criterion, will then be examined. Experimental results of the electromechanical coupling factor at an optimum bias are then shown. The second section of the paper will present the magnetostrictive characteristics of Ni, Ni-Fe alloys, Fe-Al alloys, other metals, cobalt rondel, and the ferrites. Much of the emphasis will be placed on the effects of cold reduction, hysteresis phenomena, and the effects of oxide films. Empirical formulas which describe these properties are presented. Large amplitude ferrite vibrators are described. The third part of the study is devoted to a phenomological method of predicting the magnetostrictive characteristics of polycrystalline metals. Experimental data for iron which agrees with the model is presented. The effect of anisotropic grain growth is discussed in terms of the model. The last section is devoted to the mechanical power limitations of magnetostrictive vibrators both from the theoretical and the experimental points of view.     

Surface structures of synthetic diamonds

Diamond crystals of about 2 mm in size were grown by the temperature gradient method using Ni, Ni-Fe alloy and Fe as solvent metals. Several characteristic patterns were seen on the surfaces of the grown diamonds and were found to correspond to the texture of the quenched solvent metals. A vague vein-like pattern appeared when Ni was used. The surface patterns became finer with the increase of the content of Fe in Ni-Fe alloy, and when 70 wt% Fe-30 wt% Ni alloy was used, very fine dendritic patterns were seen on all of the faces of diamond in accordance with the symmetries of the lattice. The patterns are formed by the precipitation of carbon atoms in the space of the dendrites of the solvent metals during the quenching process. Lamellar patterns and etch pits were seen when Fe was used. The patterns are formed when Fe dissolves the diamond surfaces to produce Fe₃C during the quenching process.     

Annealing of cylindrical Ni-Fe films

The effect of annealing on the microstructure of cylindrical electrodeposited 81-percent Ni, 19-percent Fe films was studied with the electron microscope. The films were deposited onto 5-mil Be-Cu wires having either Au or Cu intermediate layers. The annealing was performed on both free-standing films and on films still attached to the substrate. The initial change in the free-standing films was a rapid recrystallization. After the whole film had recrystallized, normal grain growth was observed. There is evidence that the driving force for the annealing is provided by stresses present in the films. Films annealed while attached to a Au-Be-Cu substrate did not exhibit recrystallization or grain growth, and the electron microscope studies showed that the Ni-Fe grains were pinned by Be-Au which diffuses into the grain boundaries but does not alloy with the Ni-Fe. The films which were annealed while attached to a Cu-Be-Cu substrate behaved essentially like free-standing films. Electron beam microanalysis and electron diffraction studies revealed that Be-Cu diffuses into the Ni-Fe grain boundaries and then alloys with the Ni-Fe. Recrystallization of the alloy can then take place freely.     

The preparation and properties of electrodeposited permalloy films on substrates of evaporated permalloy

The technology of production and some of the properties of isotropic magnetic Ni 80%-Fe 20% films are described. These films were obtained by permalloy electrodeposition onto glass substrates previously coated with vacuum-deposited thin films of Ni-Fe alloy. The change in the magnetoresistance of the films as a function of thickness has been investigated and is discussed, taking into account the influence of the film composition. The results are compared with those previously reported for evaporated films. The dependence of coercive force on film thickness is given. An increase in the crystallite size of the electro-deposited films with respect to the vacuum-deposited substrate has been found.     

Cavitation Erosion Behavior of as-Welded Cu12Mn8Al3Fe2Ni Alloy

Cavitation erosion behavior of as-welded Cu12Mn8Al3Fe2Ni alloy in 3.5% NaCl aqueous solution was studied bymagnetostrictive vibratory device for cavitation erosion. The results show that the cavitation erosion resistance ofthe as-welded Cu12Mn8Al3Fe2Ni alloy is much more superior to that of the as-cast one. The cumulative mass lossand the mass loss rate of the as-welded Cu12Mn8Al3Fe2Ni alloy are almost 1/4 that of the as-cast one. SEM analysisof eroded specimens reveals that the as-cast Cu12Mn8Al3Fe2Ni alloy is attacked more severely than the as-weldedone. Microcracks causing cavitation damage initiate at the phase boundaries.     

镍-铁合金镀液的转化

介绍了用高锰酸钾处理转化镍-铁合金镀液为亮镍镀液的工艺过程,结果表明,转化后的镀液澄清,试镀工件质量良好,方法简单易行,具有良好的经济性和可行性.