非晶态物理与软磁材料的产业化

由于非晶态材料具有独特的结构和优异的性能,其发现和发展对相关传统材料及其应用领域产生了巨大的冲击和深远的影响.从1960年首次发现非晶合金至今已有40余年,基础研究和应用开发均取得长足进展,特别是作为软磁材料的非晶合金带材已经实现了产业化,并获得了广泛应用.文章综述了非晶态物理方面的一些基本问题,以及非晶软磁合金的发展历程和产业化现状.     

金属多层膜间固相反应非晶化的机理

通过固相反应将晶态的金属转变为非晶态合金是近年来人们发现的一种新的制备北晶态合金的方法，这种方法原则上完全不受以往限制人们获得大块非晶态合金的因素的约束，因而给我们开发适合于大规模工业应用的非晶态合金生产工艺开辟了新的途径．目前，人们对固相反应非晶化机理的研究可以分为两个方面，一是固相反应的反应驱动力；二是固相反应的动力学过程．本文着重就金属多层膜间固相反应非晶化机理的实验和理论研究作了一些介绍．     

非晶态合金与氢相互作用的研究进展

非晶态合金在力学性能、耐磨耐蚀性、磁性等方面比传统晶态合金具有显著优势,是一类有优良应用前景的新型结构与功能材料.非晶态合金与氢相互作用可以产生很多有趣的物理化学现象和应用.本文从物理基础和材料应用两个方面评述非晶态合金和氢相互作用的研究进展,在物理基础研究方面,从氢在非晶态合金中的存在状态出发,讨论氢在非晶态合金中的溶解、分布、占位和扩散等相关物理问题,进而分析氢对非晶态合金的热稳定性、磁性、内耗、氢脆等的影响.在材料应用研究方面,对非晶态储氢合金、非晶态合金氢功能膜、吸氢改善非晶态合金的塑性和玻璃形成能力、氢致非晶化、利用非晶态合金制备纳米储氢材料等方面的研究进展进行评述.最后总结并展望有关非晶态合金与氢相互作用的研究和应用.     

获得非晶态块状合金的新方法—固态反应及机械合金化

本文简介了近年来发展的两种获得块状非晶态合金的方法，即固态反应法及机械合金化方法，包括工艺过程，基本特性及与液态快淬法非晶化的比较等．     

非晶态磁性合金的研究与应用

本文简要地介绍了国内外非晶态合金近年来的生产情况，介绍了非晶态合金在电力变压器方面应用的现状及其意义，列举了非晶态台金在电子变压器方面应用的实例，介绍了一些与非晶态磁性合金的应用密切相关的技术进展和研究工作，评述了非晶态磁性合金的发展前景．     

非晶态合金薄带制取装置

应用急冷技术制成非晶态合金薄带的研究工作，目前在国内发展较快。随着产品需求量的增加，新工艺、装备、技术研究必须由实验室走向工业生产。本文介绍50kg级非晶薄带制取装置。该设备设计结构独特，技术先进，是目前我国容易较大、功能较全的非晶薄带制取装置之一。在该装置上已获得Fe基和FeNi基非晶合金宽带，产品性能良好。     

几种铁基非晶合金激波诱导晶化中的若干奇异物理效应研究

应用x射线衍射、透射电子显微镜和差示扫描量热实验技术，研究了FeCuNbBSi，FeBSi，FeMoBSi几种铁基非晶合金的激波诱导晶化.研究结果表明：非晶态合金激波诱导晶化中存在若干应用传统长程扩散相变理论难以解释的奇异物理效应.用非晶态合金激波流化晶化可以很好地解释激波诱导非晶晶化中的各种奇异物理效应. 关键词： 激波晶化 非晶态合金 激波流化 流体扩散     

新型非晶态金属的制备,应用及研究展望

首先对非晶态材料的电、磁、机械、化学等优异特性作了介绍；在第二部分着重介绍非晶态材料的制作方法，用这些方法可以让许多不同基的合金在很宽的成分范围内形成不同形伏的非晶态材料；对近期非晶态材料的应用研究及所取得的许多新成果方面在第三部分作了介绍；最后对非晶态村料的未来进行了简单的评价．     

铁基非晶的低频脉冲磁场处理效应

对非晶合金Fe₇₈ Si₉ B₁₃进行了低频脉冲磁场处理，用穆斯堡尔谱学、透射电 镜等方法观察处理试样的微观结构变化.研究发现，当脉冲频率20—25Hz,磁场16—32kA/m,作用时间≤2min，合金发生了纳米晶化，纳米相岐睩e(Si)晶粒尺寸为10nm. 而且，在低频脉冲磁场处理过程中，非晶试样的温升≤20℃. 关键词： 非晶态合金 脉冲磁场处理 纳米晶化     

具有宽过冷液相区的Fe62 Co8-x(Cr,Mo)xNb4 Zr6 B2非晶态合金的热稳定性与磁性

根据制备块状非晶态合金的三条经验准则,选择了成分为Fe62Co8-xCrxNb4Zr6B20和Fe62Co8-xMoxNb4Zr6B20(x=0,2,4)的合金系.利用单辊急冷法制备出厚为30μm宽为5mm左右的条带,并用差热分析、X射线衍射以及Faraday磁天平、静态磁性测量仪等研究了合金的热稳定性、非晶结构和磁性能.发现含2at%Cr的Fe62Co6Co6Nb4Zr20B20非晶态合金的过冷液相区ΔTx最宽,达到85K,但是合金系的饱和比磁化强度σs随Cr或Mo含量的增加而急剧下降.合金系经973K真空退火900s后,由于晶化相α-Fe等晶相析出,使得各合金的σx和Hc都迅速升高.     

The structure and magnetic properties of amorphous magnetic thin films

A review of the structural and magnetic properties of amorphous ferromagnetic and ferrimagnetic thin films is presented. An attempt is made to report structural information on atomic and microstructural scales, and to stress its relevance to the magnetic properties of these materials. The more obvious microstructural features of deposited films are not present in the other important type of amorphous magnetic material prepared by rapid quenching from the melt, and present opportunities for differences in structure dependent magnetic properties. In the main, three classes of amorphous magnetic films are considered. Ferromagnetic transition metal (TM) films which are metastable only at temperatures well below room temperature are discussed. Their importance lies in the fact that they clearly represent the most fundamental amorphous phase. Ferromagnetic transition metal-metalloid (TM-Me) alloys have potential applications as magnetically soft materials. These alloys are, perhaps, the most studied amorphous magnetic materials both in deposited thin film and rapidly quenched ribbon forms. Finally, amorphous rare earth-transition metal (RE-TM) films are reviewed. They exhibit a wide variety of magnetic properties encompassing both extremely low and very high coercivities and also perpendicular magnetic anisotropy. The possible application of these materials in various types of device has encouraged much detailed research into their magnetic properties. This has highlighted the importance of preparation conditions and microstructure in defining their properties.     

The role of material microstructure in the magnetic behavior of amorphous and polycrystalline Co<Subscript>x</Subscript>Si<Subscript>1-x</Subscript> lines

The role of material microstructure in the magnetic anisotropy of real nanostructures has been studied by the comparison of the magnetic behavior of arrays of amorphous and polycrystalline Co_xSi_1-x lines. From the experimental measurements of angular dependences of remanences parallel and perpendicular to the applied field we determine the angular dispersion of effective local easy axis of anisotropy. We have proved that amorphous lines have a dispersion of effective anisotropy axis much smaller than the polycrystalline samples. As a consequence, amorphous lines have a better defined magnetic behaviour, pointing the interest of the fabrication of nanostructures made of amorphous materials.     

铀基非晶合金的发展现状

铀基非晶合金是非晶家族中的特殊成员,受限于铀元素的高活性与放射性特点,目前这类非晶材料的研究极不充分.本文结合非晶合金的最新发展动态简要介绍了铀基非晶发展历史,较系统地总结了本团队的最新铀基非晶研究工作:首先较详细地介绍了新型铀基非晶的制备技术、成分体系、形成规律与晶化行为,澄清了其形成机制与热稳定性;结合高分辨电镜分析展示了其微观结构特点;采用纳米压痕技术揭示了这类非晶的微纳力学性能;利用电化学测试方法评估了其耐腐蚀性能.这些结果丰富了非晶材料的内涵,有助于深化对非晶物理基础科学问题的理解,并推动新型铀合金材料的发展,为这种材料的潜在工程应用奠定了基础.     

铁基软磁非晶/纳米晶合金研究进展及应用前景

非晶合金通常是将熔融的金属快速冷却、通过抑制结晶而获得的原子呈长程无序排列的金属材料.由于具有这种特殊结构,铁基软磁非晶合金具有各向同性特征、很小的结构关联尺寸和磁各向异性常数,因而具有很小的矫顽力H_c,但可和晶态材料一样具有高的饱和磁感强度B_s.优异的软磁性能促进了铁基软磁非晶合金的应用研究.目前,铁基软磁非晶/纳米晶合金带材已实现大规模工业化生产和应用,成为重要的高性能软磁材料.本文回顾了软磁非晶合金的发现和发展历程,结合成分、结构、工艺对铁基非晶/纳米晶合金软磁性能的影响,介绍了相关基础研究成果和工艺技术进步对铁基软磁非晶/纳米晶合金研发和工业化应用的重要贡献.并根据结构、性能特征将铁基软磁非晶合金研发与应用分为三个阶段,指出了目前铁基软磁非晶合金研发与应用中面临的挑战和发展方向.     

Composition dependence of microstructure,magnetic and microwave properties in ball-milled FeSiB nanocrystalline flakes

The soft magnetic nanocrystalline/amorphous FeSiB flakes were fabricated by the ball-milling method and evaluations were made of the composition, microstructure, magnetic and microwave properties in the milling process. An investigation of the relationship between microstructure and magnetic/microwave properties showed that the electromagnetic characteristics were attributed to the changes of nanograin size, crystal and amorphous content corresponding to the composition variation. The replacing of Fe atoms by Si in α-Fe crystal caused the decrease of grain size, saturation magnetization and coercivity, while B content devoted to amorphous phase and decreased the permittivity. Consequently, it was observed that the optimum composition for microwave performance is Fe₈₂Si₅B₁₃.     

Advances in amorphous and nanocrystalline materials

A new amorphous alloy has been recently introduced which shows a saturation magnetic induction B_s of 1.64 T which is compared with B_s=1.57 T for a currently available Fe-based amorphous alloy and decreased magnetic losses. Such a combination is rare but can be explained in terms of induced magnetic anisotropy being reduced by the alloy's chemistry and its heat treatment. It has been found that the region of magnetization rotation in the new alloy is considerably narrowed, resulting in reduced exciting power in the magnetic devices utilizing the material. Efforts to increase B_s also have been made for nanocrystalline alloys. For example, a nanocrystalline alloy having a composition of Fe_80.5Cu_1.5Si₄B₁₄ shows B_s exceeding 1.8 T. The iron loss at 50 Hz and at 1.6 T induction in a toroidal core of this material is 0.46 W/kg which is 2/3 that of a grain-oriented silicon steel. At 20 kHz/0.2 T excitation, the iron loss is about 60% of that in an Fe-based amorphous alloy which is widely used in power electronics. Another example is a Fe₈₅Si₂B₈P₄Cu₁ nanocrystalline alloy with a B_s of 1.8 T, which is reported to exhibit a magnetic core loss of about 0.2 W/kg at 50 Hz and at 1.5 T induction. This article is a review of these new developments and their impacts on energy efficient magnetic devices.     

Magnetic properties of amorphous alloys

The magnetic properties of existing amorphous iron based materials, i.e., Fe--metalloid, Fe--early transition metals and Fe--rare earth alloys, are briefly discussed for some representative alloys. The spin orientation of amorphous Fe--metalloid alloys has been determined by the angular dependence of hyperfine interactions. It is shown that in iron--early transition metals ferromagnetic order is not long-ranged, but determined by magnetic clusters. The magnetic hyperfine field distributions of Fe-rich iron--early transition metals consist of a high and a low field tail. The magnetic structure has been investigated for two representative Fe--RE (RE = Er, Ce) amorphous alloys. For the first time, the magnetic coupling phenomenon in amorphous/crystalline multilayers has been discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

The physics of amorphous and nanocrystalline hard magnetic materials

The magnetic properties of amorphous and nanocrystalline hard magnetic materials are summarized. The reduction of the “effective” anisotropy field due to exchange coupling in nanocrystalline materials is demonstrated. This leads experimentally as well as theoretically to a remanence enhancement and to a reduced coercivity. Also the domain structure shows the effect of exchange coupling. Nd–Fe–Al is taken as an example of a new “amorphous” hard magnetic material. For magnetostrictive materials the possibility of reducing the anisotropy in nanocrystalline samples without loosening the high magnetostriction is discussed.     

磁性材料新近进展

磁性材料是应用广泛、品种繁多的一类重要的功能材料，20世纪90年代以后发展十分迅速．稀土-3d过渡族磁性合金材料，如稀土水磁、巨磁致收缩材料、巨磁热效应材料，磁光效应材料等，以及非晶，纳米微晶磁性材料相继问世．1988年巨磁电阻效应的发现已获广泛应用，如读出磁头、传感器以及磁随机存储器等，并发展成为自旋电子学的新学科．文章简要介绍了近年来磁性材料的一些新进展。     

Applied research on amorphous magnetic materials

Amorphous magnetic materials are increasingly becoming an industrial reality, with a variety of applications to electronics and electrical engineering. Many research lines are in progress for what concerns the production techniques, the understanding of the structure and properties of amorphous ribbons, the optimization and extension of their applications. The fast quenching methods used to obtain amorphous materials will first be reviewed, also describing an experimental apparatus set up by the authors for laboratory investigations of rapid solidification processes. Becauses of the non equilibrium structure of amorphous metallic alloys, various relaxation effects are expected to occur, which may partially limit the use of these materials. Studies of these relaxation phenomena, performed by different methods, including Mossbauer spectroscopy will also be reviewed, showing their importance in better understanding the amorphous structure. Finally much attention will be devoted to actual applications of amorphous magnetic materials. Emphasis will be placed on the prospective applications of amorphous ribbons characterized by very low power losses to magnetic cores of distribution transformers, pointing to the possible advantages, but also to the technical problems involved with the substitution of crystalline laminations with the new amorphous materials.