铁钴钒软磁合金损耗谱的分形结构

研究了铁钴钒软磁合金的铁芯损耗，发现铁芯损耗谱具有分形结构，讨论了带材厚度和磁感应强度对分形维数Ｄｆ的影响。     

铁钴钒软磁合金损耗谱的分形结构

研究了铁钴钒软磁合金的铁芯损耗，发现铁芯损耗谱具有分形结构。讨论了带材厚度和磁感应强度对分形维数Ｄｆ的影响。     

矩形回线软磁合金损耗谱的分形性质

研究了矩形回线软磁合金的磁性，发现铁芯损耗谱具有分形结构，研究了热处理条件及带厚对分形维数Ｄ的影响。     

高导磁非晶软磁合金磁退火效应的初步研究

本文介绍高导磁Fe-Co-Si-B和Fe-Ni-Co-Si-B非晶软磁合佥的磁场热处理效应,并将其效应与晶态Fe-Ni系软磁合金的磁场热处理效应相比较,探讨非晶软磁合金磁场热处理效应的特殊性。我们做了两种磁场退火试验：即纵向磁场热处理和横向磁场热处理。在做此实验前首先测定了它们的比重(d),居里温度(Tc),电阻率(ρ)和结晶化温度(Tcr)等有关性能参数。纵向磁退火选了5个温度：300℃,330℃,375℃,400℃及420℃, (此合金Tcr约480℃,Tc约420℃)。横向磁退火只选用了1个温度(330℃)。磁退火前后测试它们的交、直流磁特性,性能测试采用环样,交流磁性测试时,样品是用绝缘纸绝缘的。根据试验结果,并将其与晶态Fe-Ni系软磁合金比较,我们总结了以下几点：1．这两种高导磁非晶软磁合金经磁退火后具有与晶态软磁合金类似的效果：即纵向磁退火后μmax成倍提高,Hc大大下降,矩形比Br／Bs明显增加,横向磁退火后磁导率在一定磁场范围内恒定。这说明磁场热处理同样可使非晶软磁合金产生明显的感生磁各向异性(Ku),它可能是来源于原子的方向有序或空位的方向有序。2．从磁退火前后性能提高的幅度来看,本试验所用的两种非晶软磁的磁场热处理效应不如晶态软磁合金的效应大。为此,我们测定了非晶磁退火后的Ku,其值约为1．2×103erg／cm3,它比晶态1J65的Ku小一倍多,这可能是由于非晶软磁的磁退火温度受到Tcr的限制而不能很高,以致影响原子扩散过程,方向有序的形成也不很理想。再者我们发现Fe-Co-Si-B非晶软磁经退火处理后磁导率下降,这可能是在退火中消除了原有的由制造带来的应力各向异性,这样在经磁退火的过程中,虽然由于磁场的作用产生了方向有序使性能提高,同时又由于消除了应力的备向异性而使性能下降,综合作用的结果表现出经磁退火后性能的提高幅度不如晶态软磁的大。因为晶态软磁合金在遇火时性能也是提高的,经磁退火性能提高的幅度就更大了。这一点还可以从非晶的最佳磁退火温度不是在Tc附近,而是在低于Tc几十度这一点得到证明。3．磁退火前后这两种非晶软磁合金的交流损耗曲线(P／f-f曲线)的走向不同。非晶软磁淬火态的损耗曲线很特殊,在低频段,每周损耗P／f随频率的增加而增加,在2KHz-v4KHz频率范围内,每周损耗反常地随频率增加是减少的,并出现一个最小值,然后在4KHz之后又随频率的增加而增加,但增加的量不很大。非晶合金经磁场热处理后损耗曲线的走向又趋正常,与晶态软磁的损耗曲线一致。这可能与非晶态软磁合金在磁退火前的畴结构特殊有关,据文献介绍,非晶软磁合金在淬火态的畴结构远不同于晶态软磁,主要是迷宫畴,而磁退火后磁畴主要为180°畴,这样使淬火态的非晶软磁在损耗曲线上表现出反常现象,而磁退火使非晶磁畴结构变得与晶态软磁类似了。4．本试验所用的两种非晶软磁合金经磁退火后其总损耗有所下降,但仍略大于晶态1J79软磁合金的总损耗。根据非晶软磁合金有较高的磁导率和较大的电阻率,应比晶态1J79的总损耗小,然而试验结果却与预想的相反。经损耗分离证明,非晶态软磁合金的经典涡流损耗和磁滞损耗占总损耗的比份较小,而反常涡流损耗占比份很大,可达70％；而晶态1J79的反常涡流损耗占的比份很小,只有6％左右,这种大的反常涡流损耗致使非晶的总损耗偏大。非晶反常涡流损耗大的原因,可能是由于它在磁退火后得到的巨大磁畴有关,根据文献介绍,非晶磁退火后的畴可比晶态的磁畴大几十倍。巨大的畴结构必然带来一些经典涡流损耗中没有包括的内容,如微观涡流损耗等。     

中镍软磁合金发展动向

本文概述了中镍软磁合金的基本特性;评述了国内外中镍软磁合金在理论研究、改善性能和发展应用等方面的动向;并对我国中镍软磁合金今后的发展提出了意见。     

高性能软磁合金的研究进展EI北大核心CSCD

软磁材料是一种极为重要且应用十分广泛的能源材料,近年来,随着磁性元件的日益高频化和小型化,以及节能环保的号召,开发和研究高性能软磁材料具有重要意义。本工作概述了软磁合金的发展历史,重点归纳出各类软磁合金(包括传统软磁合金、非晶/纳米晶软磁合金、高熵软磁合金)的成分、微观组织、磁性能以及应用范围,并总结出不同软磁合金的优、缺点;指出典型合金的微观组织对合金软磁性能(尤其矫顽力)具有关键性的主导作用,进而探讨了影响软磁合金矫顽力的因素及其微观机制,发现控制晶粒尺寸(或纳米粒子尺寸)是获得低矫顽力的关键,并描述了矫顽力的微观影响机制在高熵软磁合金中的发展;最后,展望了高熵软磁合金因多主元混合的成分特性带来的组织多样化,更有利于实现对合金性能的调控,并有望作为新一代高温软磁体材料。     

国外金属软磁材料近况

文献已对软磁合金国外近况作了全面介绍。本文仅就国外近期期刊和特种文献所发表的有关资料作一点滴介绍。内容包括:一、前言;二、现有软磁合金不断发展;三、软磁材料的应力敏感问题值得注意;四、发展新型的存储器用的磁性材料;五、软磁复合材料。     

剧烈变形对Fe-50%Ni合金组织性能的影响

加工状态对软磁合金磁性能有很大影响。在常温和900℃对Fe-50%Ni(1J50)合金进行50%冷热剧烈变形处理,利用金相显微镜和软磁测量系统对不同处理方式软磁合金的组织结构和性能进行表征。结果表明,剧烈变形对Fe-50%Ni合金的组织结构产生重大影响;Fe-50%Ni合金经过50%冷、热剧烈变形后的磁滞回线圆润,磁损耗增加,磁性能有所下降。     

多次固化对复合材料性能的影响

为了更好地研究多次固化对复合材料性能的影响,研究了多次固化对复合材料层合板的力学性能、介电常数和损耗角正切值的影响,还研究了蜂窝夹芯结构复合材料的剥离强度。结果表明:随着固化次数的增加,层合板的拉伸强度、压缩强度、弯曲强度几乎不发生变化,剪切强度随固化度增加有所提升;介电常数和损耗角正切值的变化幅度不大;同时,蜂窝夹芯结构复合材料的剥离强度随固化次数增多有所降低。多次固化基本不影响复合材料耐受大功率电磁的性能。     

黏弹阻尼层共固化复合材料不同温度下的阻尼性能

采用共固化工艺制备了以丁腈橡胶为黏弹性阻尼层的复合材料 , 应用动态机械分析仪(DMA)测定了该材料损耗因子的温度谱 , 并对不同温度环境下该材料的阻尼性能和阻尼机制进行了分析。结果表明 : 当温度处于阻尼层玻璃态和高弹态区时 , 共固化复合材料损耗因子较小且随温度变化不大 ; 当温度处于阻尼层黏流态区时 ,共固化复合材料的损耗因子迅速增加到最大值后变小 , 最大损耗因子为 19. 2 % , 约为未插入黏弹阻尼层复合材料的 13倍; 共固化过程中阻尼层损耗因子的减小 , 使共固化复合材料的阻尼性能降低 , 并在阻尼层的黏流态区其损耗因子明显小于预报结果 ; 界面阻尼的影响提高了共固化复合材料的阻尼性能 , 并在阻尼层的玻璃态区其损耗因子大于预报结果。      

Wear-resistant magnetic head using amorphous alloy material

An audio recording/playback head using an amorphous (Fe-Co-Ru-Cr) ₇₅(Si-B)₂₅ alloy was developed. Compared with a commercial Sendust head, three excellent features were observed. The wear of the amorphous alloy head when used with γ-Fe₂O ₃ is two-thirds that of the Sendust head. The output level at high-frequency (14 kHz) is 5 dB higher than that of the Sendust head. The bias current for the amorphous alloy head is half that of the Sendust head     

Recent development of thin film materials for magnetic heads

Recent developments of soft magnetic film materials in the past decade are reviewed. Approximately 20 kinds of alloy systems with high saturation induction of more than 10 kG have been reported in the last decade, although there were only three conventional head materials: Mn-Zn ferrite, Permalloy, and Sendust. A particular focus of the review is nanocrystalline films and multilayer films. Also reviewed are improvements in single-layer homogeneous films of Fe, Fe-Si, Sendust, and Fe/sub 16/N/sub 2/. Almost all the materials reported are Fe-based alloys, and some alloys are nitrogen related: iron-nitride compounds or nitrogen-containing alpha -Fe or Sendust.<>     

Analysis of metal-ferrite interface layers in metal-in-gap heads

A metal-in-gap head structure in which the metal/ferrite interface is perfectly parallel to the main gap face was adopted for mass-production. An analysis of a pseudo-gap formed at the metal-ferrite interface by using sputter-assisted Auger electron spectroscopy is reported. In the case of a Sendust MIG head, it is confirmed that the pseudo-gap is a reacted layer at the metal-ferrite interface, which consists of Al₂O₃+SiO₂. The reaction mechanism is examined in the case of Sendust/MnZn-ferrite and a soft magnetic alloy, called Sofmax, and suitable barrier materials and thickness ranges. It is found that the reacted layer is reduced drastically by using a SiO₂ or SiN₂O 5-10 nm thick ultrathin barrier layer and Sofmax alloy film instead of Sendust. The ripple of a parallel-type metal-in-gap heads is found to be 0.5 dB or less     

Magnetic properties of sintered sendust alloys using powders granulated by spray drying method

The iron-silicon-aluminum alloys (particularly Sendust) have been widely used in applications requiring high saturation flux density, low coercive force and high electrical resistivity. For this reason they have been promising for magnetic thin film heads, however, they are too hard and brittle to be made into thin films by rolling, or into three-dimensional products of complex shape by mechanical working or a conventional powder metallurgy process. The reduction in the size and weight of devices that can be accomplished through the use of Sendust has had an important effect on technical development. In this report, magnetic characteristics of Sendust ring samples produced by the powder metallurgy process with spray drying were investigated. After gas-atomized Sendust powders were mixed with paraffin compounds, these powders were granulated by the spray drying method using organic binder consisting of polyvinyl alcohol (PVA) and plasticizer in the range from 0.1 to 0.5 wt% of PVA, in order to improve the powder flowability and mechanical strength of compacted bodies. Results show that the present method is an excellent process for producing near-net-shaped parts with high performance and high dimensional precision after sintering.     

Effect of secondary gaps in near-saturated metal-in-gap video heads

Secondary gaps between the ferrite bulk and the Sendust (AlFeSi alloy) shim may occur in metal-in-gap (MIG) heads. Finite-element models are used to explore the effect that these gaps have on the read/write characteristics of single- and double-sided MIG heads. The presence of a secondary gap is shown to cause an additional peak in the writing field and oscillations in the magnitude of the response during replay. The field and response of a double-sided MIG head is affected more than those of the corresponding single-sided MIG head     

Preparation by sputtering of thick sendust film suited for recording head core

A 12 μm thick film with large saturation flux density, 11 000 G, and high effective permeability, such as 240 at 20 MHz, was prepared by using tetrode sputtering equipment from a ternary alloy that consisted of Si:10.5 wt.%, Al:5.6 wt.%, and Fe:bal. (Si rich Sendust alloy) at a target voltage of 1000 VDC. These were the best conditions for obtaining the minimum value of coercivity with the glass substrate in our experiments. The electric resistivity and Vickers hardness of the film became greater than the same qualities in bulk alloys. The increase in effective permeability at high frequencies, and the higher resistivity and hardness are believed to originate from the granular structure of the film. In this study, it was proved that the magnetic properties, especially the coercivity and the initial permeability of the film were due, not only to the effect of magnetostriction and crystalline anisotropy, but also to the effect of film structure.     

高Br纳米晶Fe73Cu1Nb2V1.5Si13.5B9合金的铁损行为(I)低频损耗行为

在f=10-3×103Hz和Bm=0.1-1.0T范围内,研究了高Br纳米晶Fe73Cu1Nb2V1.5Si13.5B9合金的每周总损耗和频率的关系.P/f对f的行为明显地呈现非线性.大约在200Hz以下的范围内,非线性特征特别明显.用损耗统计理论中的"磁体"的行为能相当好地描述这种非线性行为.在较低的频段内,活动的磁体数n和动态过剩场Hexc是线性相关的,而在较宽和较高频段内,n与Hexc的关系是非线性的.     

载荷频率对金属及其合金高周疲劳特性的影响

采用超声高频加载方法进行高周疲劳试验时,应考察载荷频率对材料疲劳特性的影响。本文从微观组织结构和外部环境两方面论述了疲劳特性的频率效应,从裂纹扩展率、断口分析等方面回顾和介绍了频率对合金钢、钛合金、铝合金三类常用金属疲劳特性的影响,比较了三者异同。最后展望了高周和超高周疲劳研究的方向和方法及其在工程中的应用。     

塑料合金关于温度-频率-振幅的本构模型

以经典Kelvin分数导数理论为基础,建立新型BTG塑料合金的改进Kelvin分数导数动态本构模型,该模型综合描述了温度、频率和振幅与BTG塑料合金模量的关系.通过动态热分析仪DMA242,获取了BTG塑料合金几个温度下,振幅恒为30μm时的频率扫描和几个频率下的恒温幅值扫描的动态存储模量和损耗模量实验数据.首先分析频...     

Lattice parameters of ferromagnetic DO3-structured iron-aluminum-silicon alloys

The room temperature lattice parameters of DO₃ ordered Fe₃Al_xSi_1?x and of Fe₇₃Al_xSi_27?x alloys vary in smooth but non-linear fashions with respect to composition. In the case of the Fe₃Al_xSi_1?x alloys the magnitude and direction of the deviation from linearity is consistent with a variation in the degree of order with composition. New values are reported for the lattice parameters of the commercial alloy Sendust and for Alsifer 32.