纳米晶Fe73.5Cu1Nb3Si13.5B9磁粉芯的磁性能研究

利用球磨纳米晶Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９合金得到的粉末压制成磁粉芯,研究其磁性。结果表明,在测量的频率范围内（１ｋＨｚ－１００ｋＨｚ）,该粉芯的磁导率几乎不随频率变化的而变化;粉芯的品质因数Ｑ随的增加而增加,在较高频率时有着比坡莫合金粉芯还要高的值,具有应用价值。推导出磁粉芯的静态磁导率的表达式发现分芯的磁导率与磁粉芯的密度有着密切的密度愈大,磁粉芯的静态磁导率愈高。     

Fe78Si13B9/铁氧体复合材料磁粉芯制备及其软磁性能

用Mn-Zn铁氧体溶胶对非晶Fe78Si13B9粉体包覆,模压成型制备了复合磁粉芯,并研究了复合材料磁粉芯的软磁性能.实验结果表明,铁氧体粉体在500℃×2h的热处理条件下逐渐生成,并在非晶Fe78Si13B9颗粒表面较好包覆;铁氧体溶胶的加入,大大提高了非晶Fe78Si13B9磁粉芯的品质因数Q值.当铁氧体溶胶量为7%、30℃的测试温度时,Fe78Si13B9/铁氧体复合材料磁粉芯的磁导率在1MHz时达到最大值32,Q值高达23.     

Fe基纳米晶／铁氧体复合材料磁粉芯制备及其软磁性能

用Mn-Zn铁氧体溶胶对Fe73.5Cu1Nb3Si13.5B9纳米晶包覆,模压成型制备复合磁粉芯,并研究了铁氧体溶胶量、热处理工艺及测试温度等因素对复合材料磁粉芯软磁性能的影响.实验结果表明,随着铁氧体溶胶量的增加,磁粉芯的磁导率减小,而Q值却随铁氧体溶胶量的增加有微小的增大.复合材料磁粉芯在热处理工艺为2h,500℃时,测试频率为500kHz,磁导率达到最大值.复合磁粉芯的品质因数Q值在200～1000kHz频段中,具有波动性,Q值在500kHz时达到51.测试温度对复合磁粉芯的磁导率和品质因数均有影响,测试温度从30℃升高到80℃时,磁导率从60.1降低到58.4,变化率为2.8%,而品质因数从59下降到54.     

Fe-6.5％Si/Fe73.5Cu1Nb3Si13.5B9纳米晶复合磁粉芯的制备及其软磁性能研究

采用Fe-6.5%Si粉末复合Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9纳米晶粉末制备了复合磁粉芯,并讨论了Fe-6.5%Si粉末复合量对复合磁粉芯磁性能的影响。结果表明,随着Fe-6.5%Si粉末的添加量从20%增加到80%,复合磁粉芯的密度几乎从5.46g/cm3线性增加到6.01g/cm3。复合磁粉芯的有效磁导率在20～500kHz的频率范围内具有良好的稳定性。随着Fe-6.5%Si粉末添加量从20%增加到80%,复合磁粉芯的有效磁导率几乎从33.7线性增加到38.3。复合磁粉芯的损耗随着Fe-6.5%Si粉末添加量的增加而增加。复合磁粉芯的直流偏置性能随着Fe-6.5%Si粉末添加量的增加而逐渐降低。当直流偏置场为7.96kA/m时,随着Fe-6.5%Si粉末添加量从0增加到80%,复合磁粉芯直流偏置性能从79.6%逐渐下降到62.2%。     

Fe/Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9纳米晶磁粉芯研究

采用Fe粉复合FeCuNbSiB纳米晶粉体制备了磁粉芯,并讨论了退火温度、Fe粉复合量、纳米晶粉体粒度以及绝缘剂等对磁粉芯磁性能的影响.结果表明,在200～350℃和350～400℃内退火,随着温度的升高,μ_e均呈先增大后减小,375℃时达到最佳;当复合Fe粉后,发现其软磁性能得到了明显改善, Fe粉量为40%时,μ_e达到最大,且在100kHz～1MHz内,频率稳定性良好,其中心频率在500kHz附近,并随Fe粉量的增加而向低频发生偏移.纳米晶粉体的粒度越大,磁粉芯的磁性能越好;粉体粒度为100～200目时,其μ_e达到最大.当375℃退火,由有机绝缘剂、40%(质量分数)Fe粉、100～200目纳米晶粉制备的磁粉芯,其μ_e达52.72、损耗Pu为0.01317J/m~3、Bs为3.92×10~(-3)T、Br=6.48×10~(-5)T、H_c为1.28A/m.     

Fe72.5Cu1Nb1.5Mo1.5V1Si13.5B9合金的磁性和晶化过程

本文研究了Ｆｅ７２．５Ｃｕ１Ｎｂ１．５Ｍｏ１．５Ｖ１Ｓｉ１３．５Ｂ９合金在不同热处理温度下磁性能的变化及其晶化过程。     

纳米晶软磁复合磁粉芯在中高频段性能研究

介绍了利用球磨后的FeCuNbSiB合金粉末冷压制作纳米晶复合磁粉芯的工艺.探讨了粉末粒度为80～200目,绝缘剂量为1%～8%时纳米晶复合磁粉芯的频率特性,直流叠加特性及品质因数Q.制备出的平均粒度为80目的磁粉芯有效磁导率μe在1MHz范围内恒为85,在100kHz时其峰值Q为65,在f=50kHz,Bm=50mT测试条件下其损耗为102mW/cm3.其功率损耗比传统铁粉芯,Fe-Ni粉芯小.     

应力退火对Fe73.5Cu1Nb3Si13.5B9纳米晶合金磁性能的影响

采用一种新的退火方式,将Fe73．5Cu1Nb3Si13．5B9合金薄带在铜环上卷绕成铁芯,研究在这种方式的退火过程中Fe73．5Cu1Nb3Si13．5B9合金薄带晶化时产生的张应力对其磁性的影响．结果表明：与普通退火相比,这种张应力使退火后合金的剩磁Br明显下降（最低为0.22T）,形成的感生磁各向异性的易轴垂直于张应力的方向．这种横向感生磁各向异性起因于纳米bccFe（Si）晶粒内通过内应力和负的磁滞伸缩引起的磁弹性作用。     

（FexCo1-x）73.5Cu1Nb3Si13.5B9合金高温磁性的研究

研究了460～640℃等温退火后纳米晶（FexCo1-x）73.5Cu1Nb3Si13.5B9（x=0.5，1）合金的初始磁导率麒随温度变化。与双相纳米晶Fe73.5Nb3Si13.5B9合金相比，（Fe0.5Co0.5）73.5Cu1Nb3Si13.5B9合金室温下的磁导率降低，但晶化相和非晶相居里温度明显升高，并显著提高了合金在高温下的软磁性能。初步探讨了改善纳米晶合金高温磁性的机理。     

Crystallization of amorphous Fe73.5Si13.5B9Nb3Cu1

A study is reported on the devitrification behaviour of the amorphous alloy Fe73.5Si13.5B9Nb3Cu1. Samples of the studied glass underwent isothermal and non-isothermal heat treatments in a thermal analysis apparatus. In addition some samples were very rapidly heated to very high temperatures by means of a laser beam. In this way a large temperature range was explored and information was obtained on the overall thermal evolution of the studied amorphous alloy. The experimental results suggest that, as recently proposed in the literature, nanocrystallization can be linked to a rate limiting Nb diffusion stage in the crystal growth process. However topological short range ordering (TSRO) and chemical short range ordering (CSRO) also affect the devitrification behaviour. In the case of the studied alloy, three temperature ranges can be defined. At low temperature only TSRO occurs. Above a temperature that lies approximately in the range 450–500°C, glass in glass phase separation occurs up to a temperature that lies approximately in the range 700–750°C, above which it appears to be very limited. The occurrence of glass in glass phase separation appears to be necessary to obtain a fine microstructure, because Nb concentrates in the boron depleted, iron rich glassy phase. The occurrence of TSRO prior to demixing should be avoided if nanocrystallization is desired. All this appears to be satisfied by isothermally treating the sample at a temperature of 555°C. This revised version was published online in November 2006 with corrections to the Cover Date.     

Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)纳米晶合金制备及其软磁性能

首先制备了Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)非晶合金带材并研究了微量Al在Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9-Al_(0.1)纳米晶合金中的影响情况。研究表明,微量的Al降低了Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)母合金的流动性;微量的Al促使Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)非晶合金在晶化热处理时的晶粒显著长大,降低了非晶合金中的内应力各向异性,由此提高了其晶化后的纳米晶合金100kHz以上频率的μe值,同时也显著降低其获得最佳软磁性能的晶化处理温度;晶化处理后,Al原子在Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)纳米晶合金中富集于α-Fe晶粒和富铜团簇内并且有可能形成了Fe_3Al;Fe_(73.4)Cu_1Nb_3Si_(13.5)B_9Al_(0.1)磁芯的最佳晶化处理工艺是545℃×1h,其磁芯在1,10,100和200kHz时的μe值分别为33 785,21 551,9 884和5 444。     

微波场作用下非晶合金Fe73.5Cu1Nb3Si13.5B9的纳米晶化

研究了微波场对晶化的影响.结果表明,将非晶合金Fe73.5Cu1Nb3Si13 5B9在微波场作用下在480℃短时间(5 min)晶化处理,形成体积分数为80%、尺寸约15nm的α-Fe(Si)相;适当延长晶化时间(30 min)使非晶合金完全晶化,α-Fe(Si)相的晶粒不再长大,原子层之间的距离降低至0.2461 nm,磁体具有最大Ms为1.79 T.与激光、激波、脉冲电场和脉冲磁场晶化处理相比,微波场晶化处理可同时获得单一的、更小晶粒尺寸和更高体积分数的α-Fe(Si)晶化相,使合金具有高的饱和磁化强度和优良的软磁性能.微波场有利于非晶合金中的硼原子向空位跃迁,使基体金属相α-Fe(Si)相的形核率增大,促进非晶合金的纳米晶化.     

Influence of annealing on the crystallographic structure and some magnetic properties of the Fe73.5Cu1Nb3-xUxSi13.5B9 nanocrystalline alloys

The influence of annealing on the structure and some magnetic properties of Fe73.5Cu1Nb3-xUxSi13.5B9 (x=1, 2, 3) alloys has been studied. The results confirmed the nanocrystalline character of these alloys in the temperature range 550–650 °C. The influence of the uranium content on the structural stability has been observed for annealing treatment at high temperature, i.e. at about 700 °C. The coercive field strongly depended both on the annealing temperature and on the uranium content. A minimum value of Hc was observed after annealing at 550 °C. Core losses of all alloys in the nanocrystalline state decreased with increasing uranium content. © 1998 Kluwer Academic Publishers     

Study of the crystallization kinetics in amorphous Fe73.5Cu1Nb3Si13.5B9 alloy

The kinetics of the crystallization of Fe_73.5Cu₁Nb₃Si_13.5B₉ amorphous alloy was studied using Mössbauer spectroscopy and X-ray diffractometry. During isothermal annealing of the samples, two phases were observed: a crystalline D0₃-FeSi alloy with fine grains and an amorphous phase enriched with niobium, boron and copper. It was found that the growth rate of the particles of the crystalline alloy was controlled by diffusion. For longer annealing time or at higher annealing temperature the growth process was found to be suppressed, probably by the niobium atoms. The activation energy obtained for the crystallization was about 143 kJ mol^–1.     

Electrical and Magnetic Transport Properties of Nanocrystalline Fe73.5Si13.5B9Cu1Nb3 Alloy

Electrical and magnetic transport properties of Fe_73.5Si_13.5B₉Cu₁Nb₃ (FINEMET) metallic ribbons prepared by standard melt-spinning technique have been investigated through dc and ac magnetic as well as electrical properties. Fe_73.5Si_13.5B₉Cu₁Nb₃ shows conventional anisotropic magnetoresistance (MR) which is found to vary from 1 to 15 %. The dynamic behaviour of the sample vibrating at a constant frequency with the help of an external transducer in an external magnetic field is investigated. It is observed that a small self-induced ac voltage is superimposed on the dc response of the sample. This small ac signal is observed to be periodic in nature and may be attributed to the presence of non-magnetic metallic species in the ribbon. The effect of temperature (ranging from 30 to 550 °C) on the resistivity of the sample is measured and the glass transition temperature (T _g) of the alloy is estimated from the dc resistivity anomaly observed at the elevated temperature. The frequency dependent responses of permeability, quality factor and dissipation factor are studied by Wayne Kerr impedance analyser with frequency range of 100 Hz–100 MHz. The observed electrical and magnetic properties of the material indicate that the alloy in its ribbon form is suitable for its potential use in electrical and magnetic switching devices.     

Nanocrystallization of Fe73.5Si13.5B9Nb3Cu1 soft-magnetic alloy from amorphous precursor in a magnetic field

The effect of a magnetic field on the nature of nanocrystallization from a melt-spun Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous precursor has been studied with the aim of controlling microstructures and magnetic properties. Annealing for magnetic crystallization was carried out at temperatures between the Curie temperature of the amorphous phase (586 K) and that of the crystalline phase (920 K). It was found that the {110} texture component in crystallized α-Fe(Si) phase increased in importance with increasing magnetic-field strength. An X-ray diffraction analysis based on the Shultz method revealed that the magnetic field caused preferential formation of {110}-oriented nuclei. In addition, the applied field enhanced crystallization kinetics, particularly the nucleation rate. No significant difference in grain growth behavior was observed as a result of applying a magnetic field. We therefore conclude that the development of the {110} texture by magnetic crystallization is predominantly attributable to preferential nucleation, rather than preferential growth, of {110}-oriented nuclei. The saturation magnetization of nanocrystallized specimens, evaluated using a vibrating sample magnetometer (VSM), was increased by the application of a magnetic field up to 4T during nanocrystallization.     

不同退火条件对Fe73.5Si13.5B9Cu1Nb3-xAlx磁导率的影响

用Al部分替代Nb制备了Fe73.5Si13.5B9Cu1Nb3-xAlx非晶条带,通过4种不同的退火方式得到其纳米晶样品,采用阻抗分析仪测量各样品的复数磁导率,并分析了退火方式对初始磁导率的影响.研究发现,经退火后,样品(除x=3.0)的磁导率有明显改善,明显高于经同样退火处理的Finemet配方的样品;对于不同退火方式,性能最好的样品Al含量不尽相同;对于不同Al含量的样品,有各自不同的最佳退火方式;对于x=3.0、完全不含Nb的样品,经随炉升温或降温退火后,仍然有较高的磁导率.研究结果表明,在Finemet配方中,用适量Al替代Nb,经适当退火后,样品的磁导率得到明显改善,从而提供了一条研制低成本高磁导率纳米晶合金的可能的途径.