Ordering of the α-Fe(Si) Crystallization Phase in Annealed Fe_(73.5)Cu_1Mo_3Si_(13.5)B_9 Alloy

The ordering of the α-Fe(Si) crystallization phase in annealed Fe73.5Cu1Mo3Si13.5B9 alloy has been studied using XRD method. The α-Fe(Si) phase in Fe73.5Cu1Mo3Si13.5B9 alloy annealed at 460℃ for 1 h consists of the DO3-type ordered region with spherical shape and disordered region. The size of DO3 ordered region increases with the annealing temperature. When the annealing temperature is 560℃, the size of the ordered region in the α-Fe(Si) grain is 14.0nm,which is nearly as large as that of the α-Fe(Si) grain (14.2 nm) and the degree of order of the α-Fe(Si) phase is about 0.78. When Fe73.5Cu1 Mo3Si13.5B9 amorphous alloy is annealed at 520℃, with the increment of the annealing time, the shape of the DO3 ordered region in the α-Fe(Si) phase is spheroidal at the beginning of the annealing and becomes spherical and has asize of 12.8 nm when the annealing time is 60 min. In addition, the DO3 superlattice lines of the α-Fe(Si) phase will vanish if Fe73.5Cu1Mo3Si13.5 B9 amorphous alloy is annealed for 1 h at 750℃.     

Fe基非晶和纳米晶合金的热膨胀

将非晶Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９和Ｆｅ９１Ｚｒ７Ｂ２合金经退火制成纳米晶合金，测量了淬火态和退火态样品的热膨胀曲线，研究了退火温度对热膨胀的影响，结果表明，纳米晶粒的形成导致居里温度Ｔｃ以下的热膨胀系数急剧增加，而Ｔｃ以上的热膨胀系数几乎不随退火温度变化。     

The migration behavior of atomic clusters in early nanocrystalline process of soft magnetic Finemet alloy

The Finemet alloys are commonly used as cores in transformers and generators, stress and field sensors in technological application for their excellent soft magnetic characteristics. To clarify the nanocrystallization mechanism of Finemet especially about the atomic migration in early stage is very essential for developing their distinctive characteristics. In this study, we investigate the migration behavior of atoms in order to clarify the mechanism of the early-stage nanocrystallization in amorphous Finemet alloys. The Fe(73.5)Si(13.5)B9Nb3Cu1 amorphous ribbons were prepared by single-roller melt-spinning process in argon atmosphere, and then annealed at 350 degrees C-400 degrees C for 10 minutes in vacuum. The atom force microscope (AFM) and the coincidence Doppler broadening spectra (CDB) were used to characterize the migration behavior of different atoms in Fe(73.5)Si(13.5)B9Nb3Cu1 amorphous alloy during the early-stage nanocrystallization. The X-ray diffraction (XRD) patterns show that all annealed samples are in the amorphous state. But the AFM observation shows clearly that there are many small atomic clusters (nuclei) which distribute in the amorphous matrix of the annealed samples. With increasing annealing temperature, there is a significant increase in the amount of atomic clusters and a dramatic drop in the average size of clusters with very limited Cu contention in the samples, which reflect the structural evolution into more homogeneity. The CDB spectrum indicates that the peaks of positron annihilation spectrum are gradually reduced, which means the number of grain boundary and the defects in samples are gradually increased. It can be concluded that more defects are introduced by the formation of atomic clusters through atomic migration during the early-stage nanocrystallization in Fe(73.5)Si(13.5)B9Nb3Cu1 amorphous alloys.     

Microstructure and Stability of Fe73.5Cu1Nb3Si13.5B9 Alloy at Different Stages of Phase Transformation

1. IntroductionStability of magnetic materials is very importals for application. It has been known that themagnetic stability and structural stability are closelyconnected. An effectual method for studying thendcrostructure instability is to measure magneticaftereffect (MAE)l'~']. There is a difference inthe MAE between the amorphous and the crystalline ferromagnetic materials, revealing distinctionof their microstructure. In this work, the MAE andthe microstructure were studied at differ…     

Cu和Nb对非晶态Fe—Si—B合金等温晶化过程的影响

采用示差扫描量热卡计（ＤＳＣＩ）得到了非晶态Ｆｅ－Ｓｉ－Ｂ合金加入Ｃｕ和Ｎｂ后的等温晶化放热曲线，结合Ｘ射线衍射（ＸＲＤ）分析，明确了Ｃｕ和Ｎｂ在形成纳米α－Ｆｅ（Ｓｉ）晶体相时的作用。此外，非晶态Ｆｅ７６．５Ｓｉ１３．５Ｂ９Ｃｕ１Ｎｂ３等温化的α－Ｆｅ（Ｓｉ）放热峰呈明显的非对称形状。     

V部分替代Nb对含Co FINEMET型合金磁性的影响

研究了含Co的Finemet型（Fe.．5Co0．5）73．5Nb3Si13．5B9Cu1和（Fe0.5Co0．5）73．5Nb2V1Si13．5B9Cu1合金在不同温度纳米晶化后的磁性．结果表明,用V部分替代Nb对淬态（Fe0.5Co0．5）73．5Nb2V1Si13.5B9Cu1非晶合金的居里温度没有明显的影响,但是形成（Fe0．5Co0．5）7a．5Nb2V1Si13．589Cu1纳米晶合金使剩余非晶中Co的含量降低,导致初始磁导率在高温下快速衰减;用V部分替代Nb使（Fe0．5Co0.5）73．5Nb2ViSi13．5B9Cu1纳米晶合金中的晶体相含有更多的Co,增大了材料的饱和磁感应强度B8并显著提高了初始磁导率．     

Influence of Annealing Conditions on Nanocrystalline and Ultra-Soft Magnetic Properties of Fe75.5Cu1Nb1Si13.5B9 Alloy

The magnetic and structural properties of FINEMET alloy with a composition of Fe75.5Cu1Nb1Si13.5B9 were investigated after primary and secondary crystallization of amorphous ribbon sample.The crystallization behavior and the nanocrystal formation of the samples were performed by differential thermal analysis(DTA) which in turn was supported by X-ray diffraction(XRD) study.Temperature dependence of initial permeability of amorphous and devitrified toroid shaped samples has been measured.Enhancement of Curie temperature of the amorphous alloy has been observed due to the irreversible structural relaxation.With the appearance of nanocrystalline phase the Curie temperature of the residual amorphous phase gradually decrease with the increase of annealing temperature.Their temperature dependence reflects the characteristic annealing temperature evolution of the basic magnetic parameters in these nanocrystalline systems.Saturation magnetization,Ms,increases with annealing temperature Ta for the samples and finally decreases during annealing at a temperature much higher than peak crystallization temperature.     

Influence of Magnetic Field Intensity on the Shape of the μ—T Curves for Fe73.5Cu1Nb3Si13.5B9 Alloy

Under different magnetic field intensities,the dependence of the permeability μon temperature T(μ-T curve) for the Fe73.5Cu1Nb3Si13.5B9 alloy annealed at 350-620℃ was investigated.The results showed that the magnetic field intensity had a remarkable influence on the shape of μ-T curves.For amorphous alloy,the sharp Hopkinson peak of μ-T curve disappeared gradually with the increase of magnetic field intensity.     

Nb和Si元素对提高纳米晶带材抗氧化能力研究

采用SEM和XRD等手段分析了Fe82Cu1B12Si4 Nb1与Fe73.5 Cu1 B7 Si15.5 Nb3纳米晶合金带材在空气中灼烧后的晶化产物和氧化产物;通过降低Nb和Si元素含量,提高Fe和B元素的含量,虽然使Fe82Cu1 B12 Si4 Nb1纳米晶合金具有高饱和磁感应强度和低的矫顽力,但却降低了它的非晶形成和抗氧化能力。根据K.Hono等采用原子探针法观察到的在晶化过程中各元素分布情况,提出了一个晶化过程模型,通过模型分析了纳米晶合金的抗氧化能力的原因;随着晶化过程推进,残余非晶相中Nb元素含量增加,使得残余非晶相区的晶化温度提高,同时发挥限制晶体长大的作用。     

Co-Finemet非晶合金晶化动力学及其纳米晶粉芯的磁性

利用单辊熔体快淬法在大气环境中制备了Fe73.5-xCoxSi13.5B9Cu1Nb3(x=10,30,50)非晶薄带,利用差示扫描量热法(DSC)研究了非晶薄带的晶化动力学行为。采用Kissinger和Ozawa方法计算了非晶薄带的晶化表观激活能,计算结果表明:随着Co含量的增加,一次晶化的表观激活能降低而二次晶化的表观激活能升高。利用Johnson-Mehl-Avrami(JMA)模型计算了非晶薄带一次晶化的局域Avrami指数m,计算结果表明非晶薄带一次晶化的机理在不同的晶化阶段是不一样的,晶化初期为扩散控制的三维形核和晶粒生长的整体晶化,晶化中后期为一维形核和晶粒生长的表面晶化,形核率近似为零。研究了Fe63.5Co10Si13.5B9Cu1Nb3纳米晶粉芯的磁性与球磨时间之间的关系,结果表明:纳米晶粉芯的有效磁导率表现出较好的频率稳定性,而且随着球磨时间的增加而减小,品质因子在低频范围内随着频率的增加而增加,在约80 kHz达到峰值,然后随着频率的进一步增加而逐渐减小。     

Giant Stress—impedance Effect in Amorphous and Current Annealed Fe73.5Cu1Nb3Si13.5B9 Ribbons

The giant stress-impedance(GSl) effect in amorphous and current annealed Fe73.5Cu1Nb3Si13.5B9 ribbons has been investigated .The results showed that the GSl effect changed drastically with annealing techniques and the maximum stress impedance ratio of 350% was obtained after optimal conditions of current annealing .The behaviors of the stress impedance vary with densities of annealing current and the stress longitudinally applied during current annealing.The maximum change of stress impedance existed in the sample annealed by high-current-density electropulsing under applied stress of 100MPa.     

Microstructure of Differently Annealed NanocrystallineFe_(72.7)Cu_1Nb_(1.8)Mo_2Si_(13)B_(9.5) Alloy

The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480℃ and 600℃ for 0.5 h. The experimental results show that the microstructure mainly consists of the nanoscale bcc α-Fe(Si) grains and the residual amorphous matrix phase. A trace paramagnetic phase was found for annealing about above 500℃. The volume fraction of cr-Fe(Si) grain increases with increasing annealing temperature, whereas the average size of grain is almost unchanged above 480℃ up to 580℃. The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperature.     

Si含量对纳米晶Fe_(87-x)Cu_1Nb_3Si_xB_9合金磁性能的影响

研究了Si含量对Fe87-xCu1Nb3SixB9合金经不同方式退火后磁性能的影响。结果表明:随Si含量的增加,Fe87-xCu1Nb3SixB9合金经普通退火后软磁性能逐渐得到优化;经磁退火后可感生出单轴磁各向异性,且磁退火特征随Si含量的增加而逐渐明显。根据横磁退火实验结果计算出的感生磁各向异性值Ku,则由26.7J/m3(Si=9.5at%)降低至14.1J/m3(Si=13.5at%)。由实验数据的分析认为Fe87-xCu1Nb3SixB9合金在高Si含量时经普通退火或纵磁退火后呈现优异的软磁特性,归因于析出的α-Fe(Si)相晶粒具有小的磁晶各向异性K1,从而导致合金具有更低的有效磁各向异性常数K所至。     

Thermal annealing dependence of high-frequency magnetoimpedance in amorphous and nanocrystalline FeSiBCuNb ribbons

The magnetoimpedance (MI) effect in Fe73.5Si13.5B9Nb3Cu1 melt-spun amorphous ribbons has been studied in the frequency range (1-500 MHz). Isothermal heating treatments in a furnace have been employed to nanocrystallize the ribbons (1 h at 565 degrees C in a vacuum of 10(-3) mbar), while other samples were annealed at lower temperatures (400 and 475 degrees C during 1 h), in order to evaluate the influence of the annealing temperature on the MI effect. The high-frequency impedance was measured using a technique based on the reflection coefficient measurements of a specific transmission line by using a network analyzer. Frequency dependence of the MI ratio, DeltaZ/Z, and both resistive, DeltaR/R, and reactive, DeltaX/X, components of magnetoimpedance were measured in the amorphous and annealed states, at different temperatures. A maximum value of the MI ratio of about 50% at a driving frequency of 18 MHz is obtained in the nanocrystalline (annealed at 565 degrees C) ribbon. Maxima for DeltaR/R of about 81% at 85 MHz and DeltaX/X around 140% at 5 MHz were also achieved. It is revealed that the microstructural evolution in the nanocrystalline sample leads to a magnetic softening, an optimum domain structure and a permeability which is sensitive to frequency and applied magnetic field, generating a large MI response.     

稀土La改性铁基非晶带材组织结构与软磁性能研究

主要研究掺杂了不同含量稀土La后的铁基非晶带材Fe73.5Cu1Nb3Si13.5B9非晶带材组织结构与软磁性能.结果表明,随着稀土La掺杂含量的增加,Fe73.5Cu1Nb3Si13.5B9非晶带材的Fe-Si相的析出温度下降,而Fe-B相的析出温度则升高,一方面,非晶的热稳定性下降,另一方面,有利于控制Fe73.5...     

Effect of Annealing Temperature on Magnetic Aftereffect and Positron Lifetime in Fe73.5Cu1Nb3Si13.5B9 Alloy

1. IntroductionFe-based nanocrystalline materials, obtained byappropriately annealed amorphous ribbons above thecrystallization temperature, consist of a--FeSt finegrains and some residual amorphous phase. Thismicrostructure leads to their excellent soft magneticproperties, such as high saturation magnetization andhigh permeabilityll'2]. The quite effective methodo f studying the structure on an atomic scale is themeasurement of the MAE[3-5]. On the other hand,positron annihilation character…     

退火工艺对铁基非晶薄带磁感应效应的影响

研究了频率、磁场强度以及退火工艺对Fe73.5Cu1Nb3Si13.5B9非晶薄带磁感应效应变化幅度的影响.研究结果表明:磁感应效应变化幅度随着磁场强度的增大而增大,随着频率的升高呈现先增大后减小的趋势;与淬火态非晶薄带相比,退火可以提高磁感应效应变化幅度,且经300℃×1h退火后的磁感应效应变化幅度最大.     

电脉冲快速退火Fe73.5Cu1Mo3Si13.5B9合金的组织与磁性能

采用电脉冲快速退火实现了非晶合金Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５的纳米晶化。显微组织分析与磁性能测定结果表明,该合金经适当工艺的脉冲电流处理可得到较常规法晶粒密度更高、晶粒尺寸更小、软磁性能更优的纳米晶材料。基于随机无规磁各向异性模型,阐明了该合金的软磁性能与其显微结构的关系。     

电脉冲快速退火Fe_(73.5)Cu_1Mo_3Si_(13.5)B_9合金的组织与磁性能

采用电脉冲快速退火实现了非晶合金Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９的纳米晶化。显微组织分析与磁性能测定结果表明,该合金经适当工艺的脉冲电流处理可得到较常规法晶粒密度更高、晶粒尺寸更小、软磁性能更优的纳米晶材料。基于随机无规磁各向异性模型,阐明了该合金的软磁性能与其显微结构的关系     

Hopkinson Effect in Soft Magnetic Materials

1. IntroductionIt is well known that the initial permeability ofmany ferromagnetic materials increases with increasing temperature and appears a sharp peak just before the Curie point, and then drops off to a verysmall value. The peak is called the Hopkinson peakand the phenomenon is normally called the Hopkinson effectll]. Since this effect is valid for all the ferromagnetic materials, it has been used as a methodto measure the Curie temperature. However, in ourresearch work of nanocrystall…