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1.
Uniaxial magnetic anisotropy has been induced in amorphous Fe73.5Cu1Nb3Si15.5B7 (Fe-rich) and (Co77Si13.5B9.5)90Fe7Nb3 (Co-rich) ferromagnetic alloys by annealing under stress and/or magnetic field. Such anisotropy plays a crucial role on the magnetization process and, consequently, determine the future applications of these materials. The mechanisms involved on the origin of such induced magnetic anisotropy showed significant differences between Fe-rich and Co-rich amorphous alloys. This work provides a comparative study of the coercive field and induced magnetic anisotropy in Fe-rich and Co-rich (Finemet) amorphous alloys treated by stress and/or field.  相似文献   

2.
铁基纳米晶合金介观结构的等效RLC并联模型   总被引:3,自引:0,他引:3       下载免费PDF全文
根据实验研究成果提出纳米晶合金软磁性能受其介观结构影响的观点,建立了Fe基纳米晶合金的球状介观结构模型,分别求出只有交变磁场或交变磁场和静磁场作用时纳米晶粒球的频率函数——D函数.分析表明,两种D函数都是复变函数,其实部Re(D)为纳米晶电感性质和电容性质的反映,虚部Im(D)为纳米晶电阻性质的反映,据此建立了Fe基纳米晶合金介观结构的等效RLC并联模型.由该模型求得合金产生极值巨磁电阻的条件为vextGMI=v|Re(D)=0,决定因素有μ,σ,ω,R和Hex及微观磁结构. 关键词: Fe基纳米晶合金 等效RLC并联模型 球状介观结构模型 频率函数  相似文献   

3.
Fe73.5Cu1Nb3B9Si13.5非晶态合金的激波纳米晶化研究   总被引:3,自引:0,他引:3       下载免费PDF全文
周效锋  刘应开  刘佐权  李德修 《物理学报》1999,48(11):2098-2103
实验表明,非晶态合金在激波影响下会转变为纳米晶.最近的实验进一步发现,Fe73.5Cu1Nb3B9Si13.5非晶态合金中的Cu,Nb在激波晶化中的细化作用被抑制,且样品在这种转变之后作进一步的退火处理,其晶粒度变大而晶格常数变小.在激波晶化机理分析中提出了“激波流体晶化”构想. 关键词:  相似文献   

4.
频率对纳米晶软磁合金磁性能影响的理论解释   总被引:3,自引:0,他引:3       下载免费PDF全文
杨全民  王玲玲 《物理学报》2005,54(9):4256-4262
根据原子力显微镜(AFM)对Fe基纳米晶Fe735Cu1Nb3< /sub>Si135B9合金薄带的介观结构的研究结果,提出了解释纳米晶软磁合金磁性能的理论模型——柱、球混合模型,并成功地解释了频率对纳米晶软磁合金磁性能的影响,所得理论体现了Herzer理论和纪松理论的特点,并弥补了它们的不足,同时提出了纳米晶粒电导率σ、磁导率μ对合金磁性有影响的观点. 关键词: 铁基纳米晶合金 模型 频率 软磁性能  相似文献   

5.
用原子力显微镜(AFM)观测了不同张应力退火的Fe基纳米晶(Fe73.5Cu1Nb3Si13.5B9)薄带横断面的形貌,并结合X射线衍射(XRD)图谱对不同张应力退火的Fe基纳米晶薄带的介观结构进行分析;测量了不同张应力退火Fe基纳米晶薄带的纵向驱动巨磁阻抗(LDGMI)曲线及横向磁各向异性场;认为张应力退火Fe基纳米晶薄带感生横向磁各向异性场的介观结构机理,是由于外加张应力退火产生由非晶相包裹着的α-Fe(Si)纳米晶粒(包裹晶粒)的横向优势团聚. 关键词: 应力退火 介观结构 AFM 团聚  相似文献   

6.
The changes of quasi-static magnetic hysteresis loops and X-ray diffraction patterns of the Fe73.5Si13.5B9Nb3Cu1 doped to 10 at % chromium instead of iron have been studied to elucidate the influence of the thermomechanical treatment consisting of annealing and cooling of the alloy under the tensile stress (tensile-stress annealing (TSA)) on the magnetic properties and the structure of these alloys. It is shown that the treatment results in the induction of the magnetic anisotropy of the hard axis type at which the magnetization reversal along the direction of applying the external stress during annealing is hampered. The energy of the induced magnetic anisotropy decreases as the chromium content increases. During TSA, the nanocrystal lattices are deformed, and the deformation is retained after cooling. The interplanar spacings increase along the extension direction and decrease in the transverse direction. The deformation anisotropy is observed for crystallographic directions. The anisotropic deformation of the bcc lattice of nanocrystals with high content of the ordered Fe3Si phase characterized by a negative magnetoelastic interaction is the cause of formation of the state with the transverse magnetic anisotropy of the hard axis type.  相似文献   

7.
退火加热速度对Fe-Cu-Nb(V)-Si-B纳米晶合金磁性的影响   总被引:3,自引:0,他引:3       下载免费PDF全文
研究了退火温度为550℃的纳米晶化过程中加热速度对Fe72.7Cu1Nb2V1.8Si13.5B9与Fe73.5Cu1Nb3Si13.5B9合金磁性的影响.磁性测量结果表明,退火加热速度对这两种合金软磁性能有明显的影响,快速加热可显著提高合金的初始磁导率μi 关键词:  相似文献   

8.
The influence of nanocrystallization conditions on the structure, magnetic properties, and temperature stability of nanocrystalline magnetically soft Fe73.5Cu1Nb1.5Mo1.5Si13.5B9 alloy is studied. It is found that preliminary low-temperature annealing exerts an influence on subsequent nanocrystallization of the alloy. In addition, preannealing followed by nanocrystallization considerably improves the magnetic properties of the alloy. It is shown that the magnetic properties of the material can be controlled by varying the frequency of a magnetic field used for thermal treatment causing nanocrystallization. It is established that the magnetic properties of nanocrystalline Fe73.5Cu1Nb1.5Mo1.5Si13.5B9 alloy offer a high temperature stability.  相似文献   

9.
The results obtained by partially substituting Ge for B and Si in the FINEMET alloy for the purpose of improving its magnetic properties at high temperatures are presented in this work. Nanocrystalline ribbons were obtained from controlled crystallization of amorphous material made employing the melt spinning technique. The studied compositions were: Fe73.5Si13.5Ge2Nb3B7Cu1 and Fe73.5Si13.5Ge4Nb3B5Cu1. The structural evolution of these alloys was studied using X-ray diffraction (XRD) and differential scanning calorimetry (DSC) and these results were correlated with their magnetic properties at different annealing temperatures. The coercivity obtained for both alloys was below 1 A/m at anneling temperatures between 773 and 823 K. The amorphous saturation magnetization was satisfactory, almost 137 emu/g, comparable with that obtained for FINEMET alloys. The nanocrystallization and the Curie temperatures are dependent on Ge concentration.  相似文献   

10.
Over the last years several works have been published in which magnetic and structural properties of soft magnetic nanocrystalline alloys were reported. Among these, there are a series of articles where the nanocrystals composition of FINEMET-type alloys with Ge addition was obtained by Mössbauer spectroscopy (MS) and X-ray diffraction (XRD). By considering a linear relationship between the magnetic moments of the nanocrystals and the composition of various elements in these crystallites, the magnetic moment of the nanocrystals was calculated. This paper reviews results obtained by different authors since 1980 and they are compared with ours. In turn, we revised some elements not previously considered for the calculus of the nanocrystals composition that allowed us to obtain the magnetic moment of the crystallites in the alloy. In particular, we analyzed FINEMET-type alloys with replacement of B for Ge: Fe73.5Si13.5Ge2B7Nb3Cu1 and Fe73.5Si13.5Ge4B5Nb3Cu1. The nanocrystalline structure was obtained by isothermal annealing of melt-spun ribbons at 823 K for 1 h. From MS and XRD we obtained the atomic composition of the nanocrystals in the magnetic material. The magnetic contribution of the nanocrystals to the alloy was calculated using a linear model and the results were compared with experimental measurements of the samples.  相似文献   

11.
The Curie temperatures (Tc) of metastable nanophases have been investigated in partially crystallized Fe73.5Cu1Nb3Si13.5B9 and Fe86Zr7Cu1B6 nanostructured soft magnetic alloys as a function of annealing temperature and time. It is shown that for both materials a supersaturated phase is formed which transforms only at the second stage of crystallization by dissolution of the solute elements monitored by the steep increase of Tc.  相似文献   

12.
在激光功率为40—160W、扫描速度为10mm/s、激光光斑为20mm照射条件下,用CO 2激 光辐照非晶Fe73.5Cu1Nb3Si13.5B9< /sub>产生微量晶化.利用透射穆斯堡尔谱 (TMS)技术分析了原始态和晶化后样品的超精细结构.确定了穆斯堡尔谱的基本参数——化 学位移(IS)、四极分裂(QS)、内磁场(Hhf)随激光功率变化的规律.分析表明,CO2关键词: 激光辐照 微量晶化 73.5Cu1Nb3 Si13.5B9')" href="#">非晶Fe73.5Cu1Nb3 Si13.5B9 穆斯堡尔谱  相似文献   

13.
The magnetic and magnetoelastic parameters of Fe64Co21B15 and Fe81.5B13.5Si3C2 amorphous ferromagnetic alloys treated by direct electric current in air are studied as functions of the applied magnetic field and current density. The samples of the alloy have the form of narrow strips with different lengths. It is found that the magnetoelastic parameters of the dc-treated alloys depend on the magnetic field in a qualitatively different way. From the behavior of the magnetic and magnetoelastic parameters of the alloys in the magnetic field a model of magnetization nonuniform distribution in amorphous ferromagnetic alloys subjected to dc treatment is proposed.  相似文献   

14.
This paper presents the results of investigation on the influence of temperature on magnetoelastic characteristics of the two ring-shaped cores, made of Fe70Ni8Si10B12 amorphous alloy. The cores were annealed for 1 h at 350 and 400°C, respectively. The compressive force F was applied perpendicular to the direction of the magnetizing field H in the sample. Special cylindrical backing enables application of the uniform compressive stress σ to the wound ring sample. A resistive furnace heated the experimental set-up. Results presented in the paper indicate a significant influence of the temperature on the magnetoelastic characteristics of Fe70Ni8Si10B12 amorphous alloy. Information about the magnetoelastic characteristics of this material may be useful in the magnetoelastic sensor development. Also this will create new possibilities in the development of physical model of magnetoelastic effect.   相似文献   

15.
Fe73.5Cu1Nb3Si13.5B9 and Fe72.5xCu1Nb4.5Si10+x+y B12–y alloys are compared from the point of view of crystallisation behaviour and changes in the short-range order in the amorphous reminder. The increase in Nb to 4.5 at.% in the latter system slows down the formation of nanocrystals to approximately 40% even after 16 hours of anneal at 550 °C forx=0.5,y=3. Segregation-induced changes in the short-range order are manifested via hyperfine field distributions corresponding to the amorphous reminder.  相似文献   

16.
The influence of the thermal treatment type on the temperature dependences of the magnetoimpedance of nanocrystalline Fe73.5Si16.5B6Nb3Cu1 alloy strips is investigated. The main mechanisms determining the temperature behavior of the magnetoimpedance of strips with induced magnetic anisotropy having various special features are established. The prospects for application of the alloy strips nanocrystallized in the presence of a magnetic field as sensitive elements of temperature sensors and special magnetic field detectors are demonstrated.  相似文献   

17.
The local environment of Cu atoms in Fe73.5Cu1Nb3Si13.5B9 alloy was investigated by extended X-ray absorption fine structure(EXAFS).Cu clusters began to order when the annealing temperature was around 733 K from the results of the Fourier transform curves.The fitting results showed that the first shell of the near fcc(face-centered cubic)Cu clusters only contained Cu atoms.The coordination number increased with the annealing temperature.Subsequently,the occupancy rate increased from 33.3%(annealed at 733 K)to 100% (annealed at 853 K).This local structural change of Cu atoms could probably affect the distribution of the bcc(body-centered cubic)α-Fe in Fe73.5Cu1Nb3Si13.5B9 alloy.  相似文献   

18.
何开元  智靖  熊湘沅  程力智 《物理学报》1993,42(10):1691-1695
研究了成分为Fe73.5Cu1Nb3Si13.5B9的纳米晶体结构的软磁材料的磁各向异性。理论分析及测量结果说明,用趋近饱和的磁化过程可以测定出这种材料中的有效磁各向异性常数,它比晶粒中的磁晶各向异性常数K1约小一个数量级。 关键词:  相似文献   

19.
The ferromagnetic resonance linewidth of Fe73.5CuNb3Si13.5B9 melt-spun ribbons has been investigated as a function of annealing temperature. Fe73.5CuNb3Si13.5B9 possesses an ultrafine grain structure which can be altered by suitable annealing to exhibit a combination of excellent soft magnetic characteristics and high saturation induction. It is a ferromagnetic metal consisting of crystallites whose anisotropy axes are randomly oriented and which may interact with each other via exchange or dipolar fields. When annealed at moderate temperatures, Fe73.5CuNb3Si13.5B9 is characterized by an extremely low coercive field, and is useful in magnetic cores and memories. At a critical temperature (∼600°C), the grain size rapidly increases with annealing temperature. This onset of crystallization is accompanied by a relatively abrupt increase in the FMR linewidth, the magnetic anisotropy field, and the coercive field. We extend the scaling arguments of Herzer to explain these obviously related phenomena.  相似文献   

20.
The structure and magnetic properties and the magnetoimpedance effect of nanocrystalline Fe73.5Si16.5B6Nb3Cu1 alloy ribbons, obtained from the amorphous state by annealing under different conditions, were comparatively analyzed. Despite the similarity of the samples’ structural states and the processes of their quasi-static magnetization reversal, the features of the magnetoimpedance effect are indicative of significant differences in the processes of their dynamic magnetization.  相似文献   

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