共查询到20条相似文献,搜索用时 62 毫秒
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利用HDDR工艺制备出Nd32FebalBGax(x=0.0、0.2%、0.4%、0.6%、0.8%(质量分数))磁粉,并且对HDDR磁粉进行热压/热变形处理制备出全密度各向异性磁体。研究了热变形温度和Ga含量对Nd-Fe-B热变形磁体磁性能的影响,观测了不同Ga含量热变形磁体的微观结构,探讨了微量元素Ga的添加对用HDDR磁粉制备的热变形磁体微观结构和磁性能的影响机制。研究发现,Ga的添加能够明显减小热变形磁体的主相晶粒尺寸,改善磁体的微观织构,并可以同时提高热变形磁体的剩磁和矫顽力。当Ga含量为0.6%(质量分数)时,热变形磁体的磁能积达到最大值228.3kJ/m3。 相似文献
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Sievers S Braun KF Eberbeck D Gustafsson S Olsson E Schumacher HW Siegner U 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(17):2675-2679
The quantitative measurement of the magnetization of individual magnetic nanoparticles (MNPs) using magnetic force microscopy (MFM) is described. Quantitative measurement is realized by calibration of the MFM signal using an MNP reference sample with traceably determined magnetization. A resolution of the magnetic moment of the order of 10(-18) A m(2) under ambient conditions is demonstrated, which is presently limited by the tip's magnetic moment and the noise level of the instrument. The calibration scheme can be applied to practically any magnetic force microscope and tip, thus allowing a wide range of future applications, for example in nanomagnetism and biotechnology. 相似文献
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AbstractAn in situ microscopic observation of the magnetic orientation process of feeble magnetic fibers was carried out under high magnetic fields of up to 10 T using a scanning laser microscope. In the experiment, carbon fibers and needle-like titania fibers with a length of 1 to 20 μm were used. The fibers were observed to gradually orient their axes parallel to the direction of the magnetic field. The orientation behavior of the sample fibers was evaluated on the basis of the measured duration required for a certain angular variation. As predicted from the theoretical consideration, it was confirmed that the duration required for a certain angular variation normalized by the viscosity of the fluid is described as a function of the fiber length. The results obtained here appear useful for the consideration of the magnetic orientation of materials suspended in a static fluid. 相似文献
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It is demonstrated that the oft-times severe waveform distortion arising from the Shoenberg magnetic interaction in the de Haas-van Alphen effect can be very effectively suppressed when measurements are made on spherical samples in the presence of a uniform magnetic feedback field. A digital spectrum analyzer is used in conjunction with a large ramping modulation field (1 kG peak-to-peak) to obtain a Fourier transform of a portion of the dHvA waveform roughly every second, and the dHvA effect itself is used to provide criteria for setting the correct gain in the magnetic feedback loop. Examples drawn from a study of the [110] orientation in Pb serve to illustrate the advantages and improvements in waveform studies which accrue from the use of magnetic feedback. The improvement is particularly impressive in the three-harmonic method for determining the spin-splitting factor g
c
for extremal orbits on the Fermi surface, and the value g
c
= 0.704 is found for the [110] orbit in Pb ( oscillations). A careful search has been made for low-frequency dHvA oscillations in Pb corresponding to those reported in ultrasonic attenuation and magnetoresistance experiments, but no such oscillations could be found in the magnetization.This research was supported by the Natural Sciences and Engineering Research Council of Canada. 相似文献
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W. Wilczynski 《Journal of Materials Science》2003,38(24):4905-4910
Punching and packing in the process of production of magnetic cores for electrical machines result in the most significant deterioration of their magnetic properties. Specific total losses increase and magnetic polarization curve steepness decreases. This article presents a method that lets measure magnetic properties of cores following different methods of core packing. The effect has been shown of some technological operations in the production process of magnetic cores for electrical machines on their magnetic properties. 相似文献
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《International Journal of Engineering Science》1975,13(1):107-115
Some general mathematical expressions have been derived for the induced self and mutual inductances of the wires inside a cylindrical ferromagnetic shell. An application of these results is given. It is shown that the effect of the ferromagnetic shell on the inductances of the multiconducting wires is strongly geometry dependent; the closer the wires to the magnetic shell, the stronger the effect. For wires in the center of the cylinder, no significant result will be caused by the presence of the magnetic shell. 相似文献
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Iturriza N Fernández L Chizhik A Vara G Pierna AR del Val JJ 《Journal of nanoscience and nanotechnology》2008,8(6):2912-2922
Different kinds of magnetic anisotropies have been induced during the nanocrystallization process of Co- and Ni-rich amorphous ferromagnetic (Finemet) ribbons by the application of a constant stress or an axial magnetic field during the annealing process. Magnetization measurements have evidenced the presence od macroscopic anisotropy in the treated samples. The main goal of this work has been, after a careful DSC study, the structural analysis of the treated ribbons using X-ray Diffraction and Atomic Force Microscopy (AFM), detecting substantial differences in the crystallization state and grain size of the samples depending on the thermal treatment that was carried out. Moreover, AFM measurements revealed in all the treated samples a strong nanocrystallisation of the surface without evidences of amorphous matrix, which contrast with XRD measurements that have shown a high content of amorphous phase in the bulk of the ribbons. Magneto-optical Kerr effect measurements have been performed with the aim to elucidate the complex magnetic behaviour that is expected for the surface of the ribbons, measuring surface hysteresis loops that showed much higher coercive field values than that obtained in the bulk material. 相似文献
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介绍了纳米晶软磁材料所具有的独特结构和优异的磁性能。从纳米晶软磁材料的微观组织结构和宏观磁特性紧密相关的角度,探讨了铁基纳米晶合金的结构与磁性之间的依赖关系。 相似文献