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Magnetics, IEEE Transactions on

Issue 2 • Date June 1974

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Displaying Results 1 - 25 of 54
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Introduction to the soft magnetic materials 1 conference

    Page(s): 103
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    Freely Available from IEEE
  • Recent developments of soft magnetic alloys in Japan

    Page(s): 104 - 108
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    Soft magnetic alloys that are now in practical use or under development in Japan are reviewed. In the field of Si-Fe alloys, the influence of various processing parameters, such as addition of elements, heat treatments, and alloy composition on the mechanical and the magnetic properties and recent developments in methods of measuring iron losses are described and discussed. As for Ni-Fe alloys, the effects of refining reagents or added elements adjusting the formation of the superlattice Ni3Fe on the magnetic properties are given. Finally systematic studies on the relation between degree of order and magnetic properties of Ni-Mn alloys are reviewed. View full abstract»

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  • Magnetic transition and anomalous thermal expansion in R2Fe17compounds

    Page(s): 109 - 113
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    In R-Fe compounds, the magnetic properties are mainly determined by the Fe-Fe interatomic distances and the number of Fe nearest neighbors. Below the ordering temperatures, the R2Fe17compounds are generally ferromagnetic or ferrimagnetic colinear. The compounds with rare earth ions of small atomic radii, Ce2Fe17, Tm2Fe17, and Lu2Fe17, are exceptions; they are helimagnetic. At low temperatures they exhibit a transition either to a fan spin or to a ferrimagnetic colinear configuration. For all compounds, a negative thermal expansion is observed below their ordering temperatures. Negative interactions occuring mainly in the substitution zones are thus deduced. Varying strongly with distances, they lead to the observed anomalous thermal expansion, and being largest in the compounds with the shortest Fe-Fe distances, their helimagnetic structure is explained. View full abstract»

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  • Losses in silicon-iron

    Page(s): 113 - 115
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    Measurements of total power loss and domain-wall spacing have been made on individual grains in polycrystalline specimens of commercial grain-oriented 3% silicon-iron material. The loss-per-cycle against frequency characteristic of a grain is found to consist of discrete linear portions, which correspond to different domain-wall spacings. These changes in domain pattern result in a lower value of static hysteresis loss than expected and, therefore, a larger proportion of the total power loss must be attributed to the anomalous loss. From domain observations, it is concluded that a part of the anomalous loss is due to nonuniform flux distribution in the material and the overloading of the well-oriented grains. View full abstract»

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  • The effect of surface on the power spectrum of the Barkhausen noise in ferromagnetic materials

    Page(s): 115 - 117
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    The Barkhausen noise power spectrum was investigated on laminated polycrystalline toroids of Fe and 4% SiFe as a function of sample thickness; that is, of surface-to-volume ratio. Upon decreasing the thickness strong variations of spectrum shape are observed-the cut-off frequency increases and the spectral density drops in the very-low-frequency range. On the other hand, only negligible variations of static magnetic properties are observed. According to a recent theory, the results are explained assuming that a change of thickness directly affects the number of elementary pulses clustering into a large Barkhausen discontinuity. The calculated variations of the spectrum intensity and cut-off frequency are in good agreement with the experimental results. View full abstract»

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  • Barkhausen noise of 3% Si-Fe strips after plastic deformation

    Page(s): 118 - 120
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    Grain-oriented 3% Si-Fe strips were plastically strained up to \epsilon = 3 %. The frequency spectrum E(f) of the Barkhausen noise was measured. From E(O) a mean Barkhausen volume veffis calculated. The noise and veffare diminished after plastic deformation mainly already in the region \epsilon < 0.1 %, where the coercive field remains still constant, veffis related to a mean irreversible susceptibility, which is mainly determined by the hysteresis loop. By measurements of the correlation of the flux changes along the specimen a mean length of the Barkhausen volumes was obtained. Its diminution mainly causes the diminution of veff. The connection of the results with changes of the domain and dislocation structure is discussed. View full abstract»

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  • The influence of the crystallite orientation distribution function (ODF) on the magnetocrystalline anisotropy of a rimmed steel thin sheet

    Page(s): 120 - 122
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    The aim of this study is to relate the magnetocrystalline anisotropy at saturation to the texture function for a low-carbon steel. The texture has been calculated by expanding the direct pole figures as a series of spherical harmonics. This quantitative determination of textures permits one to calculate a theoretical curve of the variations of the torque in the rolling plane. These calculations are compared with the experimental curve. View full abstract»

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  • High-field susceptibility of invar alloys

    Page(s): 122 - 123
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    High-field susceptibility of iron-nickel alloys over the entire concentration range has been measured at 4.2 K. The temperature dependence of high-field susceptibility of alloys containing 29.1 and 32.7 at % Ni has been investigated in the temperature range from 4.2 to 150 K. Anomalous temperature dependence of the susceptibility of the alloys investigated can be explained by the existence of an antiferromagnetic phase at low temperatures. View full abstract»

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  • New grain-oriented silicon steel with high permeability "ORIENTCORE HI-B"

    Page(s): 123 - 127
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    A new grain-oriented silicon steel with a higher degree of grain orientation than usually obtainable by known conventional procedures was developed. The new material (HI-B) has made large improvements in core loss and magnetostriction characteristics by effects due to surface coating that are more remarkable with a higher degree of grain orientation. HI-B is 2-3 grade better than today's conventional products. Furthermore, there will be the possibility of improvement by 1-2 grade in the near future. HI-B has lower linear magnetostriction as compared to conventional material and is less sensitive to stress in spite of superior magnetic properties. Actual transformers made from HI-B materials have improved transformer characteristics such as core loss, exciting VA, and noise, reflecting the magnetic properties of materials. View full abstract»

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  • Some special cases of the magnetization processes of ferromagnets

    Page(s): 128 - 132
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    The subject of the reported work is the problems connected with the irreversible elementary magnetization processes, registered in the form of Barkhausen jumps, as well as the problems connected with the irreversible changes of the macroscopic magnetization of a ferromagnet in the process of the consecutive asymmetrical magnetization reversal and in the process of the periodic application of mechanical stresses. View full abstract»

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  • Influence of oxygen content on magnetic properties of Fe-Ni alloys

    Page(s): 136 - 139
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    58-percent Ni-Fe alloys have been investigated. It was found that the magnetic properties of the alloys depend on the whole chemical composition: matrix + alloying + impurity. The amount of impurities may be influenced deliberately by a proper selection of the atmosphere, temperature and time of the heat treatment. The effect of magnetic annealing was also investigated. Approximately linear relationship was found between the induced anisotropy constant and the suitably weighted average of oxygen and carbon contents. Our measurements suggest that the total amount of impurities in interstitial solid solution has an influence on value of the induced anisotropy constant. View full abstract»

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  • The effect of manganese on the magnetic properties of mumetal alloy

    Page(s): 139 - 140
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    The effect of manganese content and the baking temperature on the magnetic properties of Mumetal (76% Ni, 2% Cr, 5% Cu, bal. Fe) especially on the initial permeability has been studied. The most suitable combination was found for a manganese content of 0.3 to 0.5% at the baking temperature of 500 to 550°C. View full abstract»

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  • The effect of temperatures on the coercive field of polycrystalline wires of 72% Fe-Ni

    Page(s): 141 - 144
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    The present paper investigates the mechanism governing the coercive field in polycrystalline wires of Fe-Ni with 72% Ni, plastically deformed. Experimental results on the temperature dependence of the coercive field are reported, both when an external stress equal to the flow-stress is applied to samples and, successively, when it is released. The experiments are compared to the theoretical models based on the coherent rotation and mobility of the domain walls. View full abstract»

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  • Differential transformer cores for ground fault interrupting circuit breakers

    Page(s): 144 - 148
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    The magnetic requirements of differential transformers used in ground fault interrupters (GFI) for the sensing of 5 mA ground faults over the temperature range from -35°C to +66°C have been established. Ring laminations made of vacuum-melted permalloy and annealed so that the magnetocrystalline anisotropy K_{1} \sim 0 just above the maximum operating temperature meet these requirements. Such heat treatment will produce rings with low remanence in which the low-flux-density permeability is stable with temperature and changes little from the demagnetized to the remanent state. The processing of rings and the influence of impurities are briefly discussed. View full abstract»

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  • Problems in the design of power transformers

    Page(s): 148 - 150
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    The power loss of transformer cores can still be considerably reduced by improved joint design based on new knowledge of the localized flux distribution, both in the corners and in the limbs. Rotational flux has been measured in the T-joints of experimental cores, and it has been found to cause localized high loss regions dependent on the joint design. Circulating harmonic fluxes have been found in individual laminations in the limbs of three-phase cores. The path of the harmonics is independent of joint design although their magnitudes are dependent. Circulating 3rd harmonics as large as 0.3 T have been found in a core magnetized sinusoidally at 1.6 T. These cause additional losses calculated to be 20% of the nominal core loss, and great savings would be possible if the circulating harmonics could be reduced or eliminated. View full abstract»

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  • Soft-magnetic materials in large turbo-alternators

    Page(s): 151 - 154
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    The economic design of large turbo-alternators is greatly affected by the properties of the soft magnetic materials available for building them. The saturation magnetization of the stator iron effectively determines the power output of a machine of given physical size. Losses in the iron waste power, and so must be minimized, while increasing the depth of a stator core, to reduce losses, leads to increased transportation costs. Localized loss concentrations, particularly in the end region, can cause operational difficulties; the severity of the associated 'hot spots' depends not only on the electro-magnetic properties of the iron but on the thermal properties as well. Mechanical rigidity of the assembled core is also important; magnetically favorable materials might be rejected by a designer if too flexible. View full abstract»

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  • Measurement of magnetostriction and vibration with regard to transformer noise

    Page(s): 154 - 156
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    A simple technique of measuring the dynamic magnetostriction in silicon-iron using displacement transducers is discussed. The importance of stress and harmonics of magnetostriction is shown by considering the effects of improving the stress sensitivity of steel and reducing core vibration by a suitable bonding technique which can also reduce transformer noise. View full abstract»

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  • Single sheet tester for measuring core losses and permeabilities in a silicon steel sheet

    Page(s): 157 - 159
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    A new method which eliminates some disadvantages of the Epstein method has been developed for the rapid measurement of core losses and permeabilities at 50 or 60 Hz of single-sheet specimens. It is shown that the instrument has the following performance: 1) good correlation of the measured value with Epstein testing, 2) high stability, 3) simplicity of operation, and 4) use of a wide single-sheet specimen. View full abstract»

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  • Apparatus for the measurement of the magnetization of steel

    Page(s): 159 - 160
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    An improved method has been developed for measuring the magnetization of steel with great accuracy up to saturation. With toroidal samples it is not possible to reach the necessary field strength. Ellipsoidal samples are used, for which the magnetizing factor can be calculated exactly. The specimens are 200 mm long, have a maximum diameter of 10 mm, and are shaped accurately to within 0.01 mm. With this method magnetization curves can be obtained up to 105A/m with an accuracy of better than 1%. View full abstract»

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  • Iron-cobalt-vanadium alloys: A critical study of the phase diagrams in relation to magnetic properties

    Page(s): 161 - 165
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    A tentative explanation of some physical, magnetic, and mechanical properties in magnetically soft or semihard Fe-Co-V alloys is proposed in the light of present knowledge of their structural features. On account of important discrepancies, it is felt that metastable equilibrium diagrams, which are of greater significance for practical purposes, should be confirmed, and it would be of interest to redraw some parts of them with greater precision. View full abstract»

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  • Rotational hysteresis loss in silicon-iron single cyrstal with

    Page(s): 165 - 167
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    Rotational hysteresis loss has been measured on small discs of approximately 4% silicon-iron single crystal with View full abstract»

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  • Domain configuration under rotational flux and applied stress conditions in silicon-iron

    Page(s): 168 - 169
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    Measurements of power loss have been made on individual grains in polycrystalline specimens of commercial 3% grain-oriented silicon-iron under longitudinal and transverse ac magnetization and rotational flux conditions. The domain configurations have also been observed using a stroboscopic Kerr magnetic-optic apparatus. The effect of longitudinal stress and dc bias fields on the domain patterns and power loss under these ac magnetization conditions has also been investigated. It can be concluded that the highest power loss occurs under pure rotational flux conditions and that the application of longitudinal compressive stress increases the power loss, but to a lesser extent when a transverse ac flux is present. The application of a longitudinal dc field increases the power loss for all ac magnetizing conditions, and it has been observed that a longitudinal tensile stress has the opposite effect on the domain configuration to the application of a transverse dc field. View full abstract»

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  • Magnetic properties of Goss-textured Si-Fe sheets with the addition of Al

    Page(s): 170 - 172
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    Small additions of Si, Al, Ge... improve the magnetic properties of silicon-iron alloys. Goss-textured silicon iron with aluminum addition up to 2 wt% was produced by vapor deposition and subsequent diffusional annealing. After suitable treatment the total losses were reduced by about 12%. View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Meet Our Editors

Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology