Magnetization Process and Magnetic Microstructure of Nd-Fe-B HDDR Magnets

智仁, 槙; 哲, 広沢

doi:10.3379/msjmag.32.265

Cited by 6 publications

(4 citation statements)

References 3 publications

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“…In the case where the domain walls are inside the grain, those grains have multi-domain structures. This result agrees with former reports 7,8) .…”

Section: Magnetic Domain Observationsupporting

confidence: 94%

“…It was directly imaged that the domain walls motion in the grain with multi-domains is dominant in the weaker field, and that the magnetization reversal in the grain with a single domain is dominant in stronger fields. This tendency is shown more clearly in this study than in the previous reports 7,8) . Because we observed the magnetization of the bulk sample, not a thin film as in the case of Lorenz microscopy.…”

Section: Resultssupporting

confidence: 60%

“…Properties, especially the coercivity, of this bonded magnet are, therefore, also being intensively studied to maintain magnetic stability under high-temperature conditions. For this purpose, microscopic studies on crystalline and magnetic domain structures, which are related to the crucial factor to determine the coercivity, have been reported [3][4][5][6][7][8] .…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is not clear whether the grains of an HDDR bonded magnet have a single domain or multi-domain structure. Magnetic domain observations in a part of the magnetization process of the HDDR magnet using Lorenz microscopy or magnetic force microscopy (MFM) have been reported 7,8) , and they suggested that this magnet has a multi-domain structure in the thermally demagnetized state, and it has only a single-domain structure after applying a sufficiently strong magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Magnetization Mechanism for NdFeB Magnet Using Spin-Polarized Scanning Electron Microscopy (Spin SEM)

et al. 2009

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The magnetization process of Nd-Fe-B bonded magnets prepared by the Hydrogenation-Disproportionation-Desorption-Recombination (HDDR) process was studied by observing magnetic domain structures using spin-polarized scanning electron microscopy (spin SEM). The positional relationship between the grain boundaries and the magnetic domain walls is clearly imaged. The result revealed that these magnets contain grains with a multi-domain structure in the thermally demagnetized state. The domain wall motions in grains with multi-domains are dominant in weak magnetic fields in the initial magnetization process, whereas fraction of the grains with a single domain increases with further increasing the magnetic field. The coercivity variations in these grains were also visualized.

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“…In the case where the domain walls are inside the grain, those grains have multi-domain structures. This result agrees with former reports 7,8) .…”

Section: Magnetic Domain Observationsupporting

confidence: 94%

Section: Resultssupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Analysis of Magnetization Mechanism for NdFeB Magnet Using Spin-Polarized Scanning Electron Microscopy (Spin SEM)

et al. 2009

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Spin-Polarized Scanning Electron Microscopy

Kohashi

2015

Advances in Imaging and Electron Physics

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Magnetic domain observation of hydrogenation disproportionation desorption recombination processed Nd–Fe–B powder with a high-resolution Kerr microscope using ultraviolet light

Takezawa¹,

Maruko²,

Tani³

et al. 2010

Journal of Applied Physics

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A Kerr microscope that uses ultraviolet (UV) light for high-resolution domain observation was built, and the domain structure and magnetization process of hydrogenation disproportionation desorption recombination (HDDR) powder were examined. The UV Kerr microscope could observe nanometer-sized domain patterns. Applying a dc field of 1.0 kOe to HDDR powder at a desorption recombination (DR) time of 12 min produced abrupt wall motion. The pinning force exerted by the grain boundaries is inadequate for producing high coercivity because the Nd-rich phase layers along these boundaries are absent at a DR time of 12 min. For HDDR powder at a DR time greater than 14 min, changing the magnetic field by up to 1.0 kOe produced no observable wall motion. It follows that the high coercivity of HDDR powder is due to domain wall pinning at the grain boundaries.

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Magnetization Process and Magnetic Microstructure of Nd-Fe-B HDDR Magnets

Cited by 6 publications

References 3 publications

Analysis of Magnetization Mechanism for NdFeB Magnet Using Spin-Polarized Scanning Electron Microscopy (Spin SEM)

Analysis of Magnetization Mechanism for NdFeB Magnet Using Spin-Polarized Scanning Electron Microscopy (Spin SEM)

Spin-Polarized Scanning Electron Microscopy

Magnetic domain observation of hydrogenation disproportionation desorption recombination processed Nd–Fe–B powder with a high-resolution Kerr microscope using ultraviolet light

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