Enhancement of coercivity of hot-deformed Nd–Fe–B anisotropic magnet by low-temperature grain boundary diffusion of Nd60Dy20Cu20 eutectic alloy

Sepehri-Amin, H.; Liu, Jiangwei; Ohkubo, T.; Hioki, K.; Hattori, Atsushi; Hono, K.

doi:10.1016/j.scriptamat.2013.07.011

Cited by 118 publications

(29 citation statements)

References 21 publications

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“…However, tuning the magnetic properties of the grain boundary phase and studying its correlation to the coercivity is very challenging experimentally. Hence, micromagnetic simulations have been employed to study the in uence of the grain boundary phase composition and its correlation to the magnetization reversals 25,38,[40][41][42][43][44] . Figure 10 shows simulated demagnetization curves of a modeled hot-deformed magnet in which Nd 2 Fe 14 B grains are separated with 4 nm thick grain boundary phase 38) .…”

Section: Effect Of Grain Boundary Phase On Coercivity Of Ndfe-b Magnetsmentioning

confidence: 99%

Micromagnetic Simulations of Magnetization Reversals in Nd-Fe-B Based Permanent Magnets

2016

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Finite element micromagnetic simulation was employed to explain how the microstructure of Nd-Fe-B permanent magnets such as grain size, grain shape, and grain boundary composition in uence the magnetization reversals and coercivity. Micromagnetic simulations showed that local demagnetization factor decreases as grain size decreases, which is attributed to a higher coercivity in ne-grained anisotropic permanent magnets. Lower demagnetization factor is also responsible for a lower temperature dependence of coercivity in the magnets with a smaller grain size. It was also found that the reduction of the magnetization of the grain boundary phase in hot-deformed Nd-Fe-B magnets leads to the coercivity enhancement due to a stronger pinning force against magnetic domain wall motion. The coercivity of Nd-Fe-B magnets cannot be enhanced by the reduction of the grain size alone unless the grain boundary phase become non-ferromagnetic, indicating that the role of the grain boundary phase is more pronounced in the Nd-Fe-B magnets with a smaller grain size.

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Section: Effect Of Grain Boundary Phase On Coercivity Of Ndfe-b Magnetsmentioning

confidence: 99%

Micromagnetic Simulations of Magnetization Reversals in Nd-Fe-B Based Permanent Magnets

2016

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“…[1][2][3][4] The magnet consists of many tabular grains with diameters at the sub-micron scale and easy axes are oriented to almost the same direction. The grains interact with each other through exchange and dipole interaction and magnetization reversal process is controlled by these interactions.…”

Section: Introductionmentioning

confidence: 99%

Micromagnetic simulation for the magnetization reversal process of Nd-Fe-B hot-deformed nanocrystalline permanent magnets

et al. 2017

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We numerically demonstrated the magnetization reversal process inside a hot-deformed nanocrystalline permanent magnet. We performed large-scale micromagnetics simulation based on the Landau–Lifshitz–Gilbert equation with 0.1 billion calculation cells. The simulation model for the hot-deformed nanocrystalline permanent magnet consists of 2622 tabular grains that interact with each other by inter-grain exchange and dipole interactions. When the strength of the external field approached a coercive force, nucleation cores were created at the grain surface. The magnetization reversal was propagated by the inter-grain and dipole interactions. When the grains had overlapping regions parallel to the external field, the magnetization reversal propagated quickly between the grains due to the dipole interaction. In contrast, the motion of the magnetic domain wall was inhibited at interfaces between the grains perpendicular to the external field. Reversal magnetic domains had a pillar-shaped structure that is parallel to the external field. In the perpendicular direction, the reversal magnetic domain expanded gradually because of the inhibition of the domain wall motion.

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“…Now we continue this work including high-resolution structural characterization and extend our own as well as others work [21,22] by a systematic and comprehensive study of the effect of annealing, milling and low-melting eutectics on the magnetic properties and its microstructure for each processing step hot-compaction and die-upsetting. In contrast to other reports [23], where a high increase in coercivity was achieved only at the expense of a significant reduction in remanence due to the high amount of paramagnetic material incorporated in the magnet, we focus in this work on increasing coercivity without reducing remanence e.g. in adding the eutectics most economically.…”

Section: Introductionmentioning

confidence: 99%

Grain boundary diffusion in nanocrystalline Nd-Fe-B permanent magnets with low-melting eutectics

et al. 2016

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Enhancement of coercivity of hot-deformed Nd–Fe–B anisotropic magnet by low-temperature grain boundary diffusion of Nd60Dy20Cu20 eutectic alloy

Cited by 118 publications

References 21 publications

Micromagnetic Simulations of Magnetization Reversals in Nd-Fe-B Based Permanent Magnets

Micromagnetic Simulations of Magnetization Reversals in Nd-Fe-B Based Permanent Magnets

Micromagnetic simulation for the magnetization reversal process of Nd-Fe-B hot-deformed nanocrystalline permanent magnets

Grain boundary diffusion in nanocrystalline Nd-Fe-B permanent magnets with low-melting eutectics

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