The influence of the powder densification temperature on the microstructure and magnetic properties of anisotropic NdFeB magnets aligned by hot deformation

Lipiec, Wojciech; Davies, H.A.

doi:10.1016/j.jallcom.2009.11.047

Cited by 20 publications

(9 citation statements)

References 16 publications

(30 reference statements)

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“…For the investigated sample, exists good compatibility with the theory if we assume that in 70% of the grains the main mechanism of coercivity is pinning of domain walls, and in 30% nucleation of reversed domains. Designated by Lipiec and Davies [1], average grain size for this magnet had bimodal character (small grains up to 250 nm and large with size of several µm), which means that a large number of grains is greater than single domain particles. It is therefore possible that they are reversally magnetized by nucleation of reversed domains.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

“…Their unique properties are determined by: high density of the nal magnet, and a signicant degree of crystallographic texture. The densities of the produced magnets are in range from 91% to 99.6% of the densities of powders used in production process [1]. The crystallographic texture, obtained in the deformation process, results in formation of large magnetocrystalline anisotropy, which has signicant inuence on the magnetic parameters.…”

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confidence: 99%

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The Investigation of the Magnetization Reversal Mechanism in the Nd-Fe-B Type Magnet, Aligned by Hot Deformation

et al. 2012

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The magnetization reversal mechanism in the Nd16Fe78B6 hot densied magnet, aligned by means of die-upset forging has been investigated. The magnetic parameters have been derived from major hysteresis loop. The magnetocrystalline anisotropy constants K1 and K2 using SucksmithThompson relation modied by Ram and Gaunt have been calculated from the high eld measurements up to 5 T. These data have been used to determine the theoretical value of coercivity as a function of the angle Ψ0 between the sample easy axis and the applied magnetic eld direction. The experimental value of coercivity as a function of Ψ0 has been determined from the demagnetization curves measured for dierent Ψ0 angles. It was found that the best correlation between theoretical and experimental data have been achieved for magnetization reversal mechanism controlled partially by pinning of domain walls on grain boundaries and nucleation processes.

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Section: Materials and Experimental Proceduresmentioning

confidence: 99%

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confidence: 99%

The Investigation of the Magnetization Reversal Mechanism in the Nd-Fe-B Type Magnet, Aligned by Hot Deformation

et al. 2012

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Section: Introductionmentioning

confidence: 99%

“…Subsequent research found that the processing parameters, powder particle size, and added elements all have effects on the magnetic properties, but the deformation behavior and crystal orientation mechanism of the magnets remain unclear. [15][16][17][18][19][20] In this work, to further improve the uniformity of the magnet, we have improved the SSHD process. Before put into the copper tube, the magnetic powder was cold-pressed into bulk precursor.…”

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confidence: 99%

Preparation of Anisotropic Nanocrystalline NdFeB Magnets from Amorphous Powders by One‐Step Hot Deformation

Huang

Liao

et al. 2022

Adv Eng Mater

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The preparation of nanocrystalline anisotropic NdFeB permanent magnets generally includes two steps, hot pressing (HP) and hot deformation (HD). Herein, one‐step HD process is proposed to fabricate NdFeB magnets using amorphous powders. The effects of deformation ratio on the microstructure, magnetic properties, and corrosion resistance are investigated. Compared to traditional HP and HD process, one‐step HD can significantly reduce the volume fraction of coarse‐grain zone in the magnet. The increase of deformation ratio can promote the formation of the textured platelet‐shaped grains and uniform grain boundary phase. The magnetic properties, temperature stability, and corrosion resistance of the magnets increase with increasing deformation ratio until 80%. The best magnetic properties with intrinsic coercivity Hcj = 930 kA m−1, remanence Jr = 1.17 T, and maximum energy product (BH)max = 263 kJ m−3 have been achieved for the magnet prepared by one‐step HD, which are comparable to those obtained by conventional HP/HD. In addition, different Co element segregations are observed in the magnets with different deformation ratios, which have important effects on the Curie temperature and thermal stability of the magnets. The results suggest that, by replacing HP/HD process and using amorphous powder, one‐step HD can simplify the process while maintaining good properties.

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“…11 Many papers have reported the ways for making high performance hot deformed (HD) R 2 Fe 14 B-typed magnets with either disc or ring types. 10,[12][13][14][15] Only very limited papers have reported the inhomogeneity of the microstructure, texture and magnetic properties of HD R 2 Fe 14 B-typed magnets. [16][17][18] In this paper, the inhomogeneity on texture, microstructure and magnetic properties of HD disc shape R 2 Fe 14 B-type magnets along the radial and axial directions will be reported in detail.…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneity on texture, microstructure and magnetic properties of hot deformed R₂Fe₁₄B-typed magnet

Lee

Shih

Chang

et al. 2015

Int. J. Mod. Phys. B

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The inhomogeneity on texture, microstructure and magnetic properties of hot deformed (HD) disc shape R 2 Fe 14 B-typed magnets along radial and axial directions has been investigated. HD disc shape NdFeB magnet exhibits inhomogeneous texture, grain morphologies and magnetic properties not only along the radial direction but also along the axial direction. Higher magnetic properties can be found in the middle part of the HD magnet, due to the existence of larger volume fraction of plate-like Nd 2 Fe 14 B grains and the well c-axis alignment parallel to the pressing direction. In addition, particle-like and coarser grains are easily found not only in the bottom but also in the edge of the HD magnet, which may degrade the magnetic performance of the samples cut from those parts. Owing to the inhomogeneity of (00L) texture and grain morphologies along axial and radial directions, the optimal magnetic properties of Br = 12.7 kG, H ci = 5.1 kOe and (BH) max = 39 MGOe can be obtained only in the middle sample of HD magnet with slight polishing the top and bottom surfaces.

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The influence of the powder densification temperature on the microstructure and magnetic properties of anisotropic NdFeB magnets aligned by hot deformation

Cited by 20 publications

References 16 publications

The Investigation of the Magnetization Reversal Mechanism in the Nd-Fe-B Type Magnet, Aligned by Hot Deformation

The Investigation of the Magnetization Reversal Mechanism in the Nd-Fe-B Type Magnet, Aligned by Hot Deformation

Preparation of Anisotropic Nanocrystalline NdFeB Magnets from Amorphous Powders by One‐Step Hot Deformation

Inhomogeneity on texture, microstructure and magnetic properties of hot deformed R₂Fe₁₄B-typed magnet

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The influence of the powder densification temperature on the microstructure and magnetic properties of anisotropic NdFeB magnets aligned by hot deformation

Cited by 20 publications

References 16 publications

The Investigation of the Magnetization Reversal Mechanism in the Nd-Fe-B Type Magnet, Aligned by Hot Deformation

The Investigation of the Magnetization Reversal Mechanism in the Nd-Fe-B Type Magnet, Aligned by Hot Deformation

Preparation of Anisotropic Nanocrystalline NdFeB Magnets from Amorphous Powders by One‐Step Hot Deformation

Inhomogeneity on texture, microstructure and magnetic properties of hot deformed R2Fe14B-typed magnet

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Inhomogeneity on texture, microstructure and magnetic properties of hot deformed R₂Fe₁₄B-typed magnet