Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

Zhao, Lizhong; Deng, Xiangxing; Yu, Hongying; Guan, Hangjian; Li, X.Q.; Xiao, Zhiyu; Liu, Zhongwu; Grenèche, Jean‐Marc

doi:10.1016/j.jmmm.2017.07.044

Cited by 7 publications

(8 citation statements)

References 21 publications

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“…For instance, high-velocity compaction (HVC) has been proposed as an alternative method to prepare the precursor of the hot-deformed (HD) magnet. [48,49] Unfortunately, the low density of the reported HVC magnets leads to an aggregation of the amorphous grain boundary phase (GB aggregation) with a composition of Nd 37 Fe 63 (at%) in the hot-deformed magnet. Low-meltingpoint Nd 70 Cu 30 powders were chosen to compensate for the disadvantages of low density.…”

Section: Amorphous Grain Boundary Phasementioning

confidence: 99%

⁵⁷Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

et al. 2021

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This review summarizes the recent advances on the application of 57Fe Mössbauer spectrometry to study the magnetic and phase characteristics of Nd–Fe–B-based permanent magnets. First of all, the hyperfine structures of the Ce2Fe14B, (Ce, Nd)2Fe14B and MM2Fe14B phases are well-defined by using the model based on the Wigner-Seitz analysis of the crystal structure. The results show that the isomer shift δ and the quadrupole splitting ΔE Q of those 2:14:1 phases show minor changes with the Nd content, while the hyperfine field B hf increases monotonically with increasing Nd content and its value is influenced by the element segregation and phase separation in the 2:14:1 phase. Then, the hyperfine structures of the low fraction secondary phases are determined by the 57Fe Mössbauer spectrometry due to its high sensitivity. On this basis, the content, magnetic behavior, and magnetization of the REFe2 phase, the amorphous grain boundary (GB) phase, and the amorphous worm-like phase, as well as their effects on the magnetic properties, are systematically studied.

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Section: Amorphous Grain Boundary Phasementioning

confidence: 99%

⁵⁷Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

et al. 2021

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“…Recently, a new compaction method, high-velocity compaction (HVC), was proposed as an alternative method to prepare the precursor for an HD magnet [19,20]. This procedure possesses the advantages of high efficiency, low cost and room-temperature manufacture, compared to the hot pressing and spark plasma sintering (SPS) methods [8].…”

Section: On the Magnetism Of Grain Boundary Phase And Its Contributio...mentioning

confidence: 99%

On the magnetism of grain boundary phase and its contribution to the abnormal openness of recoil loops in hot-deformed magnets

Zhao¹,

Grenèche²

2019

J. Phys. D: Appl. Phys.

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The magnetism of grain boundary (GB) phase plays a critical role in the coercivity of Nd–Fe–B magnets. In this work, the aggregation of the GB phase was formed in the hot-deformed magnet due to the low-density high-velocity compaction (HVC) precursor. The ferromagnetism of GB aggregation was confirmed by the analysis of 57Fe Mössbauer spectrometry, and its correlation to the magnetic performance was investigated by micromagnetic simulation. Results show that the soft magnetic GB aggregation is responsible for the low coercivity of the hot-deformed magnet. Moreover, an abnormal large openness of the recoil loop under the reversal magnetic field HR was presented in this work, and the underlying mechanism is interpreted by introducing demagnetization energy. To compensate for the problem of low density, low-melting-point Nd70Cu30 powders were added into the HVC magnet, which makes the GB aggregation paramagnetic and enhances the coercivity.

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“…According to (1) [40], the maximum impact energy is 2323 J. Assuming that 80% of the energy stored in the spring can be converted into impact energy, the spring energy storage is at least 2903 J. Consequently, 3000 J of stored energy is chosen as the design parameter.…”

Section: Implementation Of High Impact Energymentioning

confidence: 99%

“…High-velocity compaction (HVC) is widely used in the powder metallurgy (PM) of titanium-, aluminum-, and ironbased alloys as well as magnets and other materials, for example [1][2][3][4]. Compared with conventional compaction (CC), HVC improves the green density of metal powders and enhances the uniformity of the density distribution [5].…”

Section: Introductionmentioning

confidence: 99%

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A Control Method of High Impact Energy and Cosimulation in Powder High‐Velocity Compaction

You

Liu

Guan

et al. 2018

Advances in Materials Science and Engineering

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To enhance the impact energy of powder high-velocity compaction (HVC) and thus improve the green density and mechanical properties of the resulting compacts, a mechanical energy storage method using combination disc springs is proposed. e high impact energy is achieved by modifying existing equipment, and the hydraulic control system is developed to implement the automatic control of the energy produced from the disc springs. An interdisciplinary cosimulation platform is established using the ADAMS, AMESim, and LabVIEW software packages to perform the interactive control of the simulation process and the realtime feedback of the simulation results. A mechanical-hydraulic cosimulation of the energy control virtual prototype of the testing machine is conducted using this platform. e influence of the impact energy on the green density is studied according to the HVC experimental results of the iron-based powders, and then, the green compact with the higher relative density is produced. e experimental results indicate that the energy enhancement method using the combination disc springs is reasonable and that the hydraulic control scheme is reliable.

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Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

Cited by 7 publications

References 21 publications

⁵⁷Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

⁵⁷Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

On the magnetism of grain boundary phase and its contribution to the abnormal openness of recoil loops in hot-deformed magnets

A Control Method of High Impact Energy and Cosimulation in Powder High‐Velocity Compaction

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Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

Cited by 7 publications

References 21 publications

57Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

57Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

On the magnetism of grain boundary phase and its contribution to the abnormal openness of recoil loops in hot-deformed magnets

A Control Method of High Impact Energy and Cosimulation in Powder High‐Velocity Compaction

Contact Info

Product

Resources

About

⁵⁷Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*

⁵⁷Fe Mössbauer spectrometry: A powerful technique to analyze the magnetic and phase characteristics in RE–Fe–B permanent magnets*