Anisotropic Nanocrystalline Nd–Fe–B-Based Magnets Produced by Spark Plasma Sintering Technique

Author

Shu Liu ; Nam-Hyun Kang ; Lun Feng ; Sea-Hoon Lee ; Ji-Hun Yu ; Jung-Goo Lee

Author_Institution

Powder & Ceramics Div., Korea Inst. of Mater. Sci., Changwon, South Korea

Volume

51

Issue

11

fYear

2015

Firstpage

1

Lastpage

4

Abstract

Anisotropic hot-deformed nanocyrstalline Nd-Fe-B magnets were prepared by spark plasma sintering technique using MQU-F melt-spun flakes. Magnetic properties with a coercivity of 20 kOe and (BH)max of over 17.5 MGOe were obtained for the isotropic magnet after hot pressing (HP) process, due to the formation of superfine nanocrystalline grains without grain growth and coarse grain regions. Anisotropic Nd-Fe-B magnets were obtained with 60% and 80% degrees of deformation after die upsetting (DU) process. The remanence of 13.9 kG and (BH)max of 45 MGOe were achieved for the anisotropic Nd-Fe-B magnets with 80% degree of deformation. A distinct two-region microstructure with fine plated-shaped region and coarse grain region was formed in the vicinity of the flake boundaries after hot deformation. The microstructure evolution from HP process to DU process and the effect on the magnetic properties were discussed in detail.

Keywords

boron alloys; coercive force; grain boundaries; grain growth; hot pressing; iron alloys; magnetic anisotropy; nanofabrication; nanomagnetics; nanostructured materials; neodymium alloys; plasma materials processing; remanence; sintering; MQU-F melt-spun flakes; NdFeB; anisotropic hot-deformed nanocrystalline Nd-Fe-B magnets; anisotropic nanocrystalline Nd-Fe-B-based magnets; coarse grain regions; coercivity; die upsetting process; fine plated-shaped region; flake boundaries; grain growth; hot pressing; isotropic magnet; magnetic properties; remanence; spark plasma sintering technique; superfine nanocrystalline grains; two-region microstructure; Magnetic hysteresis; Magnetic properties; Magnetic resonance imaging; Microstructure; Perpendicular magnetic anisotropy; US Department of Defense; Hot deformation (HD); Nd-Fe-B magnets; Nd???Fe???B magnets; hot deformation; melt-spun flakes; microstructure; spark plasma sintering; spark plasma sintering (SPS);

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2015.2439672

Filename

7115931