Coercivity Enhancement of Dy-Free Sintered Nd–Fe–B Magnets by Grain Refinement and Induction Heat Treatment

Author

Ling Chen ; Xuejing Cao ; Shuai Guo ; Jinghui Di ; Guangfei Ding ; Changjiang Yan ; Renjie Chen ; Aru Yan

Author_Institution

Key Lab. of Magn. Mater. & Devices, Ningbo Inst. of Mater. Technol. & Eng., Ningbo, China

Volume

51

Issue

11

fYear

2015

Firstpage

1

Lastpage

3

Abstract

Using conventional N₂ gas jet milling, a coercivity of 19.01 kOe was obtained in Dy-free sintered Nd-Fe-B magnets with the grain size refined to 2.6 μm. Through the high-frequency induction heat treatment (HIHT) at 600°, the coercivity was enhanced to 20.56 kOe, while the remanence remained unchanged. The transmission electron microscope observation showed that the grain boundaries were broadened through the HIHT process. The increasement of coercivity may be related to the strong stirring effect of induction vortex, which facilitates the continuous distribution of the Nd-rich grain boundary phase and thus enhances the magnetic insulation between the matrix grains.

Keywords

boron alloys; coercive force; grain boundaries; grain refinement; grain size; heat treatment; high-frequency effects; iron alloys; milling; neodymium alloys; permanent magnets; remanence; sintering; transmission electron microscopy; Dy-free sintered Nd-Fe-B magnets; Nd-rich grain boundary phase; NdFeB; coercivity enhancement; conventional N₂ gas jet milling; grain refinement; grain size; high-frequency induction heat treatment; induction vortex; magnetic insulation; remanence; stirring effect; transmission electron microscope; Coercive force; Grain boundaries; Grain size; Magnetic domains; Magnetic resonance imaging; Perpendicular magnetic anisotropy; Coercivity enhancement; grain size; induction heat treatment; sintered Nd-Fe-B magnets; sintered Nd???Fe???B magnets;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2015.2435364

Filename

7112161