Tuning of Microstructure and Magnetic Properties of Nanocrystalline NdFeB Permanent Magnets Prepared by Spark Plasma Sintering

Author

Ting Wang ; Ming Yue ; Yuqing Li ; Tokita, Masao ; Qiong Wu ; Dongtao Zhang ; Jiuxing Zhang

Author_Institution

Coll. of Mater. Sci. & Eng., Beijing Univ. of Technol., Beijing, China

Volume

6

fYear

2015

fDate

7/7/1905 12:00:00 AM

Firstpage

1

Lastpage

4

Abstract

Structure and magnetic properties were studied for bulk nanocrystalline isotropic and anisotropic Nd-Fe-B permanent magnets prepared by spark plasma sintering (SPS). The neck formation among the Nd-Fe-B powders, which was governed by sintering conditions in the SPS process, has a substantial influence on the microstructure and subsequent magnetic properties of the magnets. By tuning the current pulse ratio of power-on to power-off time during sintering from 12:2 to 2:2, we successfully reduced the thickness of the surface diffusion layer of the Nd-Fe-B particles in both hotpressed and hot-deformed magnets. As a result, the maximum energy product (BH)_max of the isotropic and anisotropic magnets increases by 27% and 9%, respectively.

Keywords

iron compounds; nanomagnetics; necking; neodymium compounds; permanent magnets; powders; sintering; surface diffusion; NdFeB; current pulse ratio; microstructure; nanocrystalline permanent magnets; neck formation; powders; spark plasma sintering; surface diffusion layer; Magnetic field measurement; Magnetic hysteresis; Magnetic properties; Magnetometers; Perpendicular magnetic anisotropy; Saturation magnetization; Current pulse ratio; Hard magnetic materials; Magnetic properties; Microstructure; Nanocrystalline Nd-Fe-B magnets; Spark plasma sintering; magnetic properties; microstructure; nanocrystalline NdFeB magnets; nanomagnetics; spark plasma sintering;

fLanguage

English

Journal_Title

Magnetics Letters, IEEE

Publisher

ieee

ISSN

1949-307X

Type

jour

DOI

10.1109/LMAG.2015.2464185

Filename

7177084