Title :
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
fDate :
7/7/1905 12:00:00 AM
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;
Journal_Title :
Magnetics Letters, IEEE
DOI :
10.1109/LMAG.2015.2464185
