Title :
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
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;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2015.2435364
