Title :
Study on Ultrafine-Grained Sintered Nd–Fe–B Magnets Produced From Jet-Milled HDDR Powders
Author :
Guangfei Ding ; Shuai Guo ; Lingwen Cai ; Ling Chen ; Jian Liu ; Don Lee ; Aru Yan
Author_Institution :
Key Lab. of Magn. Mater. & Devices, Ningbo Inst. of Mater. Technol. & Eng., Ningbo, China
Abstract :
Ultrafine-grained sintered Nd-Fe-B magnets were produced from jet-milled hydrogenation-disproportionation-desorption- recombination powders in a proper sintering condition. The coercivity of ~15 kOe was obtained by sintering below 950 °C, and the average grain size was <;1 μm. For the newly fine-grained magnets, a higher magnetic field is needed to magnetize them, giving rise to a two-step initial magnetization curve involving domain wall pinning at the grain boundary phase. Microstructure observation indicated that the Nd-rich phases did not encapsulate the 2:14:1 phases effectively, resulting in defects and interactions between adjacent 2:14:1 grains, which are responsible for the relatively low coercivity of the fine-grained magnets.
Keywords :
coercive force; grain boundaries; grain size; iron compounds; magnetic domain walls; neodymium compounds; permanent magnets; powders; sintering; NdFeB; coercivity; domain wall pinning; grain boundary phase; grain size; hydrogenation-disproportionation-desorption- recombination powders; jet milled HDDR powders; magnetization curve; microstructure; sintered magnets; ultrafine grained magnets; Coercive force; Magnetic domain walls; Magnetic domains; Magnetic resonance imaging; Perpendicular magnetic anisotropy; Powders; Grain size; grain size; magnetic properties; microstructure; sintered Nd-Fe-B magnets; sintered Nd???Fe???B magnets;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2015.2437874
