US 11,705,257 B2
R-T-B sintered magnet and preparation method thereof
Yang Luo, Beijing (CN); Dunbo Yu, Beijing (CN); Wei Zhu, Beijing (CN); Xinyuan Bai, Beijing (CN); Xiao Lin, Beijing (CN); Shengjie Zhu, Beijing (CN); Zilong Wang, Beijing (CN); and Haijun Peng, Beijing (CN)
Assigned to GRIREM ADVANCED MATERIALS CO., LTD., Beijing (CN); Rare Earth Functional Materials (Xiong'an) Innovation Center Co., Ltd., Baoding (CN); and Griceon (Rongcheng) Co., Ltd., Weibai (CN)
Filed by GRIREM ADVANCED MATERIALS CO., LTD., Beijing (CN); Rare Earth Functional Materials (Xiong 'an) Innovation Center Co., Ltd, Hebei (CN); and Grirem (Rongcheng) Co., Ltd., Shandong (CN)
Filed on Apr. 29, 2021, as Appl. No. 17/244,880.
Claims priority of application No. 202010366346.9 (CN), filed on Apr. 30, 2020.
Prior Publication US 2021/0343459 A1, Nov. 4, 2021
Int. Cl. H01F 1/057 (2006.01); H01F 41/02 (2006.01); B22F 3/24 (2006.01); H01F 1/22 (2006.01); H01F 7/02 (2006.01); C22C 38/00 (2006.01); C22C 38/14 (2006.01); C22C 38/06 (2006.01); C22C 38/16 (2006.01); C22C 38/10 (2006.01)
CPC H01F 1/22 (2013.01) [C22C 38/005 (2013.01); C22C 38/06 (2013.01); C22C 38/10 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); H01F 7/02 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A R-T-B sintered magnet, comprising a grain boundary region T1, a shell layer region T2 and an R2Fe14B grain region T3, and the shell layer region T2 is located at the junction of the grain boundary area T1 and the R2Fe14B grain area T3, which covers the R2Fe14B grain area T3 and has a predetermined thickness; wherein
R contains light rare earth LRE and heavy rare earth HRE, and a content proportion of the HRE is 0.05 wt. % to 1.5 wt. %; and
T contains Al and M, and a proportion of Al is 0.22 wt. % to 0.35 wt. %; and M is at least one of Ga, Cu and Zn, and a mass ratio of M/Al is 2 to 3; and
at 10 μm to 60 μm from a surface of the sintered magnet toward a center thereof, an area ratio of the shell layer region T2 to the R2Fe14B grain region T3 is 0.1 to 0.3, and a thickness of the shell layer region T2 is 0.5 μm to 1.2 μm; and an average coating percent of the shell layer region T2 on the R2Fe14B grain region T3 is 80% or more; and
a mass ratio of (HRE+M+Al)/(LRE+T) in the shell layer region T2 is 0.02 to 0.4;
a mass ratio of HRE/(LRE+T) in the shell layer region T2 is greater than a mass ratio of HRE/(LRE+T) in the R2Fe14B grain region T3; and
a mass ratio of Al/(LRE+T) in the shell layer region T2 is greater than a mass ratio of Al/(LRE+T) in the R2Fe14B grain region T3.