Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10710333 | Journal of Magnetism and Magnetic Materials | 2019 | 8 Pages |
Abstract
Low melting point Pr-Al-Cu alloys were employed in grain boundary diffusion for sintered NdFeB magnets. The coercivity of the 7â¯Ãâ¯7â¯Ãâ¯2â¯mm magnet was enhanced from 1000â¯kA/m to 1360, 1615, and 1714â¯kA/m by diffusing Pr70Al10Cu20, Pr70Al15Cu15 and Pr70Al20Cu10 alloys, respectively, at 800â¯Â°C for 2â¯h followed by 500â¯Â°C for 3â¯h. The optimized microstructure with strip-like grain boundary phase was evident in diffused magnets, which helps to reduce the magnetic exchange interaction between the hard magnetic grains and improve the coercivity. Under the same diffusion process, the coercivity of the diffused magnets decreased with increasing sample thickness, but 27% coercivity enhancement can still be obtained in the magnet with 6â¯mm in height. A Φ10Ã10â¯mm block magnet was diffused by Pr70Al20Cu10 alloy at 800â¯Â°C for 2-10â¯h. Up to 49% enhancement in coercivity was achieved, which confirms the diffusion ability of Pr-Al-Cu alloy. The diffusion behavior of Pr, Al and Cu elements has been analyzed by Fick's law. Based on the diffusion coefficients obtained at 800 and 900â¯Â°C, Pr diffuses faster than Cu and Al along the grain boundary. The current results demonstrated that Pr-Al-Cu alloys can effectively optimize the grain boundary structure and improve the coercivity of NdFeB magnets.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Huixin Zeng, Zhongwu Liu, Wei Li, Jiasheng Zhang, Lizhong Zhao, Xichun Zhong, Hongya Yu, Baochun Guo,