Magnetic and microstructural modification of the Nd–Fe–B sintered magnet by mixed DyF3/DyHx powder doping

We investigated the magnetic and microstructural properties of Nd–Fe–B sintered magnets doped with DyF3, DyHx, and a mixture of DyF3 and DyHx powders. In the DyHx-doped magnet, diffusion of Dy occurs predominantly via grain boundary diffusion. However, the proportion of Dy being diffused by lattice...

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Bibliographic Details
Published in:Journal of applied physics 2014-05, Vol.115 (17)
Main Authors: Tae-Hoon, Kim, Seong-Rae, Lee, Hyo-Jun, Kim, Min-Woo, Lee, Tae-Suk, Jang
Format: Article
Language:English
Subjects:
Diffusion
Doping
Grain boundaries
Grain boundary diffusion
Magnetic properties
Magnets
Neodymium
Sintering (powder metallurgy)
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Summary:We investigated the magnetic and microstructural properties of Nd–Fe–B sintered magnets doped with DyF3, DyHx, and a mixture of DyF3 and DyHx powders. In the DyHx-doped magnet, diffusion of Dy occurs predominantly via grain boundary diffusion. However, the proportion of Dy being diffused by lattice diffusion is increased in the DyF3-doped magnet due to the different influences of F− and H+ ions. The detailed mechanism of the microstructural changes in terms of the diffusional behavior of Dy induced by the DyF3 and DyHx powder doping is discussed. The formation of a Dy-segregated Nd-rich oxide phase (RE-rich, Dy–Nd–O) was suppressed only in the DyF3-doped magnet, and the (00L) alignment of Nd2Fe14B grains in the sintered magnet increased when it was doped with the DyHx powder. We obtained the optimum microstructural and magnetic properties of the Nd–Fe–B sintered magnet through doping with a mixture of DyF3 and DyHx powders, which compensated for the drawbacks of using each powder alone.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4867965