Formation mechanism of Tb-rich shell in grain boundary diffusion processed Nd-Fe-B sintered magnets

SCRIPTA MATERIALIA

卷:178

Article

Kim, Tae-Hoon¹  Sasaki, T. T.¹  Koyama, T.²  Fujikawa, Y.³  Miwa, M.³  Enokido, Y.³  Ohkubo, T.¹  Hono, K.¹ 

[1] Natl Inst Mat Sci, Ctr Magnet Mat, Elements Strategy Initiat, Tsukuba, Ibaraki 3050047, Japan

[2] Nagoya Univ, Dept Mat Design Innovat Engn, Chikusa Ku, Furo Cho, Nagoya, Aichi 4648603, Japan

[3] TDK Corp, Mat Dev Ctr, 570-2 Matsugashita, Minamihadori, Narita 2688588, Japan

关键词: Permanent magnet;    Nd-Fe-B;    Coercivity;    Grain boundary diffusion;    Rare earth;   

DOI  :  10.1016/j.scriptamat.2019.12.002

来源: Elsevier

【 摘 要 】

We propose a new mechanism for the formation of Tb-rich shell in the Nd-Fe-B sintered magnet that was subjected to the grain boundary diffusion (GBD) process using TbH2. Tb-enriched liquid films form along grain boundaries during the GBD process, which migrate by chemically induced liquid film migration (CILFM) to form Tb-rich shells behind. As a result, the Tb-rich shell form asymmetrically along a grain boundary with an abrupt concentration change at a core/shell interface with a gradual decrease of Tb concentration toward a grain boundary. These microstructure features can be reproduced with phase-field simulations. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

Free