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The grain boundary diffusion process (GBDP) is one of the most efficient treatments for increasing the coercivity (Hc) of Nd-Fe-B magnets. However, this enhancement typically occurs at the expense of remanence (Mr). In this study, micromagnetic simulations were performed to quantify this tradeoff in hot-deformed Nd-Fe-B magnets subjected to the GBDP using a Nd-based eutectic alloy. The GBDP was imitated in a series of models with a gradually increasing volume fraction of the infiltrated Nd-rich nonmagnetic phase. This infiltration reduced the remanence and grain connectivity via the remaining thin magnetic intergranular phase (IGP), which in turn increased the coercivity. We distinguished between the roles of exchange and magnetostatic interactions in this coercivity enhancement. Furthermore, the simulated Mr vs. Hc curves defined realistic limits for coercivity that depended on the IGP magnetization, which was estimated to be 0.9 ± 0.1 T by reproducing experimental Mr vs. Hc data from the literature.

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Keyword: Micromagnetic simulation , Permanent magnet, Nd-Fe-B, Grain boundary diffusion process

Date published: 2024-03-30

Publisher: Elsevier BV

Journal:

• Scripta Materialia (ISSN: 13596462) vol. 247 116095

Funding:

• Japan Society for the Promotion of Science
• Government of Japan Ministry of Education Culture Sports Science and Technology

Manuscript type: Author's original (Submitted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4676

First published URL: https://doi.org/10.1016/j.scriptamat.2024.116095

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Updated at: 2024-08-23 12:30:14 +0900

Published on MDR: 2024-08-23 12:30:14 +0900