# Fileset

[abstract.docx](https://mdr.nims.go.jp/filesets/b363a3b0-b328-475a-86fc-d221b76c6bfa/download)

## Creator

[BOLYACHKIN Anton](https://orcid.org/0000-0003-0420-1806), DENGINA Ekaterina, [KULESH Nikita](https://orcid.org/0000-0001-7046-2671), [TANG Xin](https://orcid.org/0000-0001-6762-6145), [SEPEHRI AMIN Hossein](https://orcid.org/0000-0002-7856-7897), [OHKUBO Tadakatsu](https://orcid.org/0000-0003-3548-1951), [HONO Kazuhiro](https://orcid.org/0000-0001-7367-0193)

## Rights

[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Tomography-based Micromagnetic Simulations of Nd-Fe-B Magnets: the Role of Intergranular Phase Nonuniformities](https://mdr.nims.go.jp/datasets/c29d603b-2464-4c65-b021-7b1eaee82da6)

## Fulltext

Guidelines for AbstractTomography-based Micromagnetic Simulations of Nd-Fe-B Magnets:the Role of Intergranular Phase NonuniformitiesAnton Bolyachkin1,2, Ekaterina Dengina1,3, Nikita Kulesh1, Xin Tang1,2,Hossein Sepehri-Amin1,3, Tadakatsu Ohkubo1, and Kazuhiro Hono1,31Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science, Tsukuba, Japan2International Center for Young Scientists, National Institute for Materials Science, Tsukuba, Japan3Graduate School of Science and Technology, University of Tsukuba, Tsukuba, JapanHigh-performance Nd2Fe14B-based permanent magnets are among the key functional materials for green energy technologies such as wind turbines and electric/hybrid vehicles. Although decades of research have pushed the maximum energy product of Nd-Fe-B magnets close to its theoretical limit, the coercivity is still far below its potential [1]. The required coercivity enhancement is strongly related to the fine tuning of the intergranular phase (IGP), i.e., its thickness, magnetic properties and the local variation of both. Other microstructural features such as grain size, crystallographic texture, secondary phases, etc. should also be well controlled.Up-to-date, the contributions of listed microstructural features have been investigated in simplified micromagnetic models under certain assumptions living a room for debate and hindering a quantitative comparison with experimental data [2,3]. In this report, we present a large-scale micromagnetic model of hot-deformed Nd-Fe-B magnets constructed based on a FIB-SEM tomographic data. This model can accurately reproduce the microstructure of real magnets. In particular, the IGP is represented by a set of thin individual regions localized between contacting faces of adjacent platelet-shaped grains. All such IGPs are isolated from each other by triple junctions. Here we performed micromagnetic simulations to study how the variations of both IGP thickness and magnetization, which have been experimentally observed [4], affect the coercivity of the hot-deformed Nd-Fe-B magnets. Also, we will emphasize another important factor for coercivity engineering that is triple junctions. Some relatively thin triple junctions are supposed to be ferromagnetic and can act as nucleation centers for magnetization reversal reducing coercivity.Developed tomography-based micromagnetic model reproduces all major microstructural features of hot-deformed Nd-Fe-B magnets. Such a model can be considered as a digital twin of Nd-Fe-B magnets which can be useful to define the most efficient strategy for further coercivity improvement.References[1] J. Li, H. Sepehri-Amin, T. Sasaki, T. Ohkubo, and K. Hono, Most frequently asked questions about the coercivity of Nd-Fe-B permanent magnets, Sci. Tech. Adv. Mater. 22 (2021) 386-403.[2] J. Li, Lihua Liu, H. Sepehri-Amin, Xin Tang, T. Ohkubo, N. Sakuma, T. Shoji, A. Kato, T. Schrefl, and K. Hono, Coercivity and its thermal stability of Nd-Fe-B hot-deformed magnets enhanced by the eutectic grain boundary diffusion process, Acta Mater. 161 (2018) 171.[3] Y. Wu, K.P. Skokov, L. Schäfer, F. Maccari, A. Aubert, H. Xu, H. Wu, C. Jiang, and O. Gutfleisch, Microstructure, coercivity and thermal stability of nanostructured (Nd,Ce)-(Fe,Co)-B hot-compacted permanent magnets, Acta Mater. 235 (2022) 118062.[4] Xin Tang, H. Sepehri-Amin, T. Ohkubo, K. Hioki, A. Hattori, and K. Hono, Coercivities of hot-deformed magnets processed from amorphous and nanocrystalline precursors, Acta Mater. 123 (2017) 1.