Most frequently asked questions about the coercivity of Nd-Fe-B permanent magnets
| Autor: | Hossein Sepehri-Amin, Jiangnan Li, Taisuke Sasaki, Kazuhiro Hono, Tadakatsu Ohkubo |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Permanent magnets microstructure Mathematics::Analysis of PDEs Nd-Fe-B magnets 02 engineering and technology 010402 general chemistry 01 natural sciences Industrial and Manufacturing Engineering thermal stability Mathematics::Numerical Analysis Condensed Matter::Materials Science micromagnetic simulations Condensed Matter::Superconductivity Materials Chemistry General Materials Science coercivity Anisotropy Materials of engineering and construction. Mechanics of materials Condensed matter physics Mechanical Engineering Frequently asked questions Focus Issue on Science and Technology of Element-Strategic Permanent Magnets Metals and Alloys 50 Energy Materials Coercivity 021001 nanoscience & nanotechnology Microstructure 0104 chemical sciences Ferromagnetism Magnet TA401-492 Condensed Matter::Strongly Correlated Electrons Crystallite 0210 nano-technology 203 Magnetics / Spintronics / Superconductors TP248.13-248.65 Biotechnology Research Article |
| Zdroj: | Science and Technology of Advanced Materials article-version (VoR) Version of Record Science and Technology of Advanced Materials, Vol 22, Iss 1, Pp 386-403 (2021) |
| ISSN: | 1878-5514 1468-6996 |
| Popis: | Physically, the coercivity of permanent magnets should scale with the anisotropy field of ferromagnetic compounds, HA; however, the typical coercivity values of commercial polycrystalline sintered magnets are only ~0.2 HA, which is known as Brown’s paradox. Recent advances in multi-scale microstructure characterizations using focused ion beam scanning electron microscope (FIB/SEM), aberration corrected scanning transmission electron microscopy (Cs-corrected STEM), and atom probe tomography (APT) revealed detailed microstructural features of commercial and experimental Nd-Fe-B magnets. These investigations suggest the magnetism of a thin layer formed along grain boundaries (intergranular phase) is a critical factor that influences the coercivity of polycrystalline magnets. To determine the magnetism of the thin intergranular phase, soft X-ray magnetic circular dichroism and electron holography play critical roles. Large-scale micromagnetic simulations using the models that are close to real microstructure incorporating the recent microstructure characterization results gave insights on how the coercivity and its thermal stability is influenced by the microstructures. Based on these new findings, coercivity of Nd-Fe-B magnets is being improved to its limit. This review replies to the most frequently asked questions about the coercivity of Nd-Fe-B permanent magnets based on our recent studies. Graphical abstract |
| Databáze: | OpenAIRE |
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