The formation mechanism of the nanocrystalline cells in Sm 2 Fe 17 N x powder during overnitridation
| Autor: | Akihide Hosokawa, Kenta Takagi |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Nanostructure Materials science Polymers and Plastics Metals and Alloys 02 engineering and technology Coercivity 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Nanocrystalline material Electronic Optical and Magnetic Materials Amorphous solid Crystallography Magnetization Chemical engineering Magnet 0103 physical sciences Ceramics and Composites Particle 0210 nano-technology |
| Zdroj: | Acta Materialia. 136:366-377 |
| ISSN: | 1359-6454 |
| DOI: | 10.1016/j.actamat.2017.07.019 |
| Popis: | It is known that an overnitridation process significantly improves the coercivity of coarse Sm-(Fe,M)-N magnet powder (M = Cr, Mn, Ti, V) and also introduces a unique microstructure in the particles wherein nanocrystalline cells are separated by amorphous walls (=frequently called nano-cell like structure). It has however been reported that those nanocrystalline cells rotate spontaneously during overnitridation and thus the final powder product becomes unfortunately isotropic. The phenomena have widely been known for more than two decades but the formation/rotation mechanism of the nano-cell like structure is not well understood yet. In this study, the evolutions of the magnetic properties and the microstructure during overnitridation were investigated in greater detail. The multi-scale microstructural observation technique that combines the recent electron microscopic machines disclosed what was occurring in the particles during overnitridation; it was found that the local nitrogen content and the microstructure in a particle are highly heterogeneous and the spontaneous rotation, surprisingly, do not occur. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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