20.500.12556/DiRROS-21793 Microstructure refinement of Nd-Fe-B permanent magnets prepared via spark-plasma sintering Sintered Nd-Fe-B-type permanent magnets are normally manufactured using a conventional powder-metallurgy approach. The limitations of such high-temperature, pressureless sintering methods include restricted control over the microstructure due to grain growth and constraints on the magnet’s geometry. The modern spark-plasma sintering (SPS) technique employs Joule heating and external pressure to offer lower consolidation temperatures and faster heating cycles compared to conventional approaches. As a result, the SPS has the potential for the rapid, low-temperature, net-shape manufacture of magnets. However, the nonequilibrium conditions associated with the SPS can lead to poor grain-boundary wetting and the formation of the soft-magnetic α-iron phase in samples prepared from anisotropic, microcrystalline Nd-Fe-B powders produced by standard procedures, i.e., strip casting, hydrogen decrepitation, and jet-milling. This study revealed that the absence of the Nd-rich grain-boundary film is related to the presence of hydrogen. Degassing the Nd-Fe-B powder before applying the SPS improved the distribution of the grain-boundary phase. Moreover, reducing the electrical currents in the sample during the SPS prevented the decomposition of the RE2Fe14B matrix, ensuring a favorable phase composition. Compared to magnets conventionally sintered at 1070 °C, the mean grain diameter of the SPS samples prepared at ≈880 °C was reduced by ≈33%. This reduction decreased the temperature coefficient of coercivity from -0.65 to -0.58%/°C. The coercivity increase measured for the SPS samples amounted to more than 15%, which was attributed to the combined effect of smaller grain size and reduced texture. spark-plasma sintering microstructure refinement sintranje true false true IEEE ZDA Angleški jezik Slovenski jezik © 2024 The Authors. Neznano 2025-03-28 13:32:41 2025-03-28 13:32:42 2025-10-24 03:49:51 0000-00-00 00:00:00 2024 0 0 Nasl. z nasl. zaslona; Opis vira z dne 27. 6. 2024; str. [1-6] iss. 8, article no. 2100406 Vol. 60 Aug. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2024-02-28 2024-06-18 2024-07-26 537 1941-0069 10.1109/TMAG.2024.3417611 199982339 https://ieeexplore.ieee.org/document/10568241 1 bfdfed61-0bd0-11f0-963a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=31410 RAZ_Tomse_Tomaz_2024.pdf RAZ_Tomse_Tomaz_2024.pdf 1 1ED5D705822B48505CCF58ED1E66EB4A 9f3b6dc76677d497909145ffb4da4ff4278471089de289bf2e43068ae1a66131 4d8e47d7-0bd3-11f0-963a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=31413 Institut Jožef Stefan 0 0 0