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The optimization of grain boundary structure in sintered NdFeCoB magnets was studied using the grain boundary diffusion process (GBDP) with Dy70Al20Cu10 alloy flakes as the diffusion source. These flakes were attached to magnets with a nominal composition of Pr7.8Nd23.4Co12FebalAl0.3Cu0.2Zr0.1B1. Magnets with various coating thicknesses were labeled as follows: GBD-0 (0 mm), GBD-1 (0.03 mm), GBD-2 (0.09 mm), and GBD-3 (0.15 mm). Among them, GBD-3 exhibited optimal performance, increasing the coercivity from 7.94 to 17.63 kOe, which represented a significant enhancement of 122%. And the diffused magnet exhibited a more optimized temperature coefficient. Prior to GBDP, Co aggregated at grain boundaries with Nd2Co17 phase. After GBDP, microstructural analysis revealed the formation of Dy-rich shells with high anisotropy fields around the 2-14-1 phase within the magnet. Additionally, Al and Cu were uniformly distributed, which reduced Nd2Co17 content and enhanced coercivity. This study shows GBDP with " Heavy Rare Earth-Low Melting Point" alloys improves NdFeCoB magnets' magnetic properties, offering a theoretical basis for high-performance, temperature-stable sintered NdFeCoB magnets.

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• Creative Commons BY Attribution 4.0 International
  

Keyword: REPM2025, Grain Boundary Diffusion, NdFeCoB Magnet, Nd2Co17, Coercivity, Low melting-point alloy

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Publisher: National Institute for Materials Science (NIMS)

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Conference: REPM2025 (2025-07-27 - 2025-07-31)

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Manuscript type: Not a journal article

MDR DOI: https://doi.org/10.48505/nims.5665

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Updated at: 2025-09-11 16:30:41 +0900

Published on MDR: 2025-09-11 16:20:03 +0900