Abstract
Results of a systematic study concerned with the high-magnetic-field effects on the coercivity in processing various series of sintered Nd-Fe-B magnets are given. Coercivity enhancement phenomenon was observed in several series of sintered Nd-Fe-B magnets with Cu additive after annealing under magnetic fields of 10~14 T. A strong correlation was suggested between the field annealing temperature at which maximum coercivity increase was observed and the anomaly temperature in differential scanning calorimetry experiments. We found a linear relation between the room temperature coercivity H c of the sample annealed at T a=500°C under magnetic field H a for a series of samples with different Dy contents, which can be expressed as H c = H c(0) + αH a, with H c(0) being the value for the zero-field-annealed sample and α, the coercivity enhancement factor. Although very small, α has a positive finite value in samples with 0 mass% and 2 mass% Dy. Significant increase in α value was confirmed for samples with Dy content larger than 6 mass%\ This suggests the effects of higher anisotropy in paramagnetic susceptibility of Nd-rich intergranular phase containing Dy. Also introduced is the preliminary results of the grain boundary diffusion process of sinterd Nd- Fe-B samples with surface Dy layer under strong gradient magnetic fields produced by the 18 T superconducting magnets.
Original language | English |
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Pages (from-to) | 72-80 |
Number of pages | 9 |
Journal | Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals |
Volume | 76 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2012 Jan |
Keywords
- Coercivity
- High-magnetic-field processing
- Sintered neodymium-iron-boron magnet
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys
- Materials Chemistry