Abstract
Microstructures and magnetic properties were studied of melt-spun Nd15Fe77B8 ribbons with various thicknesses. High coercive force up to 1824 kA·m-1 (22.8 kOe) was found for ribbons with 45-100 μm in thickness. Interspaces among Nd2Fe14B grains were filled by a non-magnetic phase. Electron diffraction patterns of the grain boundary phase were analyzed to reveal that this phase is of tetragonal structure with lattice constants of a=0.512 nm an c=0.801 nm. An orientation relationship was found such that [001] of the boundary phase lies parallel to the [001] direction of the host Nd2Fe14B phase. The boundary phase is metastable, since it was decomposed into fcc Nd and a small amount of NdFe4B4 phase on heating above 690 K. Coercive force is discussed in terms of a nucleation controlled coercivity mechanism. The smoothness of the interface between Nd2Fe14B and the boundary phase controls the nucleation behavior of reverse domains. Thus, as-melt spun ribbons exhibited smooth boundaries and high coercive force, heat treated specimens exhibited rough boundaries and low coercive force.
| Original language | English |
|---|---|
| Pages (from-to) | 111-116 |
| Number of pages | 6 |
| Journal | Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals |
| Volume | 54 |
| Issue number | 1 |
| Publication status | Published - 1990 Jan |
| Externally published | Yes |
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ASJC Scopus subject areas
- Metals and Alloys
Cite this
Structure of the new metastable grain boundary phase in melt-spun Nd15Fe77B8 ribbons and its roles on high coercivity. / Iwamura, Eiji; Nagayama, Katsuhisa; Suzuki, Toshio; Umeda, Takateru.
In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, Vol. 54, No. 1, 01.1990, p. 111-116.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Structure of the new metastable grain boundary phase in melt-spun Nd15Fe77B8 ribbons and its roles on high coercivity
AU - Iwamura, Eiji
AU - Nagayama, Katsuhisa
AU - Suzuki, Toshio
AU - Umeda, Takateru
PY - 1990/1
Y1 - 1990/1
N2 - Microstructures and magnetic properties were studied of melt-spun Nd15Fe77B8 ribbons with various thicknesses. High coercive force up to 1824 kA·m-1 (22.8 kOe) was found for ribbons with 45-100 μm in thickness. Interspaces among Nd2Fe14B grains were filled by a non-magnetic phase. Electron diffraction patterns of the grain boundary phase were analyzed to reveal that this phase is of tetragonal structure with lattice constants of a=0.512 nm an c=0.801 nm. An orientation relationship was found such that [001] of the boundary phase lies parallel to the [001] direction of the host Nd2Fe14B phase. The boundary phase is metastable, since it was decomposed into fcc Nd and a small amount of NdFe4B4 phase on heating above 690 K. Coercive force is discussed in terms of a nucleation controlled coercivity mechanism. The smoothness of the interface between Nd2Fe14B and the boundary phase controls the nucleation behavior of reverse domains. Thus, as-melt spun ribbons exhibited smooth boundaries and high coercive force, heat treated specimens exhibited rough boundaries and low coercive force.
AB - Microstructures and magnetic properties were studied of melt-spun Nd15Fe77B8 ribbons with various thicknesses. High coercive force up to 1824 kA·m-1 (22.8 kOe) was found for ribbons with 45-100 μm in thickness. Interspaces among Nd2Fe14B grains were filled by a non-magnetic phase. Electron diffraction patterns of the grain boundary phase were analyzed to reveal that this phase is of tetragonal structure with lattice constants of a=0.512 nm an c=0.801 nm. An orientation relationship was found such that [001] of the boundary phase lies parallel to the [001] direction of the host Nd2Fe14B phase. The boundary phase is metastable, since it was decomposed into fcc Nd and a small amount of NdFe4B4 phase on heating above 690 K. Coercive force is discussed in terms of a nucleation controlled coercivity mechanism. The smoothness of the interface between Nd2Fe14B and the boundary phase controls the nucleation behavior of reverse domains. Thus, as-melt spun ribbons exhibited smooth boundaries and high coercive force, heat treated specimens exhibited rough boundaries and low coercive force.
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M3 - Article
VL - 54
SP - 111
EP - 116
JO - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
JF - Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
SN - 0021-4876
IS - 1
ER -