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
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1990
Y1 - 1990
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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U2 - 10.2320/jinstmet1952.54.1_111
DO - 10.2320/jinstmet1952.54.1_111
M3 - Article
AN - SCOPUS:0025248353
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 -