Structure of the new metastable grain boundary phase in melt-spun Nd15Fe77B8 ribbons and its roles on high coercivity

Eiji Iwamura, Katsuhisa Nagayama, Toshio Suzuki, Takateru Umeda

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3 Citations (Scopus)

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 languageEnglish
Pages (from-to)111-116
Number of pages6
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume54
Issue number1
Publication statusPublished - 1990 Jan
Externally publishedYes

Fingerprint

Coercive force
ribbons
coercivity
Grain boundaries
grain boundaries
Phase boundaries
Nucleation
nucleation
Phase control
phase control
Metastable phases
Electron diffraction
Diffraction patterns
Lattice constants
Magnetic properties
diffraction patterns
electron diffraction
magnetic properties
Heating
heat

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 journalArticle

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