Coercivity and spin reorientation transitions in Nd-Fe-B nanocomposites prepared by melt spinning

Author

Dahlgren, M. ; Kou, X.C. ; Grössinger, R. ; Liu, J.F. ; Ahmad, I. ; Davies, H.A. ; Yamada, Koji

Author_Institution

Inst. fur Exp. Phys., Vienna Univ. of Technol., Austria

Volume

33

Issue

3

fYear

1997

fDate

5/1/1997 12:00:00 AM

Firstpage

2366

Lastpage

2368

Abstract

Alloys of composition Nd₉Fe₈₅B₆, Nd_11.76Fe_82.46B_5.88, and Nd₁₈Fe₇₆B₆ were prepared by melt spinning at roll velocities from 19 to 25 m/s. The grain size distribution of rapidly quenched flakes was evaluated by means of X-ray diffraction line broadening. The average grain size of rapidly quenched Nd-Fe-B alloys is within a range from 19 to 40 nanometers and differs from the roll contact side to the free side of the flakes. For the first time, the spin reorientation transitions T_ST of nanophase Nd ₂Fe₁₄B alloys have been determined. They were found to be lower than that of bulk Nd₂Fe₁₄B. The smaller the grain size, the lower is T_ST. Also for the first time, the temperature dependence of the coercivity of nanophase Nd-Fe-B magnets was determined from 4.2 to 300 K by measuring hysteresis loops on a single flake in a pulsed-field magnetometer with a field strength up to 24 MA/m. The coercivity of the nanophase Nd-Fe-B has less of a temperature dependence than sintered magnets

Keywords

X-ray diffraction; boron alloys; coercive force; ferromagnetic materials; grain size; iron alloys; magnetic anisotropy; magnetic hysteresis; magnetic transitions; melt spinning; nanostructured materials; neodymium alloys; permanent magnets; rapid solidification; spin dynamics; 19 to 25 m/s; 19 to 40 nm; 4.2 to 300 K; Nd-Fe-B nanocomposites; Nd_11.76Fe_82.46B_5.88; Nd₁₈Fe₇₆B₆; Nd₉Fe₈₅B₆; X-ray diffraction line broadening; coercivity; grain size distribution; hysteresis loops; magnetic anisotropy; melt spinning; nanophase Nd-Fe-B magnets; nanophase Nd₂Fe₁₄B alloys; pulsed-field magnetometer; rapidly quenched flakes; roll velocities; spin reorientation transitions; temperature dependence; Coercive force; Grain size; Iron alloys; Magnetic field measurement; Magnets; Neodymium; Pulse measurements; Spinning; Temperature dependence; X-ray diffraction;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.573858

Filename

573858