Coercivity of Nd-Fe-B-Type Fine Particles Prepared by Mechanical Milling of HDDR Material

Author

Kwon, H.W. ; Lee, J.G. ; Yu, J.H.

Author_Institution

Dept. of Mater. Sci. & Eng., Pukyong Nat. Univ., Busan, South Korea

Volume

50

Issue

1

fYear

2014

fDate

Jan. 2014

Firstpage

1

Lastpage

4

Abstract

For bonded micro-magnet application, fine particles with high permanent magnetic performance are required. As the HDDR-treated Nd-Fe-B-type material consists of very fine grains (~0.3 μm), the fine particles prepared from the HDDR-treated material are expected to have high magnetic performance even in the form of fine particles. Fine Nd-Fe-B-type particles were prepared by mechanical milling of the HDDR-treated Nd_12.5Fe_80.6B_6.4Ga_0.3Nb_0.2 material, and coercivity of the fine particle was investigated. Coercivity of the HDDR-treated Nd-Fe-B-type material was radically reduced by mechanical milling. Surface oxidation was the major contributory factor for the radical coercivity reduction. Chemical etching of the oxidized surface led to significant recovery of the coercivity. Unlike the mechanically milled fine particles of sintered Nd-Fe-B-type magnet, which lose coercivity almost completely, the moderately milled and etched fine particles (20-80 μm) of HDDR-treated Nd-Fe-B-type material exhibited high coercivity over 12 kOe.

Keywords

boron alloys; coercive force; etching; gallium alloys; iron alloys; micromagnetics; milling; neodymium alloys; niobium alloys; oxidation; permanent magnets; sintering; HDDR material; Nd_12.5Fe_80.6B_6.4Ga_0.3Nb_0.2; bonded micro-magnet application; chemical etching; coercivity; fine particles; mechanical milling; permanent magnetic performance; sintered magnet; size 20 mum to 80 mum; surface oxidation; Coercive force; Materials; Milling; Perpendicular magnetic anisotropy; Surface morphology; Surface treatment; Chemical etching; HDDR-treated Nd-Fe-B; coercivity; mechanical milling; surface oxidation;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2013.2278395

Filename

6692983