Origin of Poor Thermal Stability of HDDR-Treated Nd-Fe-B-Type Material

Author

Matin, Md Abdul ; Hae-Woong Kwon ; Jung-Goo Lee ; Ji-Hun Yu

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

Thermal stability of the Nd_12.5Fe_80.6B_6.4Ga_0.3Nb_0.2 hydrogenation, disproportionation, desorption and recombination (HDDR)-treated powder was studied, and it was correlated to the residual hydrogen in the powder. Presence of the residual hydrogen in the HDDR-treated powder was investigated by X-ray diffraction (XRD), thermopiezic analyser (TPA) and hydrogen analysis. The HDDR-treated material contained a significant amount of hydrogen, and it influenced the thermal stability of the material. Coercivity of the HDDR-treated powder was markedly reduced by heating above 600 ^°C, and it was related to the residual hydrogen. The residual hydrogen existed in the form of Nd₂Fe₁₄BHx hydride, and it was disproportionated into α-Fe, Fe₂B and NdH₂ phases at an elevated temperature. The coercivity reduction was attributed to the magnetically soft α-Fe and Fe₂B phases formed by the disproportionation.

Keywords

X-ray diffraction; boron alloys; coercive force; desorption; gallium alloys; heat treatment; hydrogenation; iron alloys; magnetic particles; neodymium alloys; niobium alloys; soft magnetic materials; thermal stability; HDDR-treated powder materials; Nd_12.5Fe_80.6B_6.4Ga_0.3Nb_0.2; TPA; X-ray diffraction; XRD; coercivity reduction; desorption; disproportionation; heating; hydrogenation; magnetic soft phase; residual hydrogen; thermal stability; thermopiezic analyser; Coercive force; Heating; Hydrogen; Iron; Powders; Thermal stability; Coercivity; disproportionation; hydrogenation, disproportionation, desorption and recombination (HDDR); residual hydrogen;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2013.2274796

Filename

6692985