Title :
Anisotropic Nd2Fe14B-based magnet powder with high remanence produced by modified HDDR process
Author :
Morimoto, K. ; Nakayama, R. ; Mori, K. ; Igarashi, K. ; Ishii, Y. ; Itakura, Masaru ; Kuwano, N. ; Oki, K.
Author_Institution :
Central Res. Inst., Mitsubishi Mater. Corp., Omiya, Japan
fDate :
9/1/1999 12:00:00 AM
Abstract :
The hydrogenation-decomposition-desorption-recombination (HDDR) process is a unique method to produce anisotropic Nd2Fe14B-based magnet powder for bonded magnet application. In this study, we studied the effect of appending the intermediate Ar (IA) treatment, i.e., hydrogenated materials are annealed under an Ar atmosphere before the evacuation treatment in the HDDR process, on the magnetic properties of magnet powder. It was found that the IA treatment is very effective to enhance magnetic anisotropy of the powder. The optimum magnetic properties of the anisotropic bonded magnet made from the IA treatment processed Nd12.6Febal. Co17.4B6.5Zr0.1Ga0.3 powder are as follows: Br=1.06 T, HcJ=992 kA/m, and (BH)max=193 kJ/m3. It was observed that the IA treatment induces rapid growth of a α-(Fe,Co) grains in the decomposed mixture of the alloy. This microstructural change of the alloy is considered to be strongly related to the preferred crystallographic orientation of the final magnet powder
Keywords :
annealing; boron alloys; crystal microstructure; desorption; ferromagnetic materials; iron alloys; magnetic anisotropy; neodymium alloys; permanent magnets; powder metallurgy; remanence; sorption; α-(Fe,Co) grains; Ar atmosphere; Nd2Fe14B; NdFeCoBZrGa; anisotropic Nd2Fe14B-based magnet powder; annealing; bonded magnet application; evacuation treatment; high remanence; hydrogenation-decomposition-desorption-recombination process; intermediate Ar treatment; magnetic anisotropy; magnetic properties; microstructural change; modified HDDR process; optimum magnetic properties; preferred crystallographic orientation; Anisotropic magnetoresistance; Argon; Bonding; Iron; Magnetic anisotropy; Magnetic materials; Magnetic properties; Neodymium; Perpendicular magnetic anisotropy; Powders;
Journal_Title :
Magnetics, IEEE Transactions on
