Microstructure analysis of Nd-Fe-B sintered magnets improved by Tb-metal vapour sorption.
Behaviours of constituent elements in the Nd-Fe-B sintered magnets improved by Tb-metal vapour sorption have been investigated by using an analytical transmission microscopy. It was found that a triple junction of the grain boundaries consists of fine Nd-O crystalline and amorphous phase. The energy dispersive X-ray spectroscopy (EDS) analysis showed that the amorphous phase mainly consists of Co, Nd and Tb. The Tb-treatment causes the formation of the amorphous Co-Nd(Tb) wetting-layer phase which wraps each Nd(2)Fe(14)B grain. The results suggest that the wrapped structure prevents the nucleation of magnetic reversed domains and then improves significantly the coercivity of the magnet.
Watanabe
N
N
Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580, Japan. natanan6@asem.kyushu-u.ac.jp
Umemoto
H
H
Ishimaru
M
M
Itakura
M
M
Nishida
M
M
Machida
K
K