Optimization of the post-sintering annealing condition for the high Cu content Nd-Fe-B sintered magnet

We investigated the changes in microstructure and magnetic properties of Nd–Fe–B magnets as a function of Cu content (Cu addition in the range of 0.2–0.5 at. %). We have focused on the phase-transformation temperature of the Nd-rich phases in dependence of the Cu content. The coercivity of the magne...

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Bibliographic Details
Published in:Journal of applied physics 2014-05, Vol.115 (17)
Main Authors: Kim, Tae-Hoon, Lee, Seong-Rae, Woo Kim, Jin, Do Kim, Young, Kim, Hyo-Jun, Lee, Min-Woo, Jang, Tae-Suk
Format: Article
Language:English
Subjects:
Annealing
Coercivity
Copper
Dependence
Grain boundaries
Magnetic properties
Magnets
Neodymium
Phase transitions
Sintering
Transformation temperature
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Summary:We investigated the changes in microstructure and magnetic properties of Nd–Fe–B magnets as a function of Cu content (Cu addition in the range of 0.2–0.5 at. %). We have focused on the phase-transformation temperature of the Nd-rich phases in dependence of the Cu content. The coercivity of the magnets decreased (from 28.7 kOe to 27.1 kOe) on increasing Cu content under identical post-sintering annealing (PSA) conditions. The Cu-enriched C-Nd2O3 triple junction phase (TJP) and grain boundary phase (GBP) were observed in the 0.2 at. % Cu-containing magnet. However, in the 0.5 at. % Cu-containing magnet, the Cu-enriched TJP and GBP appeared in the form of the h-Nd2O3 phase that could be transformed into the C-Nd2O3 phase by a modified 1st-PSA temperature. The coercivity of the 0.5 at. % Cu-containing magnet was noticeably enhanced (from 27.1 kOe to 29.4 kOe).
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4869157