Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1798678 | Journal of Magnetism and Magnetic Materials | 2015 | 6 Pages |
Abstract
The electric-current sintering technique was used to fully densify hydrogenation-disproportionation-desorption-recombination (HDDR)-processed Nd-Fe-B powder at temperatures below the grain growth temperature in order to produce high-coercive bulk magnets. However, the sintered magnets exhibited anomalous coercivity reduction that depended on sintered density. Reheating examination of the sintered magnets revealed that the reduced coercivity was increased in proportion to the heating temperature, resulting in complete recovery of coercivity. As a result, the combination of electric-current sintering and post-annealing produced sintered magnets with a coercivity of 15Â kOe. Scanning and transmission electron microscopy revealed no evidence that associated the anomalous coercivity reduction and recovery with grain boundary morphology. On the other hand, various HDDR powders with different particle sizes were sintered, and finer powders yielded lower coercivity after sintering, implying that the anomalous coercivity reduction was associated with particle surface oxides of the raw powder.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
Kenta Takagi, Misaho Akada, Rikio Soda, Kimihiro Ozaki,