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| The Influence of Dehydrogenation Speed on the Microstructure and Magnetic Properties of Nd-Fe-B Magnets Prepared by HDDR Process |
| Journal of Magnetics, Volume 19, Number 1, 31 Mar 2014, Pages 49-54 |
Hee-Ryoung Cha (Powder & Ceramics Division, Korea Institute of Materials Science), Ji-Hun Yu (Powder & Ceramics Division, Korea Institute of Materials Science), Youn-Kyoung Baek (Powder & Ceramics Division, Korea Institute of Materials Science), Hae-Woong Kwon (Department of Materials Science and Engineering, Pukyong National University), Yang-Do Kim (School of Materials Science and Engineering, Pusan National University), Jung-Goo Lee *  (Powder & Ceramics Division, Korea Institute of Materials Science) |
| Abstract |
The influence regarding the dehydrogenation speed, at the desorption-recombination state during the hydrogenation-disproportionation-desorption-recombination (HDDR) process, on the microstructure and magnetic properties of Nd-Fe-B magnetic powders has been studied. Strip cast Nd-Fe-B-based alloys were subjected to the HDDR process after the homogenization heat treatment. During the desorption-recombination stage, both the pumping speed and time of hydrogen were systematically changed in order to control the speed of the desorption-recombination reaction. The magnetic properties of HDDR powders were improved as the pumping speed of hydrogen at the desorption-recombination stage was decreased. The lower pumping speed resulted in a smaller grain size and higher DoA. The coercivity and the remanence of the 200-300 μm sized HDDR powder increased from 12.7 to 14.6 kOe and from 8.9 to 10.0 kG, respectively. In addition, the remanence was further increased to 11.8 kG by milling the powders down to about 25-90 μm, resulting in (BH)max of 28.8 MGOe.
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| Keywords: grain size; hard magnetic materials; HDDR; Nd-Fe-B; anisotropy |
| DOI: http://dx.doi.org/10.4283/JMAG.2014.19.1.049 |
| Full Text: PDF |
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