Journal of Magnetics

The Korean Magnetics Society (한국자기학회)
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The Influence of Dehydrogenation Speed on the Microstructure and Magnetic Properties of Nd-Fe-B Magnets Prepared by HDDR Process

  • Cha, Hee-Ryoung (Powder & Ceramics Division, Korea Institute of Materials Science) ;
  • Yu, Ji-Hun (Powder & Ceramics Division, Korea Institute of Materials Science) ;
  • Baek, Youn-Kyoung (Powder & Ceramics Division, Korea Institute of Materials Science) ;
  • Kwon, Hae-Woong (Department of Materials Science and Engineering, Pukyong National University) ;
  • Kim, Yang-Do (School of Materials Science and Engineering, Pusan National University) ;
  • Lee, Jung-Goo (Powder & Ceramics Division, Korea Institute of Materials Science)
  • Received : 2013.05.20
  • Accepted : 2014.01.14
  • Published : 2014.03.31
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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 ${\mu}m$ 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 ${\mu}m$, resulting in $(BH)_{max}$ of 28.8 MGOe.

Keywords

References

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  2. Anisotropic Consolidation Behavior of Isotropic Nd–Fe–B HDDR Powders During Hot-Deformation vol.53, pp.11, 2017, https://doi.org/10.1109/TMAG.2017.2705107
  3. Coercivity Enhancement of Nd-Fe-B HDDR Powder by Grain Boundary Diffusion Process with Rare-Earth Hydride vol.70, pp.5, 2018, https://doi.org/10.1007/s11837-018-2792-5