Development Trend of Hydrogen-based Technique for Nd-Fe-B Permanent Magnets

The demand for Nd-Fe-B permanent magnets is rapidly increasing as a most important material for traction motors of hybrid/ electric vehicles along with the growth of the eco-friendly mobility field due to industrial changes. However, the issues on the price of heavy rare-earth (HRE) elements, added to improve the thermal stability of the magnet, are constantly arising. To manufacture high-performance magnets by reducing the amount of HRE or Nd, it is important to refine the grain size of the Nd2Fe14B phase (similar to 300 nm). Hydrogen-based technologies such as hydrogenation-Decrepitation and the Hydrogenation-Disproportionation-DesorptionRecombination (HDDR) process are essential for obtaining fine anisotropic powders in manufacturing of sintered and bonded magnets. Furthermore, it can also be applied to the recycling of Nd-Fe-B waste magnets to address future rare-earth resource issues. Herein, we introduce the trend in research and development of the hydrogen-based technology for Nd-Fe-B rare-earth permanent magnets.