SmFeN, also known as Sm2Fe17N3, has always been expected as a potential option for next generation of permanent magnetic material, thus attracted many attentions since its discovered by Michael Coey in 1990. SmFeN has many advantages, include:
- Its Curie temperature can reach 476 degrees Celsius which much higher than conventional sintered Neodymium magnets.
- Anisotropic field three times as big as Nd2Fe14B and has huge potential to fabricate high coercivity magnets.
- SmFeN did not have to add Cobalt or other heavy rare earth to adjust magnetic properties.
- Superior corrosion and oxidation resistance.
Sm2Fe17N3 phase will decompose into SmN and α-Fe once the temperature exceeds 650 degrees Celsius. Therefore, sintered SmFeN magnets cannot be manufactured via regular sintering technology. Commercialization of SmFeN is firstly realized in bonded magnets area by Japanese companies. Either isotropic magnet or anisotropic magnet need stable raw material. Daido applied rapidly quenched technology to prepare isotropic powder and magnet’s performance even higher than compression molded NdFeB magnets. Both Nichia and Sumitomo used reduction-diffusion technology to obtained anisotropic powder which well suited to injection molded magnets.