No abstract

In this work, Cr diffused Sm 2 Fe 17 N x core-shell magnetic powders were prepared by reduction-diffusion (RD) process. Sm 2 Fe 17 coarse, Cr 2 O 3 and Sm 2 O 3 fine powders were pulverized and mixed by ball milling, and the mixed powder was heat treated following Ca addition. Cr can diffuse into Sm 2 Fe 17 powder above 875°C in RD process, and the diffusion distance of Cr increased with increase in RD temperature. Cr diffusion distance into Sm 2 Fe 17 powder was about 1.1-1.2 μm under RD temperature at 875°C for 1.5 h, and the Cr-diffused Sm-Fe core-shell fine powder was obtained. After nitriding and washing, Cr-diffused Sm-Fe-N fine core-shell powder was successfully obtained, and the coercivity and saturation magnetization of the core-shell powder was 855 kA·m −1 and 122 Am 2 ·kg −1 , respectively. The saturation magnetization was higher than non-core-shell Sm-Fe-Cr-N powder.