Preparation of isotropic Sm2Fe17Nx magnetic powders and bonded magnets

The isotropic Sm2Fe17Nx magnetic powders were prepared by Hydrogenation Disproportion Desorption Recombinnation (HDDR) process. The evolutionary processes of phase and microstructure were investigated for Sm-Fe alloy during the solidification, homogenization, HDDR and nitration processes by means of XRD, SEM and EDX The results show that the homogeneous Sm2Fe17 alloy is successfully obtained and the impurity phases and residual stress are well removed after heated at 1050 degrees C for 24 h. When heated at 800 degrees C for 1 h in the atmosphere of hydrogenation with the pressure of 6.1 MPa, the alloy turns into SmHx and the alpha-Fe in nano-scale, and then recombines into Sm2Fe17 crystal after evacuated at the same temperature for 2 h again. The lattice constant of the alloy increases, and the crystal cell expands 6.28% after nitrified at 500 degrees C for 5 h, then the isotropic Sm2Fe17Nx magnetic powders are obtained. The isotropic bonded Sm2Fe17Nx magnets with a density of 0.04 g/cm(3) and Br=0.6704 T, H-cj=1015 kA/m, (BH)(max)=73.7 kJ/m(3) are prepared with the above magnetic powders and epoxy-resin of 3wt% as bonder.