Preparation, Structure And Magnetic Properties Of Sm₂Fe₁₇N_x/Fe₃Pt Nanocomposites

High saturation magnetization of Fe₃Pt makes it to be a excellent soft phase. In this paper,α-Fe/Sm₂Fe₁₇N_x/Fe₃Pt diphase nanocrystalline magnets were prepared with different content of Fe₃Pt added by melt-spun and HD (Hydrogenation Decrepitation) treatment. X-ray diffraction, scanning electronic microscope and vibrating-sample magnetometer were used to analysis the processing parameters, microstructure and magnetic properties.The master alloys were composed of four phases,α-Fe, Sm₂Fe₁₇, Fe₃Pt and some SmFe₂ phase. Nanocrystalline ribbons were formed at a speed of 12m/s, and SmFe₂ phase was extinct, the thickness of the ribbons were approximate 70μm. Grains of roll surface were fine and homogeneous, that ensured effective exchange coupling between the soft and hard phases. After melt-spun, large quantity ofα-Fe was generated in Sm_9.7Fe_88.4Pt_1.9 alloy.The two alloys retained the composition of the master alloy after HD treatment. HD treatment had an excellent pulverizing effect and the process was easy to be carried out.The effect of different temperature for nitrogen treatment on structure and magnetic properties were studied. Processing temperature had no effect to the shape of the hysteresis loop. Saturation magnetizations of the two alloys nitrided at 550℃were higher. +Nitrides were finest and well-proportioned when nitriding at 500℃, and Sm_10.2Fe_88.9Pt_0.9 alloy exhibited the hightest coercive force, H_ci=2616.4 Oe. Sm_10.2Fe_88.9Pt_0.9 alloy nitrided at 550℃got the highest magnetic properties, H_ci=2019.7 Oe, M_s=142.6 emu/g, M_r=64.1 emu/g. The non- uniform of the size of the particles and large quantity ofα-Fe contained in the Sm_9.7Fe_88.4Pt_1.9 alloy were the main cause to lead to low magnetic properties.