Study On Preparation And Magnetic Properties Of Sm₂Fe₁₇N_x Fine Powders

The Sm2Fe17Nx compound has excellent intrinsic magnetic properties, which may be a new kind of iron based rare earth permanent magnet materials with the most abundant potentiality in future development following Nd-Fe-B permanent magnet, the third generation rare earth permanent magnet materials. However, it is difficult to obtain steady and high quality Sm2Fe17Nx permanent magnet as its properties are sensitive to the parameters of preparation technology, so there is still a long way to realize the industrial production of Sm2Fe17Nx permanent magnet.How to prepare Sm2Fe17 alloy consisting of single phase is the preliminary problem to get high quality Sm2Fe17Nx permanent magnet, so the first task is to conquer this challenge in this work. This paper focused on the influence of the annealing temperature for homogenization treatment and cooling mode after annealing on Sm2Fe17 alloy structure, and X-ray diffraction, scanning electronic microscope and energy disperse spectroscopy were used to analysis the phase and micro structure of Sm2Fe17 alloy to obtain the optimum experiment conditions. Besides the effect of nitriding time and ball-milling time after nitrogenation on the magnetic properties of alloy powder were investigated and the changes of the phase composition and lattice constant were analyzed by using X-ray diffraction with Jade 5.0 X-ray analysis software combined with the standard PDF card base. Moreover this paper also analysised the particle size distribution of the Sm-Fe alloy powder at different ball-milline time after nitrogenation utilizing laser particle size analyzer. And then the vibrating sample magnetometer was used to detect the magnetic properties of the different particle size distribution of the alloy particles.Finally, this paper gets optimal technological conditions as follow. Homogenization annealing for the Sm-Fe alloy is at 1000℃ for 3 hours under argon atmosphere, and aiming to that the average particle size of Sm-Fe alloy powder is 19.89 Jim, the best nitriding time is 6 hours at 480℃ under 1 atm nitrogen. After treated with nitrogenization at 480℃ for 5 hours, the alloy was carried out ball-milling for different time. And then the optimum particle size is 4.29 μm corresponding that the best ball-milling time is for 6 hours.