Study On The Preparation And Mageticproperties Of Sm₂Fe_17-xNb_xN_y Magnetic Powders

Sm2Fe17Nx is an outstanding coercive permanent magnetic material of rare-earth metallic compound. Its appearance made the magnetic material enter a new era. But it is very difficult to get steady and high quality Sm2Fe17Nx as its properties are sensitive to the parameters of the preparing technology. So this paper is to discuss how to control the processing parameters so as to obtain the optimum microstructure and composition, thus we can get the excellent properties of Sm2Fe17-xNbxNy rare-earth permanent magnetic material.Sm2Fe17-xNbxNy alloys are prepared through HDDR(Hydrogen-Disproportionation-Desorption-Recombination) method. Through using scanning electron microscope with energy-dispersive X-ray analysis, X-ray diffraction technique and vibrating sample magnetometer etc, we can observe the microstructure and measure the magnetic properties of alloys.Through analyzing the phase composition and microstructure of Sm2Fe17-xNbx alloys (x=0.5,1,2,3), we study the influence of the addition of element Nb on the microstructure of Sm2Fe17 alloys . The results show that the as-cast structure of Sm2Fe17-xNbx alloys can be improved effectively. When the atomic ratio of Nb is one, the structure is homogeneous and almost composed of the single Sm2Fe17 phase. It's nearly the same structure as that after annealing. So it can reduce the production cost and increase the stability of magnetic properties. The effect mechanism of Nb is also introduced.Finally we compare the data obtained from diffusion experiments conducted on powders of the Sm2Fe17-xNbx alloys after nitrifing. The powders were nitrifed for 2h, 6h, 9h and 12h respectively. They reveal the behavior of N atom in alloys. By investigating the magnetic properties of Sm2Fe17-xNbxNy magnetic powders with different composition and different nitriding time, the relationship between the magnetic properties and different composition and parameters of the preparation process is summarized. So it can prevent the formation of soft magnetic phase and decomposition of Sm2Fe17-xNbxNy during nitriding.