The Effect Of The Preparation And The Parameters Process On Magnetic Properties Of Sm₂Fe₁₇N_x Magnetic Powders

As a new type rare-earth permanent magnetic material, SmaFenNx has excellent magnetic properties . Although progress has been made in the investigation of SniaFenNx rare-earth permanent magnetic material, up to now Sm2Fe17Nx in the experiment has not been attain the theoritical value because it is sensitive to the parameters of process . The purpose for the reseach is to study how to control the parameters of process so as to obtain the optimum microstructure and composition , thus the excellent properties of Sm2Fe17Nx rare-earth permanent magnetic material may be exploited .Using gas-solid phase reaction Sm2Fe17Nx rare-earth permanent magnetic material is prepared. The effects of parameters of process on the magnetic properties during the preparation of Sm2Fe17Nx are investigated. It is analyzed how to control the factors of process to improve the magnetic properties.Firstly the effects of melting parameters on the microstructure of as-cast alloy are discussed, On the base of this, a series of more appropriate process for melting is determined. By analyzing the microstructure of as-cast alloys with different surplus of samarium added, the optimum surplus of samarium is decided. By comparing the microstructure of the alloys annealed for different time, the ideal and economical annealing time is confirmed. The microstructure and phase composition of alloys during the whole preparation of Sm2Fe17Nx are analyzed using the scanning electron micrograph with energy-dispersive X-ray analysis and X-ray diffraction patterns.Secondly, the diffusion process of nitrogen atom in Sm2Fe17 alloy is studied.The relationship between the values for X in Sm2Fe17Nx and nitriding time is analyzed using the energy-dispersive X-ray analysis. It reveals that the values for X in Sm22Fe17Nx will decrease if the nitriding time is too long, in other words, the Sm2Fe17Nx will decompose.At last, the effects of nitriding time and milling time on the magnetic properties of Sm2Fe17Nx are studied detailedly and the dependence of the magnetic properties of Sm2Fe17Nx on the nitriding time and milling time is achieved. At the same time, some important factors affecting the magnetic properties of Sm2Fe17Nx are analyzed.