Basic Research On Mechanism Of Reaction Between Nitrogen And Smfe Alloy

Sm2Fe17Nx permanent magnetic material is one of important functional materials in modern society,which contains excellent magnetic property and thermal stability.It is commonly used in the high temperature field,such as drive and engine of electric cars and so on.The Sm Fe alloy nitridation technology has become the core technology for obtaining high-performance Sm2Fe17 Nx alloy.At present,the nitridation process is the solid state nitridation of Sm Fe alloy powder particles.Its uneven nitridation,low efficiency and other shortcomings limit application development.Nitridation of Sm Fe alloy under liquid state and the evolution of Sm Fe N in the process of nitridation are one of the research fields of alloy nitridation.Sm Fe alloy liquid nitridation experiment and solid-state nitridation combined method are mainly used.Therefore,the mechanism of the interaction between nitrogen and Sm Fe alloy is proposed: the interaction of nitrogen and liquid Sm Fe alloy is explored through changing the factors such as pressure,nitridation time and cooling conditions;Meanwhile,the change of the morphology of the solid Sm Fe alloy is observed under the high temperature microscope.The microstructure and phase structure of Sm Fe alloy are analyzed by means of oxygen and nitrogen hydrogen analyzer,SEM,EDS and XRD,and the existence condition of nitrogen in Sm2Fe17 Nx alloy is studied.The experimental study on the liquid nitridation of Sm Fe alloy shows that the argon atmosphere was more suitable for the smelting of Sm Fe alloy than the nitrogen atmosphere;the surface is clean after the solidification of the sample in argon atmosphere.Under the same melting atmosphere,the smaller Sm Fe alloy particles are,the better the melting effect is and the more volatilization of samarium is.Nitridation flow of Sm Fe alloy has remarkable effect on the nitrogen content.Liquid nitrogen content in Sm Fe alloy increases with the increasing of the nitridation flow.When the nutridation flow is 60 m L/min,the percent of nitrogen content in the alloy is 1.88%;The nitrogen content increases and then decreases with time,and the nitrogen content at 8min is 2.03%,that is,the nitrogen content in the alloy increases with the increasing of time within a certain range.Shorter cooling time can obtain higher nitrogen content,reducing the generation of Sm N and α-Fe phase.The casting method is used to cool the Sm2Fe17 Nx alloy,which is composed of Sm2Fe17 Nx phase,Sm-rich phase and a very small amount of α-Fe phase,while no Sm N phase.SmFe alloy solid nitridation experimental study shows that: there are migration behaviors in the boundary of Sm Fe alloy phase with the temperature increasing.When the temperature is 1050 ℃,there appears white Sm-rich phase;At the same temperature,the nitrogen content in alloy increases with the increasing of nitrogen gas flow rate.When temperature is 480 ℃ and nitridation flow is 20 m L/min,the percent of the nitrogen content in the alloy is 0.58%.At low temperature,the nitridation of the solid Sm Fe alloy was not complete,and the diffraction peak corresponding to the Sm2Fe17 Nx phase in the X-ray diffraction spectrum is divided and the nitrogen is not homogeneous.The nitrogen content of Sm2Fe17 Nx alloy is few,more Sm N and ɑ-Fe phase exist in the sample,solid nitridation effect is not ideal.