Research On Volatilization Mechanism Of Sm In The Process Of Smelting Smfe Alloy

Alloys with permanent magnetic properties made of transition metals and rare earth metals are called rare earth permanent magnetic materials,which are widely used in mechanical,electronic,instrumentation and medical fields.The fourth generation permanent magnetic material Sm₂F e₁₇N_x has the same intrinsic magnetic properties as Nd₂Fe₁₄B and excellent characteristics like high Curie temperature and good thermal stability.The homogeneous stability of Sm₂Fe₁₇phase has a great influence on the final magnetic prop erties of Sm-Fe-N permanent magnets.Sm is easy to volatilize during the melting process and it is difficult to control the terminal component.Normally,The Sm-Fe alloy consists of Sm₂Fe₁₇ phase and a small amount ofα-Fe and Sm-rich phase.Too much Sm-rich phase andα-Fe soft magnetic phase will affect the final properties of the alloy.At present,there is no systematic study on the melting conditions of samarium ferroalloy,and the melting mechanism of samarium ferroalloy has not been improved.The effect of smelting conditions on the composition and phase composition of Sm-Fe alloy was analyzed by smelting experiments of Sm-Fe alloy.Use TG-DTA equipment,vertical tube furnace,vacuum induction furnace for experiments.By changing the heating rate,heat preservation power,heat preservation time,heat preservation power,melting pressure and other factors,to determine the best melting conditions.The addition of that alloy element uniformizes the composition of the alloy phase.The samarium content,phase composition and microstructure of samarium ferroalloy before and after melting were analyzed by means of ICP-OES,SEM and XRD.The evolution behavior of samarium ferroalloy at variable temperature was obtained,the compensating amount of samarium was determined,and the optimum melting mechanism was established.The optimum melting mechanism of samarium ferroalloy is as follows:three samarium ferroalloy blocks with about 24%samarium content in volume of 1cm3 are selected for smelting,with a total mass of 40g.The pure samarium with 2%purity>99.99%was added to compensate burn loss.Place pure samarium at the bottom of the quartz tube and the samarium ferroalloy at the top.Vacuum induction furnace is used for smelting,and the induction furnace is vacuum pumped to 6.67×10^-3M Pa before melting.The chamber pressure is-0.025 M Pa.When the sample is boiling,1 min is heated for 60 s.After that,the induction furnace power supply is closed and the sample is cooled with the furnace.After cooling,the sample is removed and the impurity layer on the surface of the sample is polished.After grinding the alloy sample into the test tube to repeat the previous smelting process.The sample was melted three times.Figure 42;Table 12;Reference 59.