Controlled Preparation And Magnetic Properties Of SmCoFe And SmFeN Nanocrystalline Permanent Magnet Powders

Nanocrystalline SmCo/Fe dual-phase composite materials and SmFeN single-phase materials have received extensive attention due to their ultra-high theoretical magnetic energy product and high Curie temperature.However,due to the lack of adequate microstructure control,the magnetic properties of these materials are not In view of this,this article takes SmCo/Fe dual-phase composite materials and SmFeN single-phase materials as the research objects,and carries out the control preparation and magnetic properties of SmCo/Fe and SmFeN permanent magnetic powders under high energy ball milling.Research indicates,(1)The raw materials of SmCo₃,SmCo₄and SmCo₅ingots were analyzed by XRD and VSM,and SmCo₅ingots were selected as the next phase.(2)The effects of ball milling strength and ball milling time on the magnetic properties of SmCo₅+25wt%Fe were investigated.It was found that for SmCo₅+25wt%Fe nanocomposite powder,when the milling strength was 25:1,the magnetic energy product of the sample reached the maximum value,and the maximum magnetic energy product reached 167kj/m³.However,the milling time also has a strong influence on the magnetic properties.It is found that the composite powder has the best magnetic properties after 3h high-energy milling.(3)The effects of different annealing temperatures on the magnetic properties of SmCo₅+20%Fe,22.5%Fe,25%Fe,27.5%Fe and 30%Fe powders were investigated and found The maximum magnetic energy product of the composite magnetic powder increases first and then decreases with the increase of annealing temperature,and the best magnetism is obtained at 550?.It is that for high-iron composite magnets with an iron content greater than or equal to 27.5,the coercive force will have a downward trend at 600?.This is due to the obvious phase transition of the 600°C annealed composite powder at this temperature.At the same time,comparing the magnetic properties of SmCo₅/Fe composite powders with different iron contents after crystallization annealing at 550?,it was found that the increase in iron content increased the saturation magnetization and residual magnetization of the sample,but also reduced the coercivity of the sample.It shows that SmCo₅and 27.5wt%Fe nanocomposite have the best comprehensive magnetic properties,and the maximum magnetic energy product can reach 179.8k J/m3.(4)For SmCo_x(x=3,3.5,4,4.5and5)+27.5wt%Fe nanocomposite powder with high iron content,the maximum magnetic energy product is obtained at x=5.XRD analysis shows that the main phase is mainly composed of smco3 after annealing at 550?,but there is no obvious change in the composition at the same temperature.On the contrary,when the crystallization annealing temperature is increased to 600?,the main phase is transformed from SmCo₃to SmCo₅,and the main phase is changed obviously,which shows that the phase transformation is mainly related to the annealing temperature.(5)Compared with room temperature,Sm₂Fe₁₇N_xnanosheets prepared in low temperature environment have more uniform grain diameter,higher room temperature coercive force(1034.8KA/m at300k),and higher residual magnetic ratio(M_r/M_s)And better magnetic orientation.The low temperature environment can effectively absorb the excess energy released during the ball milling process,suppress the decomposition of the Sm₂Fe₁₇N_xphase,and ensure its good crystallinity.