| The demand for high performance magnetic materials is also increasing with the rapid development of information technology.In this context,it is an important development direction to seek for magneto electronic material devices with high sensitivity,high energy storage density,low power consumption and miniaturization.At present,rare earth-based magneto-electronic materials play an important role in high technology fields such as high performance sensors,advanced permanent magnet motors and maglev trains due to their excellent magnetic properties.There are also different coercivity requirements for rare earth magneto-electronic materials when they are used in different scenarios.For example,sensor components based on magnetostrictive effects want materials with low hysteresis and coercivity to respond quickly to changes in the field.In the field of permanent magnet,strong ferromagnetism can be maintained under various extreme conditions to avoid the performance loss caused by demagnetization when the magnet presents a large coercive force.Therefore,the coercivity of rare earth magneto-electronic materials has become an important research topic.In this paper,the micromagnetic simulation of rare earth magnetostrictive Tb0.3Dy0.7Fe2（Tb-Dy-Fe）and rare earth permanent magnet Ce1.66Mg1.34Co9（Ce-Mg-Co）materials is carried out.The main contents are as follows:（1）Tb-Dy-Fe has been widely used in microcomputer and electrical parts because of its excellent magnetostrictivity at room temperatur.However,the Tb-Dy-Fe based magnetic sensor shows great coercivity and hysteresis,which inevitably limits its application range.In view of this,anα-Fe/Tb-Dy-Fe precipitation model was constructed based on micromagnetic simulation.As the size ofα-Fe in Tb-Dy-Fe increases from 4 nm to 50 nm,the coercivity decreases from 31.46m T to 12.48m T.The declining trend of coercivity can be well fitted to the inverse square relation and fit well to the nucleation field theory.These results are beneficial to the low power consumption and the strict requirements of miniaturization of Tb-Dy-Fe based magnetic sensors.（2）The new rare earth ferromagnetic material Ce-Mg-Co has high Ce abundance and low price.As a permanent magnet material,it can not only balance the utilization of rare earth,but also reduce the application cost.However,the coercivity of Ce-Mg-Co magnet is relatively small and easy to demagnetize,which limits its practical application to some extent.In view of this,a Ce-Mg-Co grain boundary model was constructed based on micromagnetic simulation.When the saturation magnetization in grain boundary decreases from 250 k A/m to 50 k A/m,the coercivity increases from1.05 T to 1.32 T.In addition,with the increase of grain boundary exchange strength,the coercivity of samples on the whole increases slightly and then decreases gradually,showing a weak dependence relationship.These results are beneficial to further optimize the coercivity,magnetic energy product and other macroscopic permanent magnet properties of Ce-Mg-Co alloy. |
