Sm(Co,Cu,Fe,Zr)_z反磁化过程的微磁学分析

Micromagnetic analysis of the magnetization reversal processes in Sm(Co,Cu,Fe,Zr)_z magnets

通过微磁学有限元方法研究了微结构对各向异性的Sm(Co ,Cu ,Fe ,Zr) z 磁性能的影响 ,并对不同温度下的退磁曲线进行了计算 .计算结果表明 ,矫顽力随着 2∶17相晶粒尺寸的增大而增大 ,随 1∶5晶界相厚度的增大而减小 ;通过减小晶界相厚度或增大晶粒尺寸可以有效提高磁能积 .反磁化的物理机制主要为形核机制 ,主要表现为首先在晶界相形成反磁化核 ,随着磁场的增大反磁化核不断长大 ,最后导致整个磁体的磁化反转 ;而当温度升高时 ,晶界相逐渐变成非磁性相 ,使得反磁化核难以形成 。

The influence of microstructure on magnetic properties of Sm(Co,Cu,Fe,Zr) z magnets is investigated by micromagnetic finite-element method. The demagnetization curves at different temperatures are also simulated. The calculated results show that the saturation polarization J s depends on the relative proportions of 2∶17 phase and 1∶5 phase. The coercivity and the maximum energy product increase with increasing 2∶17-type cell size,while they decrease with increasing width of 1∶5-type cell boundary. The coercivity analysis shows that the magnetization reversal in Sm(Co,Cu,Fe,Zr) z magnets is mainly controlled by nucleation at cell boundary. The abnormal temperature dependence of coercivity is due to the fact that the cell boundary becomes less magnetic even nonmagnetic and the nucleation is difficult with increasing temperature.