Nd_7Fe_(61)B_(22)Mo_4Y_6纳米复合永磁材料的磁性能及微结构

The magnetic properties and microstructure of Nd_7Fe_(61)B_(22)Mo_4Y_6 nanocomposite permanent magnetic materials

采用铜模喷注法成功制备了尺寸为1×5×50 mm的长片状Nd_7Fe_(61)B_(22)Mo_4Y_6合金。通过差式扫描量热分析、X射线衍射分析及磁性能测量系统研究了合金的热稳定性、相组成及磁性能。结果表明,合金的磁性能对于热处理条件极为敏感,铸态合金显示软磁性能,经不同温度热处理后,其磁性转变为硬磁特性。通过740℃等温退火10 min,合金表现出最佳磁学性能,其中剩磁0.51 T,矫顽力1289 kA/m,最大磁能积46.2 kJ/m3。Nd_7Fe_(61)B_(22)Mo_4Y_6合金优良的磁性能可以归结为软磁相颗粒α-Fe、Fe3B和硬磁相颗粒Nd2Fe14B之间强烈的交换耦合作用。由于其尺寸大和磁性能良好的特点,Nd-Fe-B-Mo-Y系纳米复合永磁合金具有潜在的应用价值。

The Nd7Fe61B22Mo4Y6 sheet alloys with dimension of 1×5×50 mm have been prepared by copper mold casting technique.The thermal behavior,microstructure and magnetic properties of the magnets have been investigated by differential scanning calorimetry,X-ray diffractometry and magnetometry techniques.The as-cast Nd7Fe61B22Mo4Y6 alloy exhibits soft magnetic properties,which changes into magnetically hard after annealing.Results show that the magnetic properties of the alloy are sensitive to thermal processing conditions.The optimum hard magnetic properties with remanence(Br)of 0.51 T,coercivity(Hci)of 1289 kA/m and maximum energy product(BH)max of 46.2 kJ/m^3 were achieved after annealing the alloy at 740℃ for 10 min.The good magnetic properties of the Nd7Fe61B22Mo4Y6 magnets are ascribed to the exchange coupling between the nano-scaled soft α-Fe,Fe3 B and hard Nd2Fe14B magnetic grains.Large size bulk nanocomposite magnets with sound magnetic properties make the Nd-Fe-B-Mo-Y alloy system a promising candidate for industrial applications.