快淬速度对纳米晶复合Nd_(8.5)Dy_1Fe_(76)Co_5Zr_3B_(6.5)永磁材料磁性能和微观结构的影响

采用熔体快淬和随后的退火处理制备了Nd_(8.5)Dy_1Fe_(76)Co_5Zr_3B_(6.5)纳米晶复合永磁合金,研究了快淬速度对合金磁性能和微观结构的影响。随着快淬速度的增加,合金的磁性能呈现先升高再下降的趋势,当快淬速度为15 m/s时,合金有最佳的磁性能,B_r=0.70 T,H_(cj)=706.05 kA/m,(BH)_(max)=74.54 kJ/m~3。透射电镜的分析结果表明:合金的晶粒分布均匀,晶粒尺寸约为20 nm。三维原子探针的结果显示Zr元素在硬磁相Nd_2Fe_(14)B的晶界处富集,起到了抑制晶粒长大、细化晶粒的作用,从而提高了材料的磁性能。

Effect of Wheel Speed on the Magnetic Properties and Microstructure of Nanocomposite Nd8.5Dy1Fe76Co5Zr3B6.5 Alloy

The effect of wheel speed on the magnetic properties and microstructure of nanocomposite Nd8.5Dy1Fe76Co5Zr3B6.5 alloy which was prepared by melt-spinning followed by annealing was investigated. The results show that the magnetic property and microstructure of the alloy are very dependent on the wheel speed. The remanence (Br), intrinsic coercivity (Hcj) and maximum energy product ((BH)max) increase with increasing wheel speed, reach their maximum values at 15 m/s and then decrease with further increasing wheel speed. The optimum magnetic property is Br=0.70 T, Hcj=706.05 kA/m, and (BH)max=74.54 kJ/m3. Transmission electron microscope observation reveals a fine and homogeneous microstructure with an average grain size of 20 nm for optimal annealed Nd8.5Dy1Fe76Co5Zr3B6.5 alloy at a wheel speed of 15 m/s. The result of three-dimensional atom probe (3DAP) shows that Zr atoms are enriched in the grain boundary of hard magnetic Nd2Fe14B phase, which may play a role as a crystal growth inhibitor resulting in a fine microstructure, and hence enhance the magnetic property of nanocomposite Nd8.5Dy1Fe76Co5Zr3B6.5 alloy.