Effects of Dy on Magnetic Properties and Microstructure of Nanocomposite (Nd,Pr)10.5-xDyxFe83.5B6 Alloys

采用快淬法制备了镨基(Nd,Pr)10.5-xDyxFe83.5B6 (x=0.0, 0.5, 1.0, 1.5, 2.0, 2.5)系列粘结磁体，研究了Dy元素添加对快淬合金显微组织结构、磁性能及快淬薄带热稳定性的影响。与Nd2Fe14B相比，硬磁相Dy2Fe14B具有较高的磁晶各向异性场HA和较低的饱和磁极化强度Js，因此，Dy元素添加能显著提高合金的内禀矫顽力Hcj，但会降低合金的剩磁Br。Dy 元素替代Nd/Pr元素，增强了快淬薄带的热稳定性，提高了晶化退火温度。较高的晶化退火温度，使快淬薄带中已经形成的微晶更容易长大，形成一些粗大晶粒，降低了粘结磁体的磁性能。1.0% 是较佳的Dy元素添加量，(Nd,Pr)9.5Dy1Fe83.5B6合金快淬粘结磁体的最大磁能积(BH)max为71.6 kJ/m3，剩磁Br为0.638 T，内禀矫顽力Hcj为611 kA/m

Effects of Dy on Magnetic Properties and Microstructure of Nanocomposite (Nd,Pr)10.5-xDyxFe83.5B6 Alloys

A series of bonded magnets of (Nd,Pr)10.5-xDyxFe83.5B6 (x=0.0, 0.5, 1.0, 1.5, 2.0, 2.5) alloys were prepared by a melt-spun method. The effects of Dy substitution on the thermal stability of as-spun ribbons, the magnetic properties and microstructures of alloys were investigated. Dy addition will enhance the intrinsic coercivity Hcj greatly, but reduce the remanence Br, because Dy2Fe14B has a higher magnetocrystalline anisotropy field HA and a lower saturation magnetic polarization Js compared to those of Nd2Fe14B. The Dy substitution for Nd/Pr enhances the thermal stability and increases the crystallization annealing temperature. The higher annealing temperature leads the fine crystallites existing in as-spun ribbons to easily growing, resulting in appearance of some bigger grains and deterioration of the bonded magnet property. The bonded magnet of (Nd,Pr)9.5Dy1Fe83.5B6 alloy with 1.0at% Dy has optimal magnetic properties, i.e (BH)max=71.6 kJ/m3, Br=0.638 T, and Hcj= 611 kA/m