中文摘要：

利用扫描速率法研究纳米晶复合永磁合金Nd_（8.5）Fe_（76）Co_5Zr_3B_（6.5）Dy_1,Nd_（9.5）Fe_（75）Co_5Zr_3B_（6.5）Nb_1和Nd_（9.5）Fe_（75.4）Co_5Zr_3B_（6.5）Ga_（0.6）的磁黏滞行为,计算了合金的扰动场及磁交换长度,分析了其交互作用、微观结构和磁性能之间的关系.结果表明,3种合金的扰动场分别为4.80,4.87和5.09 k A/m;磁交换长度差别不大,分别为4.53,4.41和4.20 nm.Nd_（9.5）Fe_（75）Co_5Zr_3B_（6.5）Nb_1合金的交互作用最强,主要是因为合金中的晶粒尺寸细小（约为15 nm）且分布均匀.3种合金均呈单一的硬磁特征,其中Nd_（9.5）Fe_（75.4）Co_5Zr_3B_（6.5）Ga_（0.6）合金磁化反转的一致性最好,使得其剩磁较高,最大磁能积较大.

英文摘要：

A well known feature of ferromagnetic materials is the time dependent behavior of the magnetic polarization, i.e. magnetic viscosity, which arises from thermal activation over energy barriers. It is found that magnetic parameters, such as the fluctuation field（Hf） and the exchange interaction length（lex）, have a close relationship with the microstructure of the materials. Therefore, investigation on magnetic viscosity is helpful to understand the coercivity mechanism of ferromagnetic materials. In this work, ingots with nominal composition Nd_（8.5）Fe_（76）Co）5Zr）3B_（6.5）Dy_1, Nd_（9.5）Fe_（75）Co_5Zr_3B_（6.5）Nb_1 and Nd_（9.5）Fe_（75.4）Co）5Zr_3B_（6.5）Ga_（0.6）were prepared by arc-melting pure metals Nd, Fe, Co, Zr, Dy, Nb, Ga and Fe-B alloy in an argon atmosphere. A small portion of an ingot weighing about 5 g was re-melted in a quartz nozzle and ejected onto a rotating copper wheel in a range of 10～30 m/s. The annealing treatment was carried out at 690～710 ℃ for 4～5 min. Vibrating sample magnetometer（VSM）, XRD and TEM were used to study magnetic viscosity behavior and exchange interaction for Nd2Fe14B/a-Fe nanocomposite permanent alloys. Furthermore, the relationship among exchange interaction, microstructure and magnetic property was discussed. For the nanocomposite Nd_（8.5）Fe_（76）Co_5Zr_3B_（6.5）Dy_1, Nd_（9.5）Fe_（75）Co_5Zr_3B_（6.5）Nb_1 and Nd_（9.5）Fe_（75.4）Co_5Zr_3B_（6.5）Ga_（0.6）alloys,Hfand lexwere obtaind by sweep rate measurement. The Hfwere 4.80, 4.87 and 5.09 k A/m, and lexwere 4.53, 4.41 and 4.20 nm for permanent Nd_（8.5）Fe_（76）Co_5Zr_3B_（6.5）Dy_1, Nd_（9.5）Fe_（75）Co_5Zr_3B_（6.5）Nb_1 and Nd_（9.5）Fe_（75.4）Co_5Zr_3B_（6.5）Ga_（0.6）alloys, respectively. It suggested that the lexhad a minor change. The Nd_（9.5）Fe_（75）Co_5Zr_3B_（6.5）Nb_1 alloy had the strongest exchange interaction among three alloys in this work. It is due to a refined microstructure and uniform d