The effect of particle size and dist ribution of rapidly quenching NdFeB magnetic powder on the magnet-ic properties of polymer-bonded NdFeB permanent magnet was studied. The results show that the particle size and the dist ribution of rapidly quenching NdFeB magnetic powder have significant effects on the magnetic properties of polymer-bonded NdFeB permanent magnet. As long as the size and the dist ribution of rapidly quenching NdFeB powder are within the right range, high magnetic properties of polymer-bonded NdFeB permanent magnet can be ob-tained. This is mainly because the rapidly quenching NdFeB magnetic powder has high hardness and is scale-shaped. The larger the size of rapidly quenching NdFeB particles is, the more difficult it is to obtain high density of bonded NdFeB magnet. However the structure will be dest royed if the size is too small. It results in the deterioration of magnetic properties. The mechanism is also discussed.

通过X射线衍射（XRD）、扫描电镜（SEM）和能谱分析（EDX）等手段重点研究了Sm-Fe17合金在氢化2歧化过程中的相组成、相的变化以及微观结构的演化规律。研究表明：在0.1MPa的H2气氛下，Sm-Fe17合金首先吸氢；400℃时合金出现部分脱氢现象；在T≥500℃逐渐开始歧化为SmHx和α2Fe，同时生成了大量的微晶或非晶组织；随着温度的升高，合金中的微晶非晶逐渐晶化，750℃时晶化完全，晶粒长大至20～100nm。通过对Sm-Fe17合金的氢化2歧化过程研究，建立了该过程的微观结构变化规律的物理模型。

The optimum quenching rates and annealing conditions to prepare near stoichiometrical (Nd,Pr)12 (FeCoZr) 82B6 bonded magnets were investigated by using sub-overquenching and post annealing method. The quenching rates, annealing temperatures, and annealing time directly influence the microstructure and magnetic properties of alloy ribbons. The opti-mum magnetic properties of bonded magnets are achieved by melt spinning at 24ms-1wheel surface speed, annealing at 655℃ for 10 min, and bonding with 3.25% (mass fraction) epoxy. The best magnetic properties of remanence Br, in-trinsic coercivity Hci and maximum energy product (BH) max are 0. 669 T, 811 kA•m-1, and 75kJ •m-3, respectively.

By using sub-overquenching and annealing method which has a wide processing window, (Nd, Pr) x (Fe-CoZr) 94-xB6 (x = 12, 10. 5, 10, 9) bonded magnets were prepared and the effect of rare earths content on magnetic prop-erties was investigated. Being spun at sub-overquenching speed the as-spun ribbons consist of amorphous phases mixed with fine crystallites. After crystallization under optimum annealing conditions and bonded with 3.25% (mass fraction) e-poxy, the magnets obtained the optimum magnetic properties. The rare earths content directly determines the magnetic properties. With the reduction of rare earths content, Br increases but Hci and (BH) max decrease. x=10 is the critical value for the magnetic properties change. Below this value, Br increases slowly meanwhile Hci and (BH) max decrease strongly because alloy contains extra fractions of soft magnetic phase which are not coupled with the hard magnetic phase. This experimental result is consistent with the calculated results using the model of volume fraction of soft magnetic phase coupled completely suggested.

The influence of Pr on thermal stability, microstructure, and magnetic properties of melt2spun (Nd1-x Prx) 10.5 (FeCoZr) 83.5B6 (x=0,0.2,0.4,0.6,0.8,1.0) alloy was investigated. By sub2overquenching to get the mixture of amorphous and fine crystallites and post annealing under the optimum conditions,bonded magnets with the best magnetic properties were prepared. With the increase of Pr content, Hci increases, but Br decreases. (BH) max of magnets bonded with 3.25 %(mass fraction) epoxy reaches the maximum of 7016 kJ•m-3 at x=0.6～0.8. Substitution of Pr for Nd causes the crystallization temperature and crystallization energy to decrease. This ther-mal stability difference results in that (Nd0.2Pr0.8) 10.5 (FeCoZr) 83.5B6 alloy has a rougher and more inhomogeneous microstructure than that of (Nd0.8Pr0.2) 10.5 (FeCoZr) 83.5B6 alloy, furthermore, leads to the decrease of B r with the increase of Pr content.