TbCu7型SmFe9合金氮化过程中氮原子的扩散

Diffusion of Nitrogen Atoms During Preparation of Nitride TbCu_7-type SmFe_9 Alloy

研究了在制备TbCu7型SmFe9Nx各向同性粘结磁粉过程中氮原子的扩散行为,分析并讨论了氮化温度、氮化时间、颗粒尺寸与样品氮含量的关系,以及氮原子在SmFe9合金粉末颗粒内部的分布情况。氮化前后XRD表明,氮化过程中氮原子经扩散进入SmFe9合金1∶7相晶格间隙,生成了TbCu7型SmFe9Nx间隙化合物;通过氮化后样品热磁曲线分析及Fick扩散第二定律理论计算,表明氮化后颗粒内部氮含量非均匀分布,越靠近颗粒中心,氮含量越低;计算得出了氮原子在SmFe9合金中的扩散频率因子(D0=9.565×10-4m2.s-1)和扩散激活能(Q=147.3 kJ.mol-1)。

The diffusion behavior of the nitrogen atoms during the preparation of TbCu7-type SmFe9Nx isotrop- ie bonded magnetic powder was investigated. The rela- tion between the diffusion temperatures, diffusion time, particle size with nitrogen content in samples was measured, and the distribution of nitrogen atoms in the SmFe9 alloy particles was analyzed. The XRD of the SmFe9 particles nitrided and without nitridation showed that the nitrogen atoms diffused into lattice space of the 1 ： 7 phases of SmFe9 alloy during nitrida- tion process, and the interstitial compounds genera-ted. Through analyzing magnetization curves of the samples after nitridation and calculation by Fick sec- ond diffusion law, the nitrogen content in SmFe9 inter- nal was non-uniform distribution after nitridation, and the nearer the center of the particle, the lower nitrogen content. The values of the diffusion frequency factor （DO =9.565 ×10 4 m2·s-1） and the diffusion activa- tion energy （ Q = 147. 282 kJ·mol-1 ） for the nitrogen atoms diffusion in SmFe9 particle were obtained through computation.