高能球磨制备中子吸收体Fe-Dy_2O_3纳米晶粉末的研究

Preparation of Fe-Dy_2O_3 nanocrystalline powders as neutron absorber by high energy ball milling

通过高能球磨技术制备了Fe-25.68%Dy_2O_3(质量分数)纳米晶混合粉末。采用X射线衍射、扫描电镜和透射电镜对不同球磨时间的混合粉末的组织结构、晶粒大小、微观形貌以及颗粒中化学成分分布情况进行了观察和研究。实验结果表明:混合粉末经过球磨后形成了纳米晶,其组织非常均匀。球磨对Dy_2O_3组元的作用效果明显大于对Fe组元的作用效果。Fe相的衍射峰随球磨时间的增加逐渐宽化,而Dy_2O_3相衍射峰强度逐渐降低,在球磨48 h后几乎消失。结果表明随球磨时间的增加,晶粒尺寸逐渐减小,球磨初期减小很快,球磨后期减小缓慢,最后趋于一个稳定值,48 h后晶粒的平均尺寸约为20 nm。本文同时研究了纳米晶混合体形成和Dy_2O_3相固溶的原因以及微观组织演变的机制。

The nanocrystalline powders of Fe-25. 68% Dy_2O_3 were prepared by high energy ball milling for 48 h at 380 r/min rotation.Microstructure,grain size,composition and morphology of the milled Fe-25. 68% Dy_2O_3 powders were investigated by using X-ray diffraction,transmission electron microscopy and scanning electron microscopy. The results show that the nanocrystalline powders are synthesized and the homogenous nanophases are achieved. The effect of the ball milling is more evident to Dy_2O_3 phase than to Fe particle. With increasing ball milling time,the diffraction peaks of the Fe phase broadened gradually. Meanwhile,the diffraction peaks of the Dy_2O_3 phase weakened gradually and disappeared almost after milling for 48 h. At the initial stage,crystalline size of the Fe phase is reduced significantly,then reduces slowly and tends to a stable value in the later stage of the ball milling. After milling for 48 h,the average crystalline size is about 20 nm. The mechanisms of solid solution and nanocrystalline formation,and microstructure evolution for the milled Fe-Dy_2O_3 powders are also discussed.