摘要
采用高分辨率电镀观测铸态Zr60Al15Ni25的微观结构。X-射线分析表明,铸态Zr60Al15Ni25合金为非晶态,而通过高分辨电镜发现非晶合金中存在大量的短程有序区。实验发现,非晶合金的无序程度与相对应的母合金铸锭的凝固组织密切相关。通过差示扫描量热法研究非晶合金在线性加热和等温条件下的晶化动力学。结果表明:非晶合金的晶化是预先存在的短程有序区作为晶核长大开始的三维扩散控制的过程。Zr60Al15Ni25块体非晶合金的无序程度对其晶化动力学具有明显的影响,即无序程度越大,非晶合金的晶化越迟缓。
The microstructure of as-cast Zr60Al15Ni25 bulk metallic glass was investigated by high-resolution transmission electron microscopy. It is found that there exist numerous short-range order regions （SRORs） in the metallic glass though it is identified to be amorphous by X-ray diffraction method. Furthermore, the amorphous degree shows a close correlation with the microstructure of corresponding mother ingot. The crystallization kinetics was investigated by differential scanning calorimetry under isochronal and isothermal conditions. The results show that the crystallization is triggered by the growth of the pre-existing SRORs and the growth is three-dimension diffusion-controlled. The amorphous degree of Zr60Al15Ni25 bulk metallic glass considerably influences its crystallization kinetics, namely, the more homogeneous distribution of atoms results in a more sluggish nucleation behavior.
基金
Project (50804032) supported by the National Natural Science Foundation of China
Project (2008011046) supported by the Natural Science Foundation of Shanxi Province, China
Project (20080321036) supported by the Key Technologies R & D Program of Shanxi Province, China
