(1. 大连理工大学 材料科学与工程学院，大连 116024；
2. 中国科学院 金属研究所 沈阳材料科学国家实验室，沈阳 110016；
3. 大连理工大学 物理与光电工程学院，大连 116024)
摘 要: 采用X射线衍射(XRD)、差热分析(DTA)和电子显微镜研究Ni60Nb40和Ni40Nb60快淬非晶的晶化行为。结果表明，在10 K/min加热速率下采用差热分析测得Ni60Nb40和Ni40Nb60的非晶初始晶化温度分别为913和917 K，且两种非晶样品在低于各自初始晶化温度退火时均发生了晶化。其中，Ni60Nb40样品经763 K退火48 h后仍保持非晶态，而经873 K退火1 h后，则析出面心立方纳米晶颗粒；对于Ni40Nb60非晶合金，在763 K温度下退火48 h就发生晶化，析出面心立方纳米相。晶化样品中均发生明显的成分偏聚现象。结合金属玻璃中的微结构与动力学不均匀性以及β弛豫过程，初步探讨Ni60Nb40和Ni40Nb60快淬非晶相关低温纳米晶化行为的内在机制。
关键字: Ni60Nb40；Ni40Nb60；非晶；纳米晶；热稳定性
（1. School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China;
2. Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences,
Shenyang 110016, China;
3. School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024, China）
Abstract:The low-temperature crystallization behavior of Ni60Nb40 and Nb60Ni40 melt-spun metallic glasses was studied by X-ray diffractometry (XRD), differential thermal analysis (DTA) and electron microscopy. The results show that the initial crystallization temperatures of Ni60Nb40 and Ni40Nb60 metallic glasses are 913 K and 917 K, respectively, at a constant heating rate of 10 K/min. After annealing at temperatures below initial crystallization temperature, these two metallic glasses crystallize. Ni60Nb40 metallic glass preserves the amorphous state after annealing at 763 K for 48 h, while nanocrystals with face-centered cubic structure forms in the amorphous matrix after annealing at 873 K for 1 h. Nanocrystallization of Nb60Ni40 metallic glass occurs when the sample is annealed at 763 K for 48 h. Scanning transmission electron microscopy analysis gives convincing evidence of composition separation in these nanocrystallized microstructures, and the underlying mechanism was discussed in light of the existence of microstructural and dynamic heterogeneity and the β-relaxation process in fragile metallic glasses.
Key words: Ni60Nb40; Ni40Nb60 metallic glasses; nanocrystallization; thermal stability
