中文摘要：

采用X射线衍射（XRD）、差热分析（DTA）和电子显微镜研究Ni 60 Nb 40和Ni 40 Nb 60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Ni 60 Nb 40和Ni 40 Nb 60快淬非晶相关低温纳米晶化行为的内在机制。

英文摘要：

The low-temperature crystallization behavior of Ni60Nb40and Nb60Ni40melt-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 Ni60Nb40and Ni40Nb60metallic 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 theβ-relaxation process in fragile metallic glasses.