Size Effect of Thermal Stability of Zr47Ti12.9Cu11Ni9.6 -Be16.7Nb2.8 Metallic Glass

摘要:

采用真空铜模吸铸和单辊真空薄带技术制备出直径5 mm的Zr47Ti12.9Cu11Ni9.6Be16.7Nb2.8金属玻璃棒材和相同成分厚30 μm的金属玻璃薄带。利用热分析技术和Kissinger方法分析计算了不同尺寸金属玻璃的热稳定性参数，主要包括：玻璃转变温度Tg，晶化温度Tx，玻璃转变和晶化激活能Eg、Ex等。结果表明：Zr47Ti12.9Cu11Ni9.6Be16.7Nb2.8金属玻璃在热稳定性上表现出“越小越稳定”的特征，薄带的热稳定性参数均高于棒材，表现出更好的热稳定性。不同尺寸Zr47Ti12.9Cu11Ni9.6Be16.7Nb2.8金属玻璃的晶化行为进一步验证了这一特征：在晶化温度远低于金属玻璃薄带情况下，棒材却更易晶化，晶化过程中获得了比金属玻璃薄带更加完整的晶化组织

Abstract:

The bulk glassy cylinders with a diameter of 5 mm and the ribbons of 30 μm in thickness of Zr47Ti12.9Cu11Ni9.6Be16.7Nb2.8 metallic glass were prepared by suction casting and melt spinning，respectively. The thermal stability parameters such as glass transition temperature Tg, onset crystallization temperature Tx, glass transition and crystallization activation energies Eg, Ex, etc., were measured by Differential Scanning Calorimetry and the Kissinger equation. The results reveal that the thinner ribbon sample has higher thermal stability and the metallic glass exhibits a “the smaller, the more stable” characteristic. The crystallization behaviors of different size samples also verify the above mentioned characteristic further: in the case of the crystallization of the bulk cylinder being lower than that of the glassy ribbon, the cylinder is crystallized more easily, and its crystallization microstructure is more integral than that of the glassy ribbon.