摘要
This work investigated the response of Cu46Zr42Al7Y5 glass ribbons to both dynamic and static heating using differential scanning calorimeter （DSC）. The DSC curve manifests three exothermic responses to dynamic heating, among which the first and the third one are the signatures of the normal sub-Tg （Tg, glass transition temperature） relaxation and the crystallization process, respectively. The second one is attributed to a partial overlap between the endothermic response to the glass transition and the exothermic response to the formation of ordered clusters. The cluster ordering, which begins at the final stage of glass transition, has been verified by the differences in the activation energy of the sub-Tg relax- ation, the cluster ordering and primary crystallization for both the as-spun and annealed ribbons. The cluster ordering could be driven by the large difference between the Zr-Y mixing enthalpy and the Al-Y （or Cu-Y） mixing enthalpy. The findings contribute to distinguishing between phase separation and clusters motion scenarios.
利用快冷-退火-量热法探索了Cu_(46)Zr_(42)Al_7Y_5金属玻璃条带在升温和等温退火过程中的热力学变化.实验结果表明,Cu_(46)Zr_(42)Al_7Y_5金属玻璃条带的升温热流曲线上存在3个放热峰.分析发现,第1个放热峰表征了金属玻璃条带的Sub-Tg弛豫行为;第2个放热峰是加热过程中团簇有序化放热现象与玻璃转变吸热现象叠加的结果;第3个放热峰对应金属玻璃的晶化过程.通过计算玻璃转变、团簇有序化及晶化过程的激活能,研究非等温退火后各激活能的变化,从能量角度证明了加热过程中发生团簇有序化现象的合理性.基于元素混合焓分析发现,锆-钇原子之间与铝-钇(或铜-钇)原子之间混合焓的巨大差异极有可能是团簇有序化现象发生的诱导因素.本文为揭示相分离和团簇运动机理提供了新思路和新途径.
基金
supported by the National Natural Science Foundation of China(51171090
51571131)
the Fundamental Research Funds of Shandong University(2014YQ008)
