基于快速热分析技术Al基体中纳米Bi液滴凝固特性  

Solidification Behavior of Nano-sized Bismuth Droplets Embedded in Aluminum Matrix Based on Fast Scanning Calorimetry

作　　者：张全良[1,2] 赵炳戈[1,2] 张令[1,2] 吴漫楠 高玉来[1,2] 

机构地区：[1]上海大学省部共建高品质特殊钢冶金与制备国家重点实验室,上海200072 [2]上海大学微结构重点实验室,上海200436

出　　处：《上海金属》2017年第6期50-54,共5页Shanghai Metals

基　　金：上海高校特聘教授(东方学者)计划(No.TP2014042);国家自然科学基金(No.51671123)

摘　　要：通过甩带法制备了镶嵌在Al基体中的纳米Bi液滴,并借助X射线衍射(XRD)、扫描电子显微镜(SEM)及能谱分析仪(EDS)对样品的组织、形貌和成分进行了系统的表征。结果表明,样品中Bi有两种存在形式:一种是镶嵌在Al晶粒内部的大量纳米Bi颗粒,另一种是分布于晶界处的微米级Bi颗粒。基于经典形核理论,利用快速热分析仪详细研究了镶嵌于Al基体Bi液滴的凝固特性,发现纳米Bi液滴存在两个凝固峰。理论计算两个凝固峰形核接触角分别为90°和93°,说明纳米Bi液滴在Al基体不同晶面催化作用下形核,并造成了纳米Bi液滴凝固双放热峰的产生。此外,过冷度良好的重复性突出了快速热分析技术结合镶嵌纳米液滴研究金属异质形核的独特优势。Al-10 Bi(mass fraction,%) ribbons with nano-sized bismuth droplets embedded in aluminum matrix were prepared by melt spinning technique. The microstructure,morphology and composition of ribbons were systematically characterized by X-ray diffraction(XRD),scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy(EDS). The results showed that there were two forms of Bi in the sample,one was a large amount of nano-sized droplets embedded in aluminum matrix,the other was the micron-sized bismuth droplets distributed at the grain boundaries of samples. The solidification behavior of nano-sized bismuth droplets was studied by using fast scanning calorimetry(FSC). Two exothermic peaks originating from the solidification of nano-sized bismuth droplets were detected with contact angle about 90° and 93°,respectively. Based on the classical nucleation theory,it was concluded that the overlapped two exothermic peaks revealed the nucleation of nano-sized bismuth droplets which is catalyzed by different crystal planes of Al matrix. Besides, the repeatability of the undercooling data reflected the unique advantages of combining the embedded droplet technique and FSC to study the heterogeneous nucleation behavior.

关 键 词：异质形核 过冷度 镶嵌纳米液滴 快速热分析 

分 类 号：O657.31[理学—分析化学]