基于快速热分析技术Al基体中纳米Bi液滴凝固特性

发布时间：2018-01-19 10:28

本文关键词： 异质形核过冷度镶嵌纳米液滴快速热分析　出处：《上海金属》2017年06期 　论文类型：期刊论文

【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。
[Abstract]:Nanocrystalline Bi droplets embedded in Al matrix were prepared by banding method. The microstructure of the samples was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive analyzer (EDS). The morphology and composition of Bi were systematically characterized. The results show that there are two forms of Bi in the sample: one is a large number of nanocrystalline Bi particles embedded in Al grains. Based on the classical nucleation theory, the solidification characteristics of Bi droplets embedded in Al matrix have been studied in detail by using a rapid thermal analyzer. It is found that there are two solidification peaks in nanocrystalline Bi droplets, and the contact angles of the two solidification peaks are 90 掳and 93 掳, respectively, indicating that the nanocrystalline Bi droplets are nucleated under the catalysis of different crystal planes of Al matrix. In addition, the reproducibility of supercooling highlights the unique advantages of rapid thermal analysis combined with embedded nano-droplets in the study of heterogeneous nucleation of metals.
【作者单位】：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;上海大学微结构重点实验室;
【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)
【分类号】：TG115
【正文快照】： 形核作为凝固过程第一步对组织影响显著,进而改变铸件的宏观性能。金属熔体中不可避免地存在着各种各样的杂质,故形核大多以异质形核的方式进行[1-2]。研究异质形核最大的障碍是消除金属熔体中不可预知的杂质,一种行之有效的方法是减小熔体的体积,进而提高过冷度,在此思路下,

【相似文献】