引用本文
  •    [点击复制]
  •    [点击复制]
【打印本页】 【在线阅读全文】【下载PDF全文】 查看/发表评论下载PDF阅读器关闭

←前一篇|后一篇→

过刊浏览    高级检索

本文已被:浏览 66次   下载 100 本文二维码信息
码上扫一扫!
不同冷速下SiGe纳米液滴快速凝固过程中的微观结构演变
肖婷,田泽安,高廷红,郭笑天,莫云飞,稂林,周尧,梁永超
0
(贵州大学大数据与信息工程学院,贵州省公共大数据重点实验室,贵阳 550025;安顺学院数理学院,安顺 561000;长沙学院,长沙 410000;湖南大学材料科学与工程学院,长沙 410000)
摘要:
采用分子动力学方法模拟了7种不同冷速下Si50Ge50纳米液滴快速凝固过程,利用双体分布函数、原子平均能量、最大标准团簇分析法、键角分布函数、二面角分布及可视化方法等对体系微观结构的演变进行了分析。研究结果表明: 当冷速R≥1×1010 K/s时,系统形成非晶态结构; R≤5×109 K/s时,系统形成以闪锌矿和纤锌矿结构相互嵌套的近似球形的纳米晶体,且纳米液滴起始结晶温度随冷速降低而降低。
关键词:  SiGe纳米液滴,冷速,微观结构,分子动力学模拟,凝固过程
DOI:10.13380/j.ltpl.2019.01.008
基金项目:
Microstructural Evolution of SiGe Nano-droplet During Rapid Solidification Process at Different Cooling Rates
XIAO Ting,TIAN Zean,GAO Tinghong,GUO Xiaotian,MO Yunfei,LANG Lin,ZHOU Yao,LIANG Yongchao
(College of Big Data and Information Engineering, Guizhou University, Guizhou Provincial Key Laboratory of Big Data, Guiyang 550025, China;Anshun College of Mathematics and Physics, Anshun, 561000;Changsha College, Changsha, 410000;College of Materials Science and Engineering, Hunan University, Changsha, 410000)
Abstract:
A group of MD simulations were conducted at 7 cooling rates to study the evolution of microstructure during rapid solidification of SiGe nano-droplets containing 500 Si atoms and 500 Ge atoms. And the structural evolution of nano-droplet has been investigated by the pair distribution function (PDF), the energy-temperature (E-T) relation, the largest standard cluster analysis (LSCA), the angle distribution function (ADF), dihedral angle distribution function (DADF) and the visualization methods. The PDF curves at 300 K reveal that as R≥1×1010 K/s, a 1000-atom Si50Ge50 nano-droplet can be vitrified; as R≤5×109 K/s, it crystallizes. Therefore, the critical cooling rate for vitrification of 1000-atom Si50Ge50 nano-droplets is between 1×1010 K/s and 5×109 K/s; and E-T curves further indicates that for crystallization, the lower the cooling rate, the lower the onset temperature of crystallization. Further analysis based on LSCA reveals that during crystallization processes, the kind number of LSCs decreases remarkably and the number of [4-000] cluster jump-up significantly; the bond angle distribution of the system gradually approaches 109°that is for perfect cells in sphalerite or wurtzite crystals; furthermore the peaks on dihedral angle distribution function curves locate at 0°, 60°, 120°, and 180°, dominated by 60°and 180°that are the characteristic for sphalerite crystals. As R≤5×109 K/s, the system is composed of sphalerite atoms, less wurtzite atoms, and few others in the final state (300 K); and the slower the cooling rate, the more the number of sphalerite atoms. In the final solids, atoms comprise 6-atom or 5-atom rings with less irregular big loops.
Key words:  Si50Ge50 Nano-droplet, Cooling Rate, Microstructure, Molecular dynamics simulation, solidification process.

用微信扫一扫

用微信扫一扫