冷速对液态金属Mg凝固过程中微观结构演变的影响

发布时间：2018-04-16 21:17

本文选题：液态金属Mg + 快速凝固　；参考：《物理学报》2017年01期

【摘要】：采用分子动力学方法对不同冷速下液态金属镁(Mg)快速凝固过程中的微观结构演变进行了模拟研究.并采用能量-温度(E-T)曲线、双体分布函数、Honeycutt-Andersen键型指数法、原子团簇类型指数法(CTIM-3)以及三维可视化等方法系统地考察了凝固过程中微观结构演变与相转变过程.结果发现:在以冷速为1×10~(11)K/s的凝固过程中,亚稳态bcc相优先形成,随后大量解体,其变化规律符合Ostwald规则,系统最终形成以hcp结构为主体与fcc结构共存,中间还夹杂部分bcc结构的致密晶体结构.在1×10~(12)K/s冷速下,结晶过程呈现迟缓现象,形成bcc结构的初始温度降低,系统形成以hcp居多、与bcc和fcc三相共存的结构,且因相互竞争、相互制约而导致不易形成粗大的晶粒结构.而在1×10~(13)K/s冷速下,系统则形成以1551,1541,1431键型为主的多种非晶态基本原子团组成的非晶态结构.此外,在冷速1×10~(12)与1×10~(13)K/s之间的确存在一个形成非晶态结构的临界冷速.
[Abstract]:The microstructure evolution of liquid magnesium magnesium (mg) during rapid solidification at different cooling rates was simulated by molecular dynamics method.The evolution of microstructure and phase transition during solidification were systematically investigated by means of energy-temperature E-T curve, double body distribution function Honeyson-Andersen bond index method, atomic cluster type index method CTIM-3) and three-dimensional visualization.The results show that the metastable bcc phase is formed preferentially in the solidification process with a cooling rate of 1 脳 10~(11)K/s, and then disintegrates in large numbers, and its variation law conforms to the Ostwald rule. The system finally forms a system in which the hcp structure is the main body and the fcc structure coexists.The dense crystal structure of the bcc structure is also embedded in the middle.At the cooling rate of 1 脳 10~(12)K/s, the crystallization process is slow and the initial temperature of the formation of bcc structure decreases. The system is composed of hcp, which coexists with bcc and fcc, and is not easy to form coarse grain structure due to mutual competition and mutual restriction.At a cooling rate of 1 脳 10~(13)K/s, the amorphous structure of the system is composed of a variety of amorphous basic clusters, which are mainly composed of 1551 / 1541 / 1431 bond type.In addition, there is a critical cooling rate of amorphous structure between 1 脳 10 ~ (12) and 1 脳 10~(13)K/s.
【作者单位】：湖南大学材料科学与工程学院;湖南大学物理与微电子科学学院;贵州大学大数据与信息工程学院;郑州大学材料科学与工程学院;
【基金】：国家自然科学基金(批准号:51102090) 新世纪优秀人才支持计划(批准号:NCET-12-0170) 湖南省自然科学基金(批准号:2016JJ2023)资助的课题~~
【分类号】：TG146.22

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