Simulation of formation and evolution of nano-clusters during rapid solidification of liquid Ca_(70)Mg_(30) alloy  

液态Ca_(70)Mg_(30)合金快速凝固过程中纳米团簇结构形成演变特性模拟(英文)

作　　者：周丽丽[1,2] 刘让苏[2] 田泽安[2,3] 

机构地区：[1]赣南医学院信息工程学院,赣州341000 [2]湖南大学物理与微电子科学学院,长沙410082 [3]School of Materials Science and Engineering University of New South Wales

出　　处：《Transactions of Nonferrous Metals Society of China》2013年第8期2354-2360,共7页中国有色金属学报（英文版）

基　　金：Project(50831003) supported by the National Natural Science Foundation of China;Project(20114BAB215026) supported by Jiangxi Provincial Natural Science Foundation,China;Project(ZD201002) supported by Fund for Basic Scientific Research of Gannan Medical University,China

摘　　要：A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM） was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5~1011 K/S, and glass transition temperature Tg is about 530 K; the icosahedron cluster of （12 0 12 0） plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.采用分子动力学方法对液态Ca70Mg30合金快速凝固过程中纳米团簇结构的形成和演变特性进行模拟。采用原子团类型指数法(CTIM)对凝固过程中纳米团簇结构的演变进行分析。结果表明:系统在5×1011K/s的冷速条件下形成以1551、1541和1431为主的非晶态结构,非晶转变温度约为530 K;(12 0 12 0)二十面体基本原子团对系统非晶结构的形成起到决定性的作用,并且原子半径较小的Mg原子更容易占据二十面体基本原子团中心原子的位置;同时,纳米团簇主要是通过中等尺寸团簇的合并而形成,纳米级大团簇的形成演变过程呈现出类似于非晶晶化过程的3个阶段式的变化。

关 键 词：NANO-CLUSTERS Ca70Mg30 alloy rapid solidification molecular dynamics simulation 

分 类 号：TG111[金属学及工艺—物理冶金]