(嘉应学院物理与光信息科技学院，梅州 514015)
摘 要: 采用分子动力学方法和Quantum Sutton-Chen多体势，对2万个液态金属铜(Cu)原子在两个不同冷速凝固过程中其微观团簇结构的形成特性以及晶体的成核生长进行模拟。运用双体分布函数、Honeycutt-Andersen(HA)键型指数法、原子团类型指数法(CTIM-2)和可视化分析等方法，对凝固过程中微观结构转变和原子团簇的微观结构演变特性进行分析。结果表明：冷却速率为4.0×1012 K/s和2.0×1012K/s时，系统形成以1421、1422键型或由这两种键型构成的面心立方(FCC)(12 0 0 0 12 0)和六角密集(HCP)基本原子团(12 0 0 0 6 6)为主体的晶体结构；尤其是由1421键型构成的面心立方(12 0 0 0 12 0)基本原子团在晶体生长和对微观结构演变的影响占主导地位。两种冷却速度下的结晶温度分别为673K和773K，即冷却速度越慢，结晶温度越高；系统最终形成了由FCC和HCP组成的混合晶体结构，但以FCC晶体结构为主；FCC(12 0 0 0 12 0)基本原子团在慢速低温时具有较好的遗传特性，基本原子团之间很容易连接在一起构成较大的纳米级大团簇结构。
关键字: 液态金属Cu；分子动力学模拟；Q-SC多体势；微观结构演变；成核；生长
（School of Physics and Optical Information Sciences, Jiaying University, Meizhou 514015, China）
Abstract:A simulation study was performed on the formation properties of micro-cluster structures and nucleation and growth of crystals during solidification process of 20000 liquid metal Cu atoms at two different cooling rates by adopting the molecular dynamics method and Quantum Sutton-Chen multi-body potential.The pair distribution function,the bond-type index method of Honeycutt-Andersen(HA),cluster-type index method(CTIM-2)and visualization analysis were used to analyze and study the transition of microstructures and evolution properties of micro-cluster configurations during solidification process. The results show that the crystal structures form mainly with the 1421 and 1422 bond-types or the FCC(12 0 0 0 12 0) basic cluster, and the HCP(12 0 0 0 6 6)basic cluster being composed of the two bond-types at the cooling rates of 4.0×1012K/s and 2.0×1012K/s.Especially, the FCC(12 0 0 0 12 0) basic clusters consisting of 1421 bond-type occupy a dominant position in crystal-growth and the effect of microstructures evolution. Meanwhile,it has been found that the temperatures of crystallization are 673K and 773K under two cooling rates,respectively. Namely,the lower the cooling speed is, the higher the crystal temperature is, and finally the system forms the crystal and amorphous mixed coexistence structures of FCC ad HCP,but the FCC crystal structures is major. When the cooling rates and temperature are lower, the FCC(12 0 0 0 12 0)basic cluster posseses better genetic characteristic, and the basic clusters are easier to form bigger nano-cluster structure by bonding together.
Key words: liquid metal Cu; molecular dynamics simulation; Q-SC multi-body potential; microstructure evolution; nucleation; growth
