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采用分子动力学方法和Quantum Sutton-Chen(Q-SC)多体势对由5万个液态金属铜(Cu)原子构成的系统在三个不同冷却速率下的凝固过程中微观团簇结构转变的影响进行了模拟研究.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,对凝固过程中微观团簇结构的演变特性进行了分析研究.结果发现:由非晶体向晶体转变的临界速度约为1.0×1013 K/s,在此冷速下系统形成非晶体和晶体以一定比例并存的混合结构;在冷速为1.0×1014 K/s冷却时系统形成以1551、1541、1532、1431键型为主的非晶体结构,非晶转化温度约为673K;在以4.0×1012 K/s速度冷却时,系统从673K就开始结晶,并形成以1421和1422二种键型或由这二种键型构成的面心立方(FCC)(12 0 0 0 12 0)和六角立方(HCP)(12 0 0 0 6 6)基本原子团为主的晶体结构,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微观团簇结构形成过程中占主导地位.同时发现,冷速对金属Cu系统中的FCC结构和HCP结构的相对比例有显著的影响,冷速越低,FCC基本原子团以及由其构成的团簇结构越多.
The microstructure evolution of the system composed of 50,000 liquid metal copper (Cu) atoms during the solidification process at three different cooling rates was investigated by molecular dynamics and Quantum Sutton-Chen (Q-SC) (CBSM-2) and visualization analysis were used to analyze the evolution of the microstructure of the microstructure during the solidification process The results show that the critical speed of the transition from amorphous to crystalline is about 1.0 × 1013 K / s, and the mixed structure of amorphous and crystal coexist at a certain ratio under the cold condition. When the cooling rate is 1.0 × When cooling at 1014 K / s, the system formed 1551, 1541, 1532 and 1431 bond-type amorphous structure with an amorphous transition temperature of 673K. When cooling at 4.0 × 1012 K / s, the system started from 673K Crystallized and formed into a face centered cubic (FCC) (12 0 0 0 12 0) and a hexagonal cubic (HCP) (12 0 0 0 6 6) basic type composed of two kinds of bonds of 1421 and 1422 or both Atomic-based crystal structure, especially by the 1421 bond-type face-centered cubic (12 0 0 0 12 0 ) Basic radicals dominated the crystal growth and microstructure formation.It was also found that the cooling rate had a significant effect on the relative proportions of FCC and HCP structures in the metallic Cu system.The lower the cooling rate, As well as the structure of the cluster formed by it.