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| 1 | Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al显示文摘A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12 0 12 0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals. | LIU Rangsu, DONG Kejun, LIU Fengxiang, ZHENG Caixing, LIU Hairong & LI Jiyong Department of Applied Physics, Hunan University, Changsha 410082, China College of Materials Science and Engineering, Hunan University, Changsha 410082, China College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China | 2005 | Science China(Physics,Mechanics & Astronomy)2005，48，1： | 7 |
| 2 | Microstructural Transitions during the Rapid Cooling Process of Liquid Metal Al显示文摘From a molecular-dynamics simulation study on the rapid cooling process of liquid metal Al, it is demonstrated that the microscopic structure transitions is mainly determined by the changes of various microstructural configurations. There are tWo obvious phase transition points during the rapid cooling process. The first transition point is consistent with the well-known glass transition. The second one is a new weaker transition at low temperature. The cluster having 7-fold symmetry still exists in the supercooled liquid metal Al, though it occupies only 0.1% of the total number of clusters in the system and disappears below 550K, namely, it can not exist in the glassy state. These results will give us a new way to understand the structural transition at microscopic level. | Li, Jiyong Liu, Rangsu Xie, Quan Peng, Ping Zhou, Zheng | 1998 | Journal of Materials Science & Technology1998，14，5： | 5 |
| 3 | Simulation study for atomic size and alloying effects during forming processes of amorphous alloys显示文摘A molecular dynamics (MD) simulation study has been performed for the solidification processes of two binary liquid alloys Ag6Cu4 and CuNi by adopting the quantum Sutton-Chen many-body potentials. By analyzing bond-types, it is demonstrated that at the cooling rate of 21012K/s, the CuNi forms fcc crystal structures, while the Ag6Cu4 forms amorphous structures. The original reason is that the atomic radius ratio (1.13) of the CuAg is bigger than that (1.025) of the CuNi. This shows that the atomic size difference is indeed the main factor for forming amorphous alloys. Moreover, for Ag60Cu40, corresponding to the deep eutectic point in the phase diagram, it forms amorphous structure easily. This confirms that as to the forming tendency and stability of amorphous alloys, the alloying effect plays a key role. In addition, having analyzed the transformation of microstructures by using the bond-type index and cluster-type index methods, not only the key role of the icosahedral configuration to the formation and stability of amorphous alloys can be explained, but also the solidification processes of liquid metals and the characteristics of amorphous structures can be further understood. | ZHENG Caixing LIU Rangsu PENG Ping ZHOU Qunyi | 2004 | Science China(Physics,Mechanics & Astronomy)2004，47，4： | 3 |
| 4 | Simulation study on the formation and transition properties of cluster structures in liquid metals during rapid cooling processes显示文摘 | Caixing Zheng Rangsu Liu Kejun Dong Ping Peng Hairong Liu Zhongyu Xu Xiaoyong Lu | 2002 | Science in China Series A: Mathematics2002，，2： | 1 |
| 5 | Structure stability and configuration evolution of Al_n(n=3, 4, 6, 13, 19) clusters显示文摘Using a first-principles pseudo-potential plane wave method, the geometrical and electronic structures of Aln (n=3, 4, 6, 13, 19) clusters with different configurations have been calculated. Several parameters such as the binding energy Eb and the HOMO-LUMO energy gap ?EH-L have been adopted to characterize and analyze the structure stability of these clusters, and their configuration evolutions are also investigated by linear synchronous transit (LST) method. It is demonstrated that the stable configura- tions of Al3, Al4, Al6, Al13, Al19 clusters are triangle, rhombus, octahedron, icosahedron and double icosahedron, respectively. For Al6 and Al19 clusters there are metastable structures of parallelogram and octahedron, respectively, whereas in the Al3, Al4 and Al13 clusters, no metastable configuration is validated. There exist a large energy gap and a low energy barrier between the octahedron and the parallelogram of the Al6 cluster, so the transfor- mation from its metastable to stable structures is rather easy. By contrast, a small energy gap and a high energy barrier between the stable and metastable structures of Al19 cluster mean its configuration evolution from the octahedron to the double icosahedron occurs hardly, therefore the metastable octahedron configuration of Al19 cluster can be extensively detected in experiments and simulations. | PENG Ping LI Guifa ZHENG Caixing HAN Shaochang LIU Rangsu | 2006 | Science China(Technological Sciences)2006，49，4： | 1 |
| 6 | Molec- ular dynamics simulation for cooling rate dependence of solidification microstructures of silver 显示文摘 | TIAN Zhean LIU Rangsu HOU Zhaoyang | 2008 | Journal of non- crystalline solids2008，354，31： | 1 |
| 7 | A simulation study of rapid solidification and crystal configuration of Cu_(70)Ni_(30) alloy显示文摘A molecular dynamics (MD) simulation study has been performed for the rapid solidification of Cu70Ni30 adopting the quantum Sutton-Chen many-body potentials. By analyzing the bond-types and the relation of atomic average energy versus temperature, it was demonstrated that as cooling rate being 2 × 1012 K/s, the Cu70Ni30 formed fcc crystal structures and freezing point was found. In addition, having analyzed the transformation of microstructures and the detail of crystal growth by using atomic trace and visual method, not only could the formation of binary disordered solid solution be showed, but also the solidification of liquid metals and the crystal growth processes could be further understood. | ZHENG Caixing LIU Rangsu ZHOU Qunyi TIAN Ze'an WANG Xin LI Qiang | 2005 | Science China(Physics,Mechanics & Astronomy)2005，48，6： | 0 |
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