Formation Properties and Characterization of Nano-Clusters during Solidification Processes of Liquid Metals Al

A simulation study has been performed for a large liquid metal system consisting of 1,000,000 Al atoms to investigate the formation and evolution of nano-clusters during the solidification processes, adopting the Honeycutt-Andersen (HA) bond-type index method and the cluster-type index method (CTIM-2) to analyze and characterize various types of basic clusters. The result indicates that during the solidification processes of liquid metal Al, the basic icosahedron clusters of (12 0 12 00 0), related to 1551 bond-type plays the most important role in the microstructure transition; The nano-clusters are mainly formed by the mutual combination of basic icosahedron clusters and other basic clusters of (13 1 10 2 0 0), (14 2 8 4 0 0) and so on. Within the nano-clusters, the center atoms of various basic clusters are all bonded each other with single-bond or multi-bonds, and the more the number of the center atoms bonded with multi-bonds, the more stable the nano-cluster would be. In this system, there are always a few basic cluster of hcp (12 00 0 6 6) and tDh (12 02 00 10) related to the crystal structures.