Formation and description of nano-clusters formed during rapid solidification processes in liquid metals

In order to understand the formation mechanism of nano-clusters during rapid solidification process in liquid metals, a molecular dynamics (MD) simulation study for a large-scale system consisting of 400 000 atoms of liquid metal Al has been performed. To describe the clusters, especially the nano-clusters formed in the system during rapid solidification processes, a cluster-type index method (CTIM) has been proposed. It is demonstrated that the nano-clusters (such as containing 150 atoms) are formed by combining some middle clusters and they sharply differ from those obtained by gaseous deposition, ionic spray methods and so on. Though the nano-clusters have different shapes, they all have the corners that can be starting points of dendrite growth in solidification processes in liquid metals.