关键词: 原子团簇, 自由表面, 熔化过程, 非均质形核

Abstract: The melting process of Ni atom clusters with different size has been studied by molecular dynamics simulation. The initial configuration of clusters is the structure of FCC. The results indicate that melting first occurs at the edges of the clusters, and after the outer shells started to form the liquid layer, melting of the whole clusters began from the liquid to core region. The change in the melting temperature of the clusters is size dependent. The melting process can be referred as heterogeneous melting since the free surfaces act as the heterogeneous nucleation site for the liquid phase; for comparison, the melting point of the bulk solid of Ni has been simulated. It can be superheated up to 400 K above the experimental melting point. For system without free surface, there is no effective heterogeneous nucleation site for the liquid phase,melting is an intrinsic process initiated by a spontaneous homogeneous nucleation mechanism.

Key words: Atom cluster, Free surface, Melting process, Heterogeneous nucleation