u80Si20液态合金微观结构和动力学性质的实验和理论研究

In this study, the local structures of liquid Cu80Si20 alloy have been studied by X-ray diffraction as well as ab initio molecular dynamics simulations. The dynamical properties are calculated. The pair-correlation functions and the structure factors derived from the three dimensional coordinates of the MD configurations agree well with the experimental results. The local structure of the liquids is analyzed using Honeycutt-Andersen indices, Voronoi tessellation, and an atomic cluster alignment method. The Honeycutt-Andersen indices analysis shows that the pentagonal bipyramid, a fragment of an icosahedron, plays a dominant role in the short-range order of the Cu80Si20 liquid. The HA indices corresponding to the pentagonal bipyramid increases dramatically with decreasing temperature. Voronoi tessellation analysis indicates while the liquid does exhibit a strong icosahedral SRO, FCC-like SRO is also measureable. The results from Voronoi tessellation analysis are further confirmed using the atomic cluster alignment method. In particular, the cluster alignment reveals the development of Cu-centered FCC clusters as the liquid approaches its melting temperature. Finally, self-diffusion constants as the function of temperature for both Cu and Si species are calculated.