Atomic structure and dynamics properties of Cu_(50)Zr_(50) films

摘要

In this paper, the structural and dynamic properties of Cu_(50)Zr_(50) films are investigated by molecular dynamics simulations. Our results show that the dynamics of the surface atoms are much faster than those of the bulk. Especially, the diffusion coefficient of the surface atoms is about forty times larger than that of the bulk at 600 K, which qualitatively agrees with the experimental results. Meanwhile, we find that the population of the icosahedral (-like) clusters in the surface region is obviously higher than that of the bulk, which prevents the surface from crystallization. A new method to determine the string-like collective atomic motion is introduced in the paper, and it suggests a possible connection between the glass formation ability and collective atomic motion. By using the method, the effects of surface on collective motion are illustrated. Our results show that the string-like collective atomic motion of surface atoms is weakened while that of the interior atoms is strengthened. The studies clearly explain the effects of surface on the structural and dynamic properties of Cu_(50)Zr_(50) films from the atomic scale.