Molecular Dynamics Study Of Deposition And Tensile Deformation For Cu/Ag Bilayer Films

Limited by the spatial and temporal scales, transient behaviors of atoms cannot be observed in the experiment of the growth and micro-deformation of films. To make up for this deficiency, focuses on tracking the process of the growth and deformation of films directly and analyzing the influence of the deposition process and the plastic deformation behavior of films caused by parameters using computer simulation at the atomic scale this paper.In order to study the influence of the deposition process and the defect features of the bilayer films in the plastic deformation, we simulate the process of the deposition and the biaxial anisometry tensile deformation of the Ag/Cu(111), Cu/Ag(111) system by molecular dynamics method.In this paper, we have studied the influence of the deposition process of Cu/Ag bilayer films caused by each deposition parameter. The results show that it tends to be laminar growth in Ag/Cu(111) system while island growth in Cu/Ag(111) system. Increasing the deposition energy and substrate temperature can improve the surface quality. At the same time, the interface mixing degree is increased linearly and the stress changes from tensile stress to compressive stress. Substrate temperature plays an important role on surface quality when the deposition energy is low (< 4eV). Surface quality can be improved by decreasing the incident angle or increasing the deposition rate. The intermixing gets the minimum point. However, the intermixing gets strengthened either the deposition rate is too low or too high. The stress is small when the deposition rate is low while large when the deposition rate is high. And the stress is positive.In this paper, we have studied the influence of on Cu/Ag bilayer films, Cu films and Ag films caused, strain rate and temperature. It shows that the formation and development of dislocation appears firstly at the interface in the plastic deformation process of the Cu/Ag bilayer films. However, heterogeneous nuclei also can be observed at the interior or the free surface at high strain rate. Main defect types include partial dislocations, intrinsic stacking faults, extrinsic stacking fault and stacking-fault-tetrahedron, which can only be observed in the Cu layer and spreads towards the interface. Surface roughness gets the maximum point at the critical strain. Variation of the fraction of atoms in the stacking fault can be divided into five regions. The critical strain has the order: Cu/Ag bilayer films < Ag films < Cu films. High strain rate promotes the plastic deformation. The fraction of atoms in the stacking fault increases with the increasing of the strain while it reverses when the strain is low. The increasing of temperature promotes the plastic deformation but has no notable influence on the number of the stacking fault.