Molecular Dynamics Simulation Of The Extension Of Nano Wire And The Growth Of Nano Thin Film

Molecular dynamics (MD) is a rapidly developing method of molecular simulation. As a powerful method of nano scale simulation, it can be utilized to investigate the details of atomic movements and clarify experimental phenomena. It has been widely employed to calculate thermodynamic and dynamic properties as well as the structures of many systems. It has expansive exercising scope and appealing practical perspective. Processes of the extension of nano crystalline copper wire and the growth of Al Film on Cu surface have been simulated under three-dimensional molecular dynamics in this paper. The mechanical behavior of extension process, the effect of varied parameters of extension process, the growth mechanism of Al film on Cu (001) surface, and the influence of depositing atom energy to Al film growth are respectively studied in detail.The simulation results of the extension process of nano crystalline copper wire with varied parameters show that: The tension properties of copper nano wire are similar to those of macroscopic material. The stress increases linearly as the strain grows during the process of elastic deformation, and the dislocations and slips of structure lead to a stress oscillation during the process of plastic elongation. The effects of strain rate, temperature and other parameters on extension process are investigated thoroughly. The effect of strain rate is different in elastic deformation and plastic elongation. In elastic deformation, the effect depends on temperature (thermal motion): At OK, the strain rate will not affect the elastic; while above OK, its increasing will cause the raise of the elastic modulus and yield stress of nano wire. With the falling of temperature, the elastic modulus and tension yield stress increases. With the increasing of cross sectional area, the elastic modulus and tension yield stress increases. Considerable transformation of stress-strain curves will take place while the lattice orientation is different, and the yield strain is decided principally by lattice orientation.The simulation results of energetic atom deposition of thin Al film on Cu (001) surface indicate that: When the incident energy is low, the lattice structure of Al film generally matches substrate Cu (001) at the beginning, but as the film grows it will soon change to Al face-centered cube structure, growing along the <111> direction, and eventually form crystalline film. During the process, the film grows in the layer by layer model. With the increasing of incident energy, the substrate temperature increases and the structure of Al film becomes chaotic and less crystalline. Further increasing of incident energy will cause some Al atoms inject into Cu substrate and Cu atoms infiltrate into Al film which makes the film doped. High annealing can eliminate the defections of Al film or make the non-crystalline film crystalline. This method can be used to obtain high-quality crystalline films.