Molecular Dynamics Simulation Of Interfacial Atoms Diffusion At The Interface Of Hot Rolling-diffusion Bonding Cu/Al

Production of metal composite materials has been successfully applied in industrial production for many years by rolling compound. However, how to scientifically reveal the complex interaction between the metal interface is a major concern for a long time. In recent years, molecular dynamics method was used to study the mechanism of composite has made a significant progress.In this paper, the molecular dynamics method based on general embedded atom method potential function (GEAM) was used to simulate the impact of temperature and pressure on diffusion of interfacial atoms during the diffusion bonding process. The diffusion of atoms on the interface was calculated in the atomic scale. The diffusion coefficient of copper atoms and aluminum atoms was calculated by Einstein diffusion law when temperatures at 400K,500K,700K and 800K respectively. The diffusion coefficient at the temperatures of 800K are 4.83×10-9m2/s and 1.85×10-11m2/s, two orders of magnitude smaller than the value of 400K or 500K. The interface diffusion activation energy of the aluminum atoms and copper atoms are QAl=0.33eV and QCu=0.53eV, Arrhenius relations were used. The simulation result also indicated that the diffusion process of copper and aluminum composite at low temperature is not clear, but atoms in the 800K were occurring at the interface diffusion. And, copper atoms diffuse into the layer of aluminum atoms mainly, only a small amount of aluminum atoms diffuse into the layer of copper atoms. The diffusion activation energy of the interfacial atoms is small than diffusion activation energy of atoms within crystal. And rolling pressure is conducive the improvement of the diffusion of the interface. When the applied pressure of 10MPa to 15MPa, the interface diffusion slight improvement, and when the pressure increased to 20MPa, the interface atomic diffusion more obvious. Finally we calculated by the concentration of the diffusion layer was informed that, dynamics of time 100ps, the aluminum atoms in the copper side of the transition layer is the proportion of 8.9at%, did not reach the solubility of Al in Cu 19.7at% when the temperature is 800K. So sufficient holding time is also play a very good role on the interface diffusion.