Study On Interface Diffusion Mechanism Of Cu/Al Solid-liquid Vibration Casting-rolling Composite Process Based On Molecular Dynamics Simulation

Cu/Al composite material combines copper with high electrical and thermal conductivity and low contact resistance with light and economical aluminum,so that copper and aluminum can complement each other in cost and performance,and achieve the goal of saving copper with aluminum.It is widely used in aerospace,power electronics and other fields.Since the structure and performance of the composite interface have a greater impact on the overall performance of the composite material,how to effectively control the thickness of the composite interface layer and the type,quantity and morphology of the brittle phase in the interface layer is the guide for the development of new composite technologies and new processes today.There is an urgent need to explore the nature of Cu/Al interface bonding and the microscopic deformation mechanism of the interface.Based on the Cu/Al solid-liquid composite casting-rolling process,our team proposed the Cu/Al solid-liquid vibration composite casting-rolling process.On the one hand,the process has two conditions for promoting the metallurgical bonding of the interface at high temperature and high pressure.At the same time,it can also apply vibration to the molten pool through the slight up and down movement of the roll to strengthen the physical metallurgical bonding of the composite interface.In this paper,relying on the Cu/Al solid-liquid vibration composite casting-rolling process,molecular dynamics simulation methods are used to study the two problems of Cu/Al interface diffusion characteristics and Cu/Al interface deformation behavior at the atomic scale.First,based on the molecular dynamics simulation method,a Cu/Al solid-liquid diffusion model was established,and the effect of diffusion time on the Cu/Al interface diffusion at high temperature was studied.Then,a cooling simulation was performed on the molecular dynamics model of long-term diffusion at high temperature,and the changes of the diffusion coefficients of Cu and Al atoms during the solidification of molten aluminum were obtained,and the changes in the thickness of the interface layer during the solidification and Cu,The diffusion behavior of Al atoms was characterized,and the influence of liquid aluminum solidification on interface diffusion was summarized.Secondly,the plastic deformation process of Cu/Al interface system and Cu/Al diffusion interface system under compressive load is simulated and analyzed.The results show that interface diffusion will increase the compressive strength of the copper-aluminum composite interface.Under compressive load,the diffusion interface layer will first undergo brittle fracture,forming a complex stacking fault structure and dislocation packing,which will have a profound impact on subsequent deformation.Finally,the plastic deformation process of the Cu/Al diffusion interface system under the combined compression-cyclic shear load is simulated,and the plastic deformation process of the system under different shear amplitudes and shear frequencies is compared and analyzed.The results show that increasing the shear amplitude and shear frequency can reduce the normal stress value of the system and improve the compressive plasticity of the diffusion interface.The addition of shear strain can accelerate the fracture of the diffusion interface layer and destroy the hardened structure produced in the diffusion interface layer.,Causing continuous changes in the stacking fault structure in the diffusion interface layer,the greater the shear amplitude and the higher the shear frequency,the more obvious this phenomenon.