Molecular Dynamics Simulation Of Interface Bonding And Tensile Properties Of Cu/Al Casting

Since the industrial revolution,the development of the three times industrial revolutions has brought the research of materials into the nanometer era,and high-precision instruments such as micro-nano electromechanical systems(MEMS/NEMS)have come out one after another.With the increase of system integration,electronic integrated circuits and electronic chips have become more and more functional,but the requirements for device size are becoming smaller and smaller.At present,the line width of large-scale integrated circuits has reached 70 nm,which puts forward higher requirements for the properties of materials.Limited by the space size of devices,the materials in integrated electronic circuits,MEMS/NEMS and other devices mainly exist in the form of nano-film.Cu/Al multilayer films have excellent physical and chemical properties of copper and aluminum,which are often used in aerospace and microelectronics fields,and the mechanical properties of Cu/Al multilayer films are important indicators of practical application.In this paper,the diffusion process and mechanical properties of Cu/Al multilayers at different casting temperature and casting time were studied by molecular dynamics method,and the effect of space size(modulation period and modulation ratio)on the mechanical properties of Cu/Al multilayers was studied,the results show:With the increase of casting time and casting temperature,the number of copper and aluminum atoms diffuses,and the number of copper atoms diffuses to the aluminum side is more than that of the aluminum atom to the copper side.With the increase of casting temperature,the diffusion coefficient of copper and aluminum atoms increases,the diffusion coefficient of copper is greater than that of aluminum,and the thickness of transition layer in interface zone increases continuously,which leads to the change of mechanical properties of Cu/Al multilayer film,the tensile strength increases first and then decreases with the increase of casting temperature,and at casting temperature 1013 K,the tensile strength reaches the maximum value of4.02 GPa.With the increase of casting time,the thickness of Cu/Al multilayer film transition layer increases,the tensile strength and the tensile strain increases first and then decreases gradually.The tensile strength reaches the maximum value of 4.02 GPa at 0.2 ns,and the mechanical properties of multilayer film are best when holding0.2 ns at 1013 K.By comparing the atomic structure of the plastic deformation stage of Cu/Al multilayer films at different casting time,the results show that when the casting time is 0.2 ns,the formation of stacking fault,twin and multi-layer HCP structure and the increase of their number make the strength and plasticity of the film increase.When the casting time is more than 0.5 ns,the material structure changes because the casting time is too long and the diffusion number of copper and aluminum atoms is too much.The bonding strength of Cu/Al multilayers decreased.The uniaxial tensile results of Cu/Al multilayer films under different modulation periods and modulation ratios show that: There are obvious size effects on the yield strength,tensile strength,yield strain and tensile strain of Cu/Al multilayers.The yield strength first increases and then decreases with the increase of modulation period of Cu/Al multilayers,and reaches the maximum value when the modulation period is 14 nm,while the tensile strength first decreases and then increases with the increase of modulation period,and the tensile strength is the smallest when the modulation period is 20 nm.The variation trend of yield strain and tensile strain is the same as that of yield strength and tensile strength,respectively.When the modulation period is 20 nm,the results of the modulation ratio study on the Cu/Al multilayer film show that the yield strength of the multilayer film increases with the increase of the modulation ratio.When ? ? 1/2,the yield strain increases with the increase of modulation ratio,when ??1/2,the yield strain decreases slightly at ?=2 and remains basically unchanged at other times;both tensile strength and tensile strain decrease first and then increase with the increase of modulation ratio,and at ?=1,both tensile strength and tensile strain reach the minimum value.