Abstract In this paper, perfect interface model of Al/AlCu alloy and defect interface model of Al/AlCu alloy after cracks were introduced at different positions of the interface were established by using cohesive zone modeling method. Classical molecular dynamics simulation was used to study the deformation behavior and microstructure evolution of Al/AlCu alloy interface model at a strain rate of 0.05 Å/ps and the temperature of 300 K. The simulation results show that perfect interface exhibits a uniform plastic deformation stage due to structural relaxation after yielding, while there is no structural relaxation during the deformation of defect interface and the tensile strength is much lower than that of perfect interface as well. In the process of deformation, stacking faults formed in perfect interface and cracks are generated and expanded in Al matrix, while there was no stacking faults forming along with the expansion and cracking at the position of introduced cracks in defect interface. Massive dislocation nucleation leads to the reduction in stress at the perfect and defect interfaces after yielding. The extension of Shockley partial dislocation and the nucleation of Stair-rod dislocation are the main mechanisms of interface deformation. Densities of Shockley partial dislocation and Stair-rod dislocation decrease with increasing strain before crack propagation. This study enriches the analysis of microstructure evolution of Al/AlCu alloy interface and similar interfaces during deformation.
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