Investigation on void growth and coalescence in single crystal copper under high-strain-rate tensile loading by atomistic simulation

摘要

The failure mechanism of ductile metals is dominated by the nucleation, growth and coalescence of voids, and it is important to capture the evolution of voids on nanoscale. More than ten atomic models, each containing about 10 million atoms, are simulated under tensile loading at strain rate 5 x 10(8) s(-1). The influences of two parameters, the initial radius and the initial spacing of two voids, are also investigated in detail. The increment in void fraction increases linearly with strain at the last stage of void evolution, and the increment has little relation with initial radius and spacing of voids in this stage. The peak value of stress triaxiality increases first with the initial intervoid ligament distance until it reaches the critical point of void coalescence, and then decreases. It suggests that stress triaxiality may be an important indicator to characterize whether the void coalescence will occur. Dislocation analysis shows that the dislocation emissions from void surface is an important behavior in the initial stage of void evolution, but it has little effect on the void volume in the cases studied.