Effect of variation in inclination angle of Ʃ5 tilt grain boundary on the shock response of Ni bicrystals

Abstract

The intensity of damage production during shock wave propagation in polycrystalline metallic systems is mostly dependent on the shock-defect interactions. Traditionally, different coincidence site lattice (CSL) grain boundaries (GBs) are introduced in the polycrystalline structure through various processing techniques to enhance the strength or plasticity. However, their dynamic response to the impulsive loading condition has not been elaborately explored to date, which necessitates a detailed study on the interaction between CSL GBs and shock wave. In this study, we have employed molecular dynamics simulations to investigate the response of both symmetric and asymmetric ∑5[1 0 0] tilt GBs of nickel bicrystal under the influence of shock-wave. We have also analysed the role of piston velocities and inclination angles of the GBs on the shock response and the consequent deformation behaviour. This investigation gives insight into the mechanical response and the underlying mechanisms which are inspected through atomic strain analysis, common neighbour analysis and pressure–time–distance mapping. The results show that the stacking faults formation takes place when specimens are subjected to lower shock velocities, whereas higher velocities facilitate phase transformation along with amorphization. There is a stark contrast between the specimens with symmetric and asymmetric tilt GBs in the manner of plastic deformation behaviour in response to shock-wave and GB failure at lower and higher piston velocities.