106 / 2023-04-13 21:31:25

Shock waves and anisotropic deformation mechanisms in textured nanotwinned Cu

Nanotwinned Cu; Shock wave; Anisotropy; Dislocation; Texture

高压物理与材料科学 > 动高压-海报

In this paper, a model of nanotwinted copper with [111] texture was constructed, and the anisotropic response mechanism and microscopic deformation mechanism were investigated under the impact of 0.5km/s, 1km/s, 1.5km/s and 2.5km/s from 0°, 45° and 90° by molecular dynamics simulations. It is found that as the velocity increases, the correlation between the evolution characteristics of shock wave and the loading direction becomes smaller. Under the velocity of 0.5km/s, there are obvious secondary yield and two-stage plastic relaxation under 90° loading. When the velocity reaches 2.5km/s, the plastic wave velocity is higher than the elastic wave velocity in each loading direction. Under the shock wave, a secondary twin appears in the microstructure, and the original twin subsides. It is found that twin nucleation is closely related to dislocation motion, which leads to the following series of transformations: ISF→ESF→Twin→ESF→ISF. Furthermore, compared with 0° and 45° loading, the microstructure under 90° loading can maintain better under any velocity. The main reason for this difference is that the twin boundary impedes the dislocation motion. Then the atom motion mode under 0° shock wave is mainly migration, 45° is mainly rotation, and 90° is mainly slip. The interaction between the dislocation and the twin boundary leads to both plugging and proliferation of the dislocation, effectively improving material properties.