Shock-induced sliding of (0 0 1) twist grain boundaries in Cu

Using molecular dynamics simulations, we investigate shock-induced sliding of a set of (0 0 1) twist grain boundaries (GBs) in Cu bicrystal, with shock direction parallel to GB and low shock strength. The GB sliding is produced via transverse particle motion in constituent grains and resisted by GB viscosity. Its utmost magnitude su increases first and then decreases with increasing of the angle between [1 0 0] direction in grain and shock direction. Quantitative acoustic wave equation analysis reveals that transverse particle motion exists because of the anisotropic elastic stiffness and particular grain orientation. For GBs of noteworthy sliding, boundary viscosity η is estimated according to the deceleration of volume element in grain, and decreases piecewisely with increasing misorientation angle. su is jointly determined by η and transverse particle velocity dependent on grain orientation