Role of solid solution strengthening on shock wave compression of [111] copper crystals

Abstract

The paper investigates the role of solid solution strengthening on the shock wave structure and Hugoniot elastic limit (HEL) in [111] copper crystals by molecular dynamics. Cu–Ni, Cu–Zn, Cu–Ag, and Cu–Al solid solutions are chosen to cover the range of atomic size misfit parameters for the solute atoms. The results show that in crystals with dislocations, the HEL decays slower with an increase in the misfit parameter of the solute, resulting in higher HEL values at a certain shock propagation distance. The Cu–Al solid solutions with the largest misfit parameter exhibit the largest deceleration of HEL decay. When the concentration of Al atoms increases to 20 at. %, the HEL almost does not change with shock propagation distance and a plateau shape of the elastic precursor is observed, as in the case of perfect crystals. In solid solutions without dislocations, the elastic precursor forms at lower velocities compared with perfect copper crystals, except for the Cu–20 at. % Ni solid solution. The HEL values increase with increasing misfit parameters and may take values lower than that for pure copper. These results show that the formation of the elastic precursor is facilitated by the presence of solid solution atoms, but the HEL magnitude and decay exponent are related to dislocation mobility in [111] copper crystals.