Atomistic simulations of shock induced melting of bicrystal copper with twist grain boundary

We investigate the shock induced melting of Cu bicrystals with [001] twist grain boundary (GB) under various shock intensities using atomistic dynamics simulations. Two representative types of twist GBs are studied: 5 / (001) / 36.87°and 181 / (001) / 6.03°with relatively high and low GB energies, respectively. The properties of the shocked GB region evolving with time are characterized in terms of order parameters and mean-squared displacement. In the case of 5 / (001) / 36.87°, it is found that prior to the homogeneous melting of the whole sample, continuous partial melting with considerable premelting of the shocked GB region precedes bulk melting with negligible superheating of GB, while solid state disordering may precede the partial melting. In contrast, for 181 / (001) / 6.03°, the melting process is analogous to that of a shocked perfect crystal except that a limited superheated partial melting state occurs before homogeneous melting of the whole bicrystal.