Role of grain architecture in shock behavior and spalling behavior of Al metal-\(\text {Al}_{90}\text {Sm}_{10}\) metallic glass nanolaminates

Molecular-dynamics-based simulations have been carried out for crystalline Al-\(\text {Al}_{90}\text {Sm}_{10}\) metallic glass (MG) nanolaminates with different grain structures corresponding to varying values of shock intensities to analyze the structural evolution during shock-wave loading and spallation behavior of the nanolaminates. A transition from elastic–plastic behavior occurs in nanocrystalline NC-MG nanolaminates with increasing values of shock intensities when the shock traverses from the crystalline end to the MG end. On the other hand, an overdriven elastic front is observed for all values of shock intensities in columnar-grained CG-MG nanolaminates. When the shock-wave direction is reversed, a plastic wave dominates the shock profiles irrespective of the grain structures and shock intensity values. Adaptive common neighbor analysis (a-CNA) and dislocation analysis reveal that grain boundary-mediated plasticity is dominant in NC-MG nanolaminate specimens, while dislocation-mediated plasticity predominately governs the shock deformation behavior in CG-MG nanolaminates. The reflection of the rarefaction wave generated at the crystalline–amorphous interface aids in stacking fault generation in NC-MG nanolaminates but does not cause any structural changes in CG-MG nanolaminates. The spallation behavior of the nanolaminate specimens is significantly influenced by the grain structures and the presence of the free surfaces. The population of perfect icosahedral clusters \(\langle 0\,0\,12\,0\rangle \) decreases during the passage of shock as determined using Voronoi cluster analysis.