Molecular dynamics simulations of 45° [100] twist plus tilt grain boundaries in aluminum

Abstract

High-resolution electron microscopy has been used to study a [100] 45° twist/17.5° tilt grain boundary in aluminum. This mixed-type aperiodic boundary is characterized by two fundamental structural units. Each of these two units is a basic building block for the 45° twist/13.29° tilt and 45° twist/19.47° tilt grain boundaries, respectively. Molecular dynamics simulations of bicrystals with the above two misorientations have been performed. Interatomic forces between aluminum atoms have been modelled by the use of density-dependent pseudopotentials. A new type of boundary condition has been used to allow for translational relaxation at the interface. The results presented here show that the observed structural units are stable, with some relaxation occurring at the grain boundary core.