Atomistic simulation of the atomic structure and diffusion within the core region of an edge dislocation in aluminum

Abstract

The core structure of an edge dislocation in aluminum is studied by molecular dynamics simulation with the glue potential. The edge dislocation of the $\frac{1}{2}[1\ifmmode\bar\else\textasciimacron\fi{}10](111)$ type is observed to dissociate into two partials separating from each other by a distance of 9 \AA{}. The half width of the two partial dislocations is deduced to be 6.5 \AA{}, giving a half width of the whole dislocation of 12 \AA{}. Dislocation mobility is studied by applying a shear stress on the crystal and by observing the corresponding shift of the Burgers vector density. After considering the mirror force on the dislocation exerted by the fixed boundaries, a Peierls stress of $0.75\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\ensuremath{\mu}$ (\ensuremath{\mu} is the shear modulus) for the motion of the whole dislocation is obtained. Atomic diffusion in the core region of the edge dislocation is simulated by hyper molecular dynamics method and the migration energy for vacancy diffusing in the dislocation core is calculated to approximate 0.5 eV.