Molecular Dynamics Simulations of Grain-Boundary Diffusion for Varying TILT Angle Geometries

The eeect of structure and geometry on grain boundary self-diiusion is investigated. Using static structures found by relaxation techniques (conjugate gradients) as starting points for a molecular dynamic simulation of a bicrystal model, diiusion coeecients and activation energies are calculated for (100) fcc Al and bcc-Fe tilt boundaries. These quantities are derived by monitoring the mean-squared displacement of atoms in the grain boundary region as the simulation progresses and as the temperature of the simulated solid is changed. The angular, directional, and structural dependence of the simulated diiusion are discussed and compared to experimental measures and theoretical predictions. The implementation of the molecular dynamics algorithm on a parallel supercomputer is also brieey discussed to illustrate the performance beneets these computers make possible.