A Kinetic Monte Carlo Simulation of Ordering Process in Ti-Al System

We perform kinetic Monte Carlo simulations of atomic diffusion in the Ti-Al system using activation energies calculated by embedded atom method (EAM). The activation energies strongly depend on the atomic species occupying the four atomic sites which locate nearest to the saddle point in the fee lattice. It is found, however, that the configuration of atoms on the other sites surrounding the jumping atom plays an essential role in the atomic ordering process: we fail to reproduce the formation of ordered nuclei in using the activation energies which depend only on the configuration of the nearest four atoms, and the system remains in disordered states even at very low temperatures. By introducing a correction term to the activation energies which takes into account the contribution of nearest neighbor atoms of the migrating atom, we can simulate growth of ordered embrios.