Calculations of diffusion in FCC binary alloys using on-the-fly kinetic Monte Carlo

We present a systematic, microscopic approach to diffusion for intermetallic alloys using accelerated molecular dynamics. On-the-fly kinetic Monte Carlo is combined with an efficient saddlepoint search to find the saddlepoints exiting a valley, based on energetics from the embedded atom method. With this technique, we compute the tracer diffusivities, migration energies, short-range order and long-range order as a function of composition and temperature for examples of moderately ordered (Cu3Au), weakly ordered (Au–Ag) and weakly clustered (Cu–Ni) alloys. We find that away from any critical temperature, the calculations produce reliable results, but when critical behavior dominates the approach is overcome by critical fluctuations.