Simulation methods were developed in order to study the role which interactions among defects and diffusants, and local association effects, played in diffusion in metals. The impurity diffusion of Fe in Al was used as an example. Using recently developed accurate interatomic potentials for the Fe-Al system, migration energies for atom-vacancy exchange in a variety of local atomic configurations were calculated by using lattice statics methods. These were used, in a kinetic Monte-Carlo framework, to calculate diffusivities. Two different activation regimes were observed, above and below 550K. This anomalous non-Arrhenius behavior of the diffusion activation energy was explained in terms of the interaction among vacancies and Fe atoms, and local association/ordering effects.

Anomalous Diffusion in Dilute Solid Solutions. R.Krishnamurthy, D.J.Srolovitz, M.I.Mendelev: Acta Materialia, 2007, 55[15], 5289-96