The diffusion process in a A-B binary alloy with B2 order was studied by atomistic Monte Carlo simulations using a vacancy mechanism. The chosen ordering energies were taken from neutron scattering experiments and ensure a phase diagram close to that of the real Fe-Al system. The dynamics was introduced by one single vacancy jumping to nearest-neighbor sites. Employing different jump-energy evaluations for the exchange vacancy and atom, diffusion constants were determined as a function of temperature and the mobility of antiphase boundaries was investigated. While the different jump-energy evaluations yielded a similar behavior of the diffusion constant above Tc, a more complex influence of the evaluation on the diffusion constant below Tc was found. Finally, the autocorrelation function of the atoms was calculated and compared with measurements on Fe50Al50 done by quasielastic Mössbauer spectroscopy. A similarity between the simulated and the experimentally obtained autocorrelation function was observed despite the simplicity of the jump model used.

Monte Carlo Simulation of Diffusion in a B2-Ordered Model Alloy. R.Weinkamer, P.Fratzl, B.Sepiol, G.Vogl: Physical Review B, 1998, 58[6], 3082-8