Ordering kinetics in DO3 and B2 intermetallic compounds: comparison between Monte Carlo simulations and experiments

The Monte Carlo model previously developed to simulate the ordering kinetics in B2 phases is now applied to the calculation of phase diagrams that display DO3 and B2 structures and to that of the relaxation of the long range order parameters in DO3 and B2 phases and at the DO3–B2 and DO3–A2 transitions. The model, which is based on a vacancy jump mechanism, lies on an Ising Hamiltonian with interaction energies between first and second nearest neighbors. The simulations reproduce experimental trends for the activation energy of the self-diffusion in equiatomic FeCo and for the migration energy in Fe3Al and Fe3Si compounds. Critical slowing-down of the relaxation times are observed at the order–disorder transitions, in qualitative agreement with experimental results in Fe3Al.