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 ki netics in B2 phases is now applied to the calculation of phase diagram s 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 m echanism, lies on an Ising Hamiltonian with interaction energies betwe en first and second nearest neighbors. The simulations reproduce exper imental trends for the activation energy of the self-diffusion in equi atomic FeCo and for the migration energy in Fe3Al and Fe3Si compounds. Critical slowing-down of the relaxation times are observed al the ord er-disorder transitions, in qualitative agreement with experimental re sults in Fe3Al. (C) 1997 Elsevier Science S.A.