Monte Carlo simulation of simultaneous ordering and precipitation in BCC lattice

Fe-Al system quenched into its two-phase field undergoes a phase separation leading to the coexistence of A2 and B2 phases. Using transmission electron microscopy, three decomposition behaviour have been reported with increasing aluminium concentration: nucleation-growth of B2 inside a disordered matrix, decomposition of interconnected ordered phases which was attributed to spinodal decomposition, and nucleation-growth of A2 inside B2 domains. This work presents the first Monte Carlo simulations of simultaneous phase seperation and ordering in a two-phase A2/B2 domain. Calculations were performed using an Atomistic Kinetic Model; one vacancy allows atomic diffusion and a residence time algorthm is used. The three experimentally observed morphologies of evolution are reproduced. Moreover decomposition kinetics is compatible with the classical Lifeshits-Slyosow-Wagner coarsening thoery.