Computational and experimental study of the effect of the composition on the morphology of the ordered domains and APBs structures

The formation and growth of ordered domains in Fe–Al alloys is explored computationally in two-dimensions (2D) using the modified Khachaturyan diffusion equation by utilizing the thermodynamic parameters related to the equilibrium phase diagram and experimentally by using a single sample containing a steep composition gradient. The effect of alloy composition on the morphology of the ordered domains as well as the APBs in a single phase is presented. Experiment and computer simulations show that the time to form an ordered structure increases rapidly as the composition approaches the order–disorder transition line. Moreover, diffuse APBs are found to be formed near the transition line. The early stage of ordering is also described.