Kinetics of L1(0)-type and L1(2)-type orderings in alloys at early stages of phase transformations

We study the kinetics of the L1(0) ordering in face-centred alloys at early stages of phase transformations, when the tetragonal distortion of the L1( 0) phase is still insignificant as regards the microstructural evolution, a nd compare it with the kinetics of the L1(2) ordering. We use the earlier-d escribed kinetic cluster-field method to simulate A1 --> L1(0) and A1 --> L 1(2) transformations after a quench of an alloy from the disordered Al phas e to the single-phase L1(0) or L1(2) state for a number of alloy models wit h both short-range and extended-range interactions. The simulations reveal a number of peculiar features in both transient microstructures and transfo rmation kinetics-in particular, a sharp dependence of the microstructural e volution and the structure of antiphase boundaries under the L1(0) ordering on the composition of the alloy; the importance for both the L1(0) and L1( 2) ordering of a peculiar mechanism of domain growth via the fusion of diff erent in-phase domains; the presence in transient microstructures under the L1(0) ordering of some specific long-living configurations, quadruple junc tions of four different antiphase domains, as well as of peculiar kinetic p rocesses of 'splitting' of certain antiphase boundaries into two others; an d other features.