The investigation of the structure of binary and multicomponent crystal systems during their growth from various mother phases occupies an important place in modern materials science. This particularly concerns the problems of ordering of stoichiometric binary metal crystals with a simple cubic lattice during their growth from binary vapor-gas mixtures or equimolar binary melts. Of special interest are the cases in which binary crystals grow at temperatures that are much lower than the Curie temperature T C , where, according to classical thermodynamics, a binary crystalline phase that is totally ordered in composition should form. However, under certain crystallization conditions (in the case of fast deviation from the equilibrium temperatures of the (vapor-gas mixture)-crystal system or the melt-crystal system) and because of the low mobility of particles (growth monomers) in the crystalline phase, a crystal matrix that is completely disordered in composition may form. In other words, if the cooperative interaction of particles of different sorts at crystal lattice sites is taken into account, the chaos of a binary vapor-gas mixture or a binary melt may be preserved in the crystalline state. The order-disorder transition in binary crystals is accompanied by singularities in the kinetics of crystallization of binary systems; namely, the average crystallization rate versus temperature plot has a kink at the disordering point (at the critical temperature T d < T C ). Therefore, with an increase in the supercooling of a crystallizing system, the average crystallization rate increases much more slowly.
EFFECT OF THE MORPHOLOGY OF THE MOTHER PHASE-CRYSTAL INTERFACE ON THE DISORDERING OF STOICHIOMETRIC BINARY CRYSTALS WITH A SIMPLE CUBICLATTICE The effect of the morphology of the interface between the contacting binary phases (in the (vaporgas mixture)-crystal system or the binary metal meltcrystal system) on the disordering and its related kinetic phenomena was noted for the first time by Chistyakov and colleagues [1,2]. In these works, in considering the growth of binary crystals from equimolar binary melts and binary vapor-gas mixtures, the morphology of the interface was described by the Kossel-Stranski crystal surface model. This is a simplified model since it assumes that, at the interface, there is only a single rough step with many indentations of different sizes on the step riser (Fig. 1). This model allows the exchange of growth monomers (particles of different sorts) between the contacting phases (the liquid and the crystal or the vapor-gas mixture and the crystal) only at the indentations on the riser of the only step, which is undoubtedly too great a simplification of real crystallization. Nonetheless, it was found [1, 2] that the topological singularity of the Kossel rough crystal step leads to the fact that, regardless of the aggregation composition of the mother phase, the disordering of binary crystals occurs identically: at the disordering temperature T d < T C , the long-range order parameter η appr...