Planar superstructural defects in the alloys with L10 superstructure

Planar superstructural defects have a great influence on the mechanical, functional properties of binary ordered alloys of the L1₀ superstructure based on the fcc lattice, but there is no complete analysis of their structure and energy in the literature. For the L1₀ superstructure alloys of the stoichiometric composition AB, the paper gives the expressions for calculating the sublimation energy and the energy of a planar superstructural defect in the model of hard coordination spheres and pair interatomic interactions. The crystal lattice tetragonality was not taken into account. The authors presented the ordered alloy structure as a union of four monoatomic simple cubic lattices, two of which are occupied by A atoms, and the other two by B atoms. This approach allows calculating the sublimation energy required for crystal evaporation. The first eight coordination spheres were taken into account in the work. The paper shows an algorithm for determining all possible geometrically different representations of the L1₀ superstructure with the same sublimation energy, gives an expression for finding the planes of occurrence of all possible conservative antiphase boundaries. The study identified that the conservative and nonconservative antiphase boundaries, as well as conservative and nonconservative boundaries of C-domains are observed in the binary ordered alloys of the L1₀ superstructure based on the fcc lattice. The algorithms described in this work make it possible to carry out a crystal-geometric analysis of planar defects in both binary and multicomponent ordered alloys with various superstructures.