Multi-phase ELAStic Aggregates (MELASA) software tool for modeling anisotropic elastic properties of lamellar composites

We introduce a new web-based tool called MELASA (Multi-phase ELAStic Aggregates), open-access available at https://melasa.cerit-sc.cz, for computations and visualizations of anisotropic elastic properties of lamellar (nano-)composites. MELASA implements a linear-elasticity method by Grimsditch and Nizzoli (1986), originally developed for superlattices of any symmetry. Our tool may be used for computation of anisotropic elastic properties of a specific type of periodically separated lamellar (nano-)composites using matrices of elastic stiffnesses of co-existing phases as an input. Elastic properties are visualized in the form of directional dependencies of selected elastic characteristics (Young’s modulus and linear compressibility). MELASA further generalizes the Grimsditch–Nizzoli approach, which was originally formulated for only two phases, to multiple-phase composites. Additionally, our implementation allows for treating internal rotations of local coordination systems corresponding to the natural set of coordinates that match directional vectors of unit cell defining crystal lattice within the co-existing phases. Fe–Al-based superalloy nanocomposites are employed as a numerical example of superlattices with the input and output elastic stiffnesses determined by quantum-mechanical calculations. In particular, three different atomic configurations of interfaces in superlattices containing the ordered Fe_3 Al phase and a disordered Fe–Al phase with 18.75at.%Al (modeled by a special quasi-random structure, SQS) are considered. They differ by relative positions of sublattices in Fe_3 Al (an antiphase-like shift) and/or atomic planes in Fe-18.75at.%Al with respect to the interface (a circular/cyclic shift).