Regensburg 2022 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 20: Computational Materials Modelling: HEA, Alloys & Nanostructures
MM 20.6: Talk
Wednesday, September 7, 2022, 11:45–12:00, H44
Phase stability and formation energies of stacking faults in intermetallic MgxAl2−xCa Laves phases — •Ali Tehranchi, Tilmann Hickel, and Jörg Neugebauer — Max Planck institute for Iron research, Max Planck Straße 1, 40237 Düsseldorf
The intermetallic Laves phases that form in Mg-based alloys at higher alloying concentrations have a significant impact on their mechanical properties. For example, they can enhance the creep resistance of the alloys and extend their application to higher temperature domains. However, the mechanisms of deformation of these phases are not fully understood. In this work, at first the formation energies of the different realizations of C14, C15, and C36 Laves phases in the composition domain, MgxAl2−x with 0<x<2, using the ab initio simulations is calculated. Using these formation energies, the phase diagram of the phases of interest is constructed. The effect of the strain fields on the relative stability of these phases is included. In addition, using the analytic Axial Next-Nearest Neighbor Ising (ANNNI) type model, the basal stacking faults in each phase and composition are calculated. The results of the analytic models are in good accordance with the results of the direct DFT simulations of the stoichiometric stacking faults. The gamma surface of certain realizations of the C36 phase is also investigated and explain the experimentally observed planar defects in the C36 phase.