
Quantummechanical study of magnetic properties of superalloy nanocomposite phase Fe2AlTi
Slávik, Anton ; Miháliková, Ivana ; Friák, Martin ; Všianská, Monika ; Šob, Mojmír
The L21structure Fe2AlTi intermetallic compound is one of the two phases identified in FeAlTi superalloy nanocomposites. Experimental data related to lowtemperature magnetic properties of this Heusler compound indicate that magnetic moment is about 0.1 Bohr magneton per formula unit. In contrast, previous quantummechanical calculations predicted Fe2AlTi to have much higher magnetic moment, 0.9 Bohr magneton per formula unit. In order to solve this discrepancy between the theory and experiment we have performed a series of quantummechanical fixspinmoment calculations and compared our results with those for nonmagnetic state. It turns out that the total energy of the nonmagnetic state is only by 10.73 meV/atom higher than that of the magnetic state. When applying Boltzmann statistics to this very small energy difference we predict that the nonmagnetic state appears at nonzero temperatures with significant probabilities (for instance, 22.36 % at T = 100 K) and reduces the overall magnetic moment. As another mechanism lowering the magnetization we studied selected shape deformations, in particular trigonal shearing. Fe2AlTi exhibits a compressiontension asymmetry with respect to these strains and, for example, the strain 0.08 destabilizes the spinpolarized state, leaving the nonmagnetic state as the only stable one.


Theoryguided design of novel FeAlbased superalloys
Friák, Martin ; Holec, D. ; Jirásková, Yvonna ; Palm, M. ; Stein, F. ; Janičkovič, D. ; Pizúrová, Naděžda ; Dymáček, Petr ; Dobeš, Ferdinand ; Šesták, Pavel ; Fikar, Jan ; Šremr, Jiří ; Nechvátal, Luděk ; Oweisová, S. ; Homola, V. ; Titov, Andrii ; Slávik, Ondrej ; Miháliková, Ivana ; Pavlů, Jana ; Buršíková, V. ; Neugebauer, J. ; Boutur, D. ; Lapusta, Y. ; Šob, Mojmír
Our modern industrialized society increasingly requires new structural materials\nfor hightemperature applications in automotive and energyproducing industrial\nsectors. Ironaluminides are known to possess excellent oxidation and sulfidation\nresistance as well as sufficient strength at elevated temperatures. New FeAlbased\nmaterials will have to meet multiple casting, processing and operational criteria\nincluding hightemperature creep strength, oxidation resistance and roomtemperature\nductility. Such desirable combination of materials properties can be achieved in multiphase\nmulticomponent superalloys with a specific type of microstructure (the matrix contains\ncoherent particles of a secondary phase  a superalloy microstructure). In order to design\nnew FeAlbased superalloys, we employ a stateoftheart theoryguided materials design\nconcept to identify suitable combinations of solutes.
