Quantum-mechanical study of magnetic properties of superalloy nanocomposite phase Fe2AlTi

0493554 - ÚFM 2019 RIV CZ eng C - Konferenční příspěvek (zahraniční konf.)
Slávik, Anton - Miháliková, Ivana - Friák, Martin - Všianská, Monika - Šob, Mojmír
Quantum-mechanical study of magnetic properties of superalloy nanocomposite phase Fe2AlTi.
NANOCON 2017: Conference Proceedings. Ostrava: Tanger Ltd., 2018, s. 63-68. ISBN 978-80-87294-81-9.
[NANOCON 2017. International Conference on Nanomaterials - Research & Application /9./. Brno (CZ), 18.10.2017-20.10.2017]
Grant CEP: GA MŠMT LM2015069; GA ČR(CZ) GA17-22139S; GA ČR(CZ) GA16-24711S
Institucionální podpora: RVO:68081723
Klíčová slova: Ab initio calculations * Fe-Al based superalloys * Fixed-spin-moment * Nanocomposites
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)

The L21-structure Fe2AlTi intermetallic compound is one of the two phases identified in Fe-Al-Ti superalloy nanocomposites. Experimental data related to low-temperature magnetic properties of this Heusler compound indicate that magnetic moment is about 0.1 Bohr magneton per formula unit. In contrast, previous quantum-mechanical 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 quantum-mechanical fix-spin-moment calculations and compared our results with those for non-magnetic state. It turns out that the total energy of the non-magnetic 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 non-magnetic state appears at non-zero 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 compression-tension asymmetry with respect to these strains and, for example, the strain 0.08 destabilizes the spin-polarized state, leaving the non-magnetic state as the only stable one.
Trvalý link: http://hdl.handle.net/11104/0289458