QUANTUM-MECHANICAL STUDY OF MAGNETIC PROPERTIES OF SUPERALLOY NANOCOMPOSITE PHASE Fe2AlTi
| Autoři | |
|---|---|
| Rok publikování | 2018 |
| Druh | Článek ve sborníku |
| Konference | 9TH INTERNATIONAL CONFERENCE ON NANOMATERIALS - RESEARCH & APPLICATION (NANOCON 2017) |
| Fakulta / Pracoviště MU | |
| Citace | |
| Klíčová slova | Nanocomposites; Fe-Al based superalloys; ab initio calculations; fixed-spin-moment |
| Popis | 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 epsilon=-0.08 destabilizes the spin-polarized state, leaving the non-magnetic state as the only stable one. |
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