QUANTUM-MECHANICAL STUDY OF MAGNETIC PROPERTIES OF SUPERALLOY NANOCOMPOSITE PHASE FE2ALTI

1,2 SLÁVIK Anton
Co-authors:
1,2 MIHÁLIKOVÁ Ivana 1,2 FRIÁK Martin 1,3,4 VŠIANSKÁ Monika 1,3,4 ŠOB Mojmír
Institutions:
1 Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Brno, Czech Republic
2 Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic
3 Central European Institute of Technology, CEITEC MU, Masaryk University, Brno, Czech Republic
4 Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
Conference:
9th International Conference on Nanomaterials - Research & Application, Hotel Voronez I, Brno, Czech Republic, EU, October 18th - 20th 2017
Proceedings:
Proceedings 9th International Conference on Nanomaterials - Research & Application
Pages:
63-68
ISBN:
978-80-87294-81-9
ISSN:
2694-930X
Published:
8th March 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
35 views / 16 downloads
Abstract

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 ε=−0.08 destabilizes the spin-polarized state, leaving the non-magnetic state as the only stable one.

Keywords: Nanocomposites, Fe-Al based superalloys, ab initio calculations, fixed-spin-moment
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