Quantum-Mechanical Study of Nanocomposites with\nLow and Ultra-Low Interface Energies

0498985 - ÚFM 2019 RIV CH eng J - Journal Article
Friák, Martin - Holec, D. - Šob, Mojmír
Quantum-Mechanical Study of Nanocomposites with
Low and Ultra-Low Interface Energies.
Nanomaterials. Roč. 8, č. 12 (2018), č. článku 1057. E-ISSN 2079-4991
R&D Projects: GA ČR(CZ) GA16-24711S; GA ČR(CZ) GA17-22139S
Institutional support: RVO:68081723
Keywords : MoSi2 * WSi2 * TaSi2 * NbSi2 * elasticity * ab initio * interface energies * Fe3Al * disorder
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 4.034, year: 2018

We applied first-principles electronic structure calculations to study structural,
thermodynamic and elastic properties of nanocomposites exhibiting nearly perfect match of
constituting phases. In particular, two combinations of transition-metal disilicides and one pair
of magnetic phases containing the Fe and Al atoms with different atomic ordering were considered.
Regarding the disilicides, nanocomposites MoSi2/WSi2 with constituents crystallizing in the
tetragonal C11b structure and TaSi2/NbSi2 with individual phases crystallizing in the hexagonal
C40 structure were simulated. Constituents within each pair of materials exhibit very similar
structural and elastic properties and for their nanocomposites we obtained ultra-low (nearly zero)
interface energy (within the error bar of our calculations, i.e., about 0.005 J/m2). The interface
energy was found to be nearly independent on the width of individual constituents within the
nanocomposites and/or crystallographic orientation of the interfaces. As far as the nanocomposites
containing Fe and Al were concerned, we simulated coherent superlattices formed by an ordered
Fe3Al intermetallic compound and a disordered Fe-Al phase with 18.75 at.% Al, the a-phase. Both
phases were structurally and elastically quite similar but the disordered a-phase lacked a long-range
periodicity. To determine the interface energy in these nanocomposites, we simulated seven different
distributions of atoms in the a-phase interfacing the Fe3Al intermetallic compound. The resulting
interface energies ranged from ultra low to low values, i.e., from 0.005 to 0.139 J/m2. The impact of
atomic distribution on the elastic properties was found insignificant but local magnetic moments of
the iron atoms depend sensitively on the type and distribution of surrounding atoms.
Permanent Link: http://hdl.handle.net/11104/0293614