The effect of vacancies on grain-boundary segregation
in fcc ferromagnetic Ni
Martina Mazalová1
, Monika Všianská 1,2
, Jana Pavlů1
, Mojmír Šob 1,2,3
Affiliations:
1
Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, CZ-611 37 Brno,
Czech Republic
2
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22,
CZ-616 62 Brno, Czech Republic
3
Central European Institute of Technology, CEITEC MU, Masaryk University, Kamenice 5,
CZ-625 00 Brno, Czech Republic
This work presents a detailed ab initio study of interactions between grain boundaries (GB), impurities
X (X = Al, Si) and vacancies (Va) in fcc ferromagnetic nickel. As a basis of our calculations, supercells
containing 60 or 120 atoms, containing the tilt 5(210) GB, were used. The calculations were performed
within the density functional theory using the VASP code [1–3] with projector-augmented plane wave
(PAW) potentials [4, 5]. Two possible approaches to equilibration of structures (full relaxation and
relaxation with fixed lattice parameters in the GB plane) are presented and discussed.
The analyses of the following phenomena are provided: the influence of the lattice defects on structural
properties of material such as lattice parameters, the volume per atom, interlayer distances and atomic
positions; the energies of formation of particular structures with respect to the standard element
reference states; the stabilisation/destabilisation effects of impurities (in substitutional (s) as well as in
tetragonal (iT) and octahedral (iO) interstitial positions) and of vacancies in both the bulk material and
material with GBs; a possibility of recombination of Si(i)
-Va defect to Si(s)
one with respect to the Va
position; the total energy of formation of GB and Va; the binding energies between the lattice defects
and their combinations; impurity segregation energies and the effect of Va on them; magnetic
characteristics in presence of impurities, vacancies and GBs. As there is very little experimental
information on interaction between impurities, vacancies and GBs in fcc nickel, most of the present
results are theoretical predictions which may motivate future experimental work.
This research was supported by the Grant Agency of the Czech Republic (Project No. GA16-24711S), by
the Ministry of Education, Youth and Sports of the Czech Republic [Project CEITEC 2020 (LQ1601)] and
by the Academy of Sciences of the Czech Republic (Institutional Project No. RVO:68081723).
Computational resources were provided by the Ministry of Education, Youth and Sports of the Czech
Republic under the Projects CESNET (Project No. LM2015042), CERIT-Scientific Cloud (Project No.
LM2015085) and IT4Innovations National Supercomputing Center (Project No. LM2015070).
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