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Trybula, M. E. & Korzhavyi, P. . (2019). Atomistic Simulations of Al(100) and Al(111) Surface Oxidation: Chemical and Topological Aspects of the Oxide Structure. The Journal of Physical Chemistry C, 123(1), 334-346
Open this publication in new window or tab >>Atomistic Simulations of Al(100) and Al(111) Surface Oxidation: Chemical and Topological Aspects of the Oxide Structure
2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 1, p. 334-346Article in journal (Refereed) Published
Abstract [en]

The chemical and topological aspects of short- and medium-range atomic ordering on oxidized Al(100) and Al(111) surfaces have been studied by employing reactive force field-based molecular dynamics (ReaxFF-MD) simulations as a function of O-2 gas density at 300 K. We found two oxide film growth regimes, compatible with experimental and recent modeling data. Trend of changes in oxide film thickness with increasing oxygen gas density agrees with available literature data, while slightly thicker oxide film forms on the Al(100) substrate. Chemical descriptors of short- and medium-range correlation manifest difference in atom environment between two ultrathin oxide films as Al-[3,Al-4] and O-[2,O-3]-coordinated species dominate. In turn, a highly liquid-like structure of ultrathin oxide film develops on the Al(100) surface compared to an amorphous nature of the Al(111) oxide film with slightly lower thickness. Three-dimensional analysis of oxide structures reveals a medium-range atomic order formed by the arrangement of dominating corner-sharing configurations over edge-sharing ones with some deviation from the ideal polyhedral units. Three-fold ring is in majority over 2-, 4-, and 5-fold ones, in conjunction with a 2-fold ring forming the most frequent ring linkage. The high-n ring structure can be treated as a measure of a certain degree of "free volume", incorporated in the oxide film during its growth on the Al(100) or Al(111) surfaces and can initiate nanostructure formation in anodic oxide film. Such diversity in ring abundance also explains the lower mass density of the oxide films compared to crystalline alumina compounds.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-242978 (URN)10.1021/acs.jpcc.8b06910 (DOI)000455561100035 ()2-s2.0-85059390617 (Scopus ID)
Funder
Carl Tryggers foundation , CTS 2016:253Swedish Foundation for Strategic Research , RMA11-0090
Note

QC 20190204

Available from: 2019-02-04 Created: 2019-02-04 Last updated: 2019-02-04Bibliographically approved
Zhandun, V., Zamkova, N., Korzhavyi, P. . & Sandalov, I. (2019). Inducing magnetism in non-magnetic alpha-FeSi2 by distortions and/or intercalations. Physical Chemistry, Chemical Physics - PCCP, 21(25), 13835-13846
Open this publication in new window or tab >>Inducing magnetism in non-magnetic alpha-FeSi2 by distortions and/or intercalations
2019 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 25, p. 13835-13846Article in journal (Refereed) Published
Abstract [en]

By means of hybrid ab initio + model approach we show that the lattice distortions in non-magnetic alpha-FeSi2 can induce a magnetic state. However, we find that the distortions required for the appearance of magnetism in non-magnetic alpha-FeSi2 are too large to be achieved by experimental fabrication of thin films. For this reason we suggest a novel way to introduce magnetism in alpha-FeSi2 using "chemical pressure" that is, intercalating the alpha-FeSi2 films by light elements. Theoretical study of the distortions resulting from intercalation reveals that the most efficient intercalants for formation of magnetism and a high spin polarization are lithium, phosphorus and oxygen. Investigation of the dependency of the magnetic moments and spin polarisation on the intercalation atoms concentration shows that the spin polarization remains high even at small concentrations of intercalated atoms, which is extremely important for modern silicate technology.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-255408 (URN)10.1039/c9cp02361e (DOI)000473056500040 ()31211304 (PubMedID)2-s2.0-85068369423 (Scopus ID)
Note

QC 20190814

Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-14Bibliographically approved
Kar'kin, I. N., Kar'kina, L. E., Gornostyrev, Y. N. N. & Korzhavyi, P. . (2019). Kinetics of Early Decomposition Stages in Diluted bcc Fe-Cu-Ni-Al Alloy: MC plus MD Simulation. Physics of the solid state, 61(4), 601-608
Open this publication in new window or tab >>Kinetics of Early Decomposition Stages in Diluted bcc Fe-Cu-Ni-Al Alloy: MC plus MD Simulation
2019 (English)In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 61, no 4, p. 601-608Article in journal (Refereed) Published
Abstract [en]

A combined approach including the Monte Carlo and molecular-dynamics simulation, decomposition kinetics and segregation formation in the multicomponent low-alloy Fe-1.5Cu-2Ni-1.5Al (at %) alloy is studied. It is shown that the formation of Cu nanoparticles surface-enriched with Ni and Al (coprecipitation mode) includes several stages: (i) the formation of clusters consisting of several Cu atoms, (ii) their enrichment with Ni and Al atoms, and (iii) redistribution of Ni and Al atoms with the formation of a surface layer providing stabilization of Cu nanoparticles. Observed structural features of segregations and their stability in Fe-Cu-Ni-Al alloys is discussed.

Place, publisher, year, edition, pages
PLEIADES PUBLISHING INC, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-252651 (URN)10.1134/S1063783419040152 (DOI)000467502200018 ()2-s2.0-85065496396 (Scopus ID)
Note

QC 20190610

Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-10Bibliographically approved
Chen, K. X., Korzhavyi, P. ., Demange, G., Zapolsky, H., Patte, R., Boisse, J. & Wang, Z. D. (2019). Morphological instability of iron-rich precipitates in Cu-Fe-Co alloys. Acta Materialia, 163, 55-67
Open this publication in new window or tab >>Morphological instability of iron-rich precipitates in Cu-Fe-Co alloys
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2019 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 163, p. 55-67Article in journal (Refereed) Published
Abstract [en]

The mechanical properties of metallic materials are determined by their microstructure, and in particular, the different morphologies of precipitates lead to distinct strengthening effects. Usually, the shape of precipitates changes during growth and coarsening regimes, leading to modification of the macroscopic properties of the materials. Thus, understanding of this phenomenon is key to tailoring the precipitate strengthening of industrial alloys. In this article, a general approach to explain the shape instability of iron-rich nanoparticles in Cu-Fe-Co alloys during casting and ageing processes is proposed. The evolution of particle shape from sphere to cuboid to petal and finally splitting into eight subnanoparticles is observed using transmission electron microscopy. Phase-field modelling and thermodynamic calculations are combined into a general model that describes and elucidates the morphological evolution of precipitates in alloys in terms of particle size, interfacial and elastic strain energy, and chemical driving force. These findings have the potential to promote new microstructural design approaches for a wide range of materials.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Copper alloys, Precipitation, Morphological stability, Transmission electron microscopy, Phase field modelling
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-239959 (URN)10.1016/j.actamat.2018.10.013 (DOI)000451103800005 ()2-s2.0-85054834241 (Scopus ID)
Note

QC 20181211

Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
Petrik, M. V., Gornostyrev, Y. N. & Korzhavyi, P. . (2019). Point defect interactions with Guinier-Preston zones in Al-Cu based alloys: Vacancy mediated GPZ to θ′-phase transformation. Scripta Materialia, 165, 123-127
Open this publication in new window or tab >>Point defect interactions with Guinier-Preston zones in Al-Cu based alloys: Vacancy mediated GPZ to θ′-phase transformation
2019 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 165, p. 123-127Article in journal (Refereed) Published
Abstract [en]

The energetics of point defect interactions with a Guinier-Preston zone (GPZ) in Al alloys are systematically studied using ab initio calculations and a supercell approach. We find that vacancies can be trapped by GPZs and that the presence of a vacancy in a Cu layer qualitatively changes the solute–GPZ interactions. A vacancy mediated mechanism of GPZ to θ′-phase transformation is suggested and shown to be thermodynamically feasible, which involves the formation of structural vacancies and splitting of a GPZ layer into two half-vacant Cu layers. This mechanism, in combination with the calculated attractive solute-vacancy interactions, is predicted to result in the solute segregation at the interface between Al matrix and the forming θ′-phase precipitate.

Place, publisher, year, edition, pages
Acta Materialia Inc, 2019
Keywords
Ab initio calculations, Aluminum alloys, Phase transformation, Point defects
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-246433 (URN)10.1016/j.scriptamat.2019.02.024 (DOI)000463127300026 ()2-s2.0-85061991263 (Scopus ID)
Note

QC 20190329

Available from: 2019-03-29 Created: 2019-03-29 Last updated: 2019-04-29Bibliographically approved
Ghadami Yazdi, M., Lousada, C. M., Evertsson, J., Rullik, L., Soldemo, M., Bertram, F., . . . Göthelid, M. (2019). Structure dependent effect of silicon on the oxidation of Al(111) and Al(100). Surface Science, 684, 1-11
Open this publication in new window or tab >>Structure dependent effect of silicon on the oxidation of Al(111) and Al(100)
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2019 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 684, p. 1-11Article in journal (Refereed) Published
Abstract [en]

The effect of sub-monolayer silicon on the oxidation of Al(111) and Al(100) surfaces was investigated using X-ray Photoelectron Spectroscopy (XPS) and density functional theory (DFT) calculations. On both surfaces the adatom site is preferred over substituting Si into the Al-lattice; on Al(100) the four fold hollow site is vastly favored whereas on Al(111) bridge and hollow sites are almost equal in energy. Upon O 2 exposure, Si is not oxidized but buried at the metal/oxide interface under the growing aluminum oxide. On Al(111), Si has a catalytic effect on both the initial oxidation by aiding in creating a higher local oxygen coverage in the early stages of oxidation and, in particular, at higher oxide coverages by facilitating lifting Al from the metal into the oxide. The final oxide, as measured from the Al2p intensity, is 25–30% thicker with Si than without. This observation is valid for both 0.1 monolayer (ML) and 0.3 ML Si coverage. On Al(100), on the other hand, at 0.16 ML Si coverage, the initial oxidation is faster than for the bare surface due to Si island edges being active in the oxide growth. At 0.5 ML Si coverage the oxidation is slower, as the islands coalesce and he amount of edges reduces. Upon oxide formation the effect of Si vanishes as it is overgrown by Al 2 O 3 , and the oxide thickness is only 6% higher than on bare Al(100), for both Si coverages studied. Our findings indicate that, in addition to a vanishing oxygen adsorption energy and Mott potential, a detailed picture of atom exchange and transport at the metal/oxide interface has to be taken into account to explain the limiting oxide thickness.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Aluminum, Density functional theory, Oxidation, Silicon, X-ray photoelectron spectroscopy
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-246413 (URN)10.1016/j.susc.2019.02.005 (DOI)000470192900001 ()2-s2.0-85061563000 (Scopus ID)
Note

QC 20190402

Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-06-25Bibliographically approved
Delandar, A. H., Gorbatov, O. I., Selleby, M., Gornostyrev, Y. N. N. & Korzhavyi, P. . (2018). Ab-initio based search for late blooming phase compositions in iron alloys. Journal of Nuclear Materials, 509, 225-236
Open this publication in new window or tab >>Ab-initio based search for late blooming phase compositions in iron alloys
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2018 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 509, p. 225-236Article in journal (Refereed) Published
Abstract [en]

We present a systematic analysis, based on ab initio calculations, of concentrated solute arrangements and precipitate phases in Fe-based alloys. The input data for our analysis are the calculated formation and interaction energies of point defects in the iron matrix, as well as the energies of ordered compounds that represent end-members in the 4-sublattice compound energy model of a multicomponent solid solution of Mg, Al, Si, P, S, Mn, Ni, and Cu elements and also vacancies in bcc Fe. The list of compounds also includes crystal structures obtained by geometric relaxation of the end-member compounds that in the cubic structure show weak mechanical instabilities (negative elastic constants) and also the G-phase Mn-6(Ni,Fe)(16)(Si,P)(7) having a complex cubic structure. A database of calculated thermodynamic properties (crystal structure, molar volume, enthalpy of formation, and elastic constants) of the most stable late-blooming-phase candidates is thus obtained. The results of this ab initio based theoretical analysis compare well with the recent experimental observations and predictions of thermodynamic calculations employing Calphad methodology.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Iron alloys, ab initio calculations, Solute clusters, Precipitate phases
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:kth:diva-234563 (URN)10.1016/j.jnucmat.2018.06.028 (DOI)000442483300026 ()2-s2.0-85049458637 (Scopus ID)
Funder
Swedish Nuclear Fuel and Waste Management Company, SKBVinnova
Note

QC 20180919

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2019-08-20Bibliographically approved
Lousada, C. M., Johansson, A. J. & Korzhavyi, P. . (2018). Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) - Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer. ChemPhysChem, 19(17), 2159-2168
Open this publication in new window or tab >>Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) - Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer
2018 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 19, no 17, p. 2159-2168Article in journal (Refereed) Published
Abstract [en]

Understanding the surface site preference for single adsorbates, the interactions between adsorbates, how these interactions affect surface site specificity in adsorption and perturb the electronic states of surfaces is important for rationalizing the structure of interfaces and the growth of surface products. Herein, using density functional theory (DFT) calculations, we investigated the adsorption of H2S, HS and, S onto Cu(110). The surface site specificity observed for single adsorbates can be largely affected by the presence of other adsorbates, especially S that can affect the adsorption of other species even at distances of 13 Å. The large supercell employed with a surface periodicity of (6×6) allowed us to safely use the Helmholtz method for the determination of the dipole of the surface-adsorbate complex at low adsorbate coverages. We found that the surface perturbation induced by S can be explained by the charge transfer model, H2S leads to a perturbation of the surface that arises mostly from Pauli exclusion effects, whereas HS shows a mix of charge transfer and Pauli exclusion effects. These effects have a large contribution to the long range adsorbate-adsorbate interactions observed. Further support for the long range adsorbate-adsorbate interactions are the values of the adsorption energies of adsorbate pairs that are larger than the sum of the adsorption energies of the single adsorbates that constitute the pair. This happens even for large distances and thus goes beyond the H-bond contribution for the H-bond capable adsorbate pairs. Exploiting this knowledge we investigated two models for describing the first stages of growth of a layer of S-atoms at the surface: the formation of islands versus the formation of more homogeneous surface distributions of S-atoms. We found that for coverages lower than 0.5 ML the S-atoms prefer to cluster as islands that evolve to stripes along the [1 (Formula presented.) 0] direction with increasing coverage. At 0.5 ML a homogeneous distribution of S-atoms becomes more stable than the formation of stripes. For the coverage equivalent to 1 ML, the formation of two half-monolayers of S-atoms that disrupt the Cu−Cu bonds between the first and second layer is more favorable than the formation of 1 ML homogeneous coverage of S-atoms. Here the S−Cu bond distances and geometries are reminiscent of pyrite, covellite, and to some extent chalcocite. The small energy difference of ≈0.1 eV that exists between this structure and the formation of 1 ML suggests that in a real system at finite temperature both structures may coexist leading to a structure with even lower symmetry.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2018
Keywords
adsorbate-adsorbate interactions, copper sulfide growth, hydrogen sulfide, polarizability, sulfur adsorption
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-236702 (URN)10.1002/cphc.201800246 (DOI)000443680500008 ()2-s2.0-85052734894 (Scopus ID)
Funder
Swedish Nuclear Fuel and Waste Management Company, SKB
Note

Export Date: 22 October 2018; Article; CODEN: CPCHF; Correspondence Address: Lousada, C.M.; Department of Materials Science and Engineering, KTH Royal Institute of Technology SE-Sweden; email: cmlp@kth.se; Funding details: SKB, Svensk Kärnbränslehantering; Funding details: KTH, Kungliga Tekniska Högskolan; Funding text: Financial support from the Swedish Nuclear Fuel and Waste Management Company (SKB) is gratefully acknowledged. The computations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC): at the Center for High Performance Computing at the KTH – Royal Institute of Technology (PDC). QC 20181112

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Walbrühl, M., Blomqvist, A. & Korzhavyi, P. . (2018). Atomic diffusion in liquid nickel: First-principles modeling. Journal of Chemical Physics, 148(24), Article ID 244503.
Open this publication in new window or tab >>Atomic diffusion in liquid nickel: First-principles modeling
2018 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 148, no 24, article id 244503Article in journal (Refereed) Published
Abstract [en]

Self- and impurity diffusion coefficients are assessed in the liquid nickel system by the fundamental ab initio molecular dynamics approach. The impurity diffusion coefficients in the Ni-X systems (X=C, Co, N, Nb, Ta, Ti, W) are mostly not available in the current literature. The simulations are performed at four temperatures, in the range from 1903 to 2303 K, which allows to extract activation energies and frequency factors for the temperature dependent diffusion coefficient assuming an Arrhenius-type behavior in the liquid. In addition to the temperature dependence, the concentration-dependent impurity diffusion was investigated for the Ni-Co system. The data are of relevance for the development of the state-of-the art Ni-based superalloys and alternative binder systems in cemented carbides. The obtained theoretical results are in very good agreement with the limited experimental data for the diffusion in liquid Ni systems.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:kth:diva-232410 (URN)10.1063/1.5026348 (DOI)000437190300069 ()29960348 (PubMedID)2-s2.0-85049023346 (Scopus ID)
Note

QC 20180726

Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-07-26Bibliographically approved
Delandar, A. H., Gorbatov, O. I., Selleby, M., Gornostyrev, Y. N. & Korzhavyi, P. . (2018). End-member compounds of a 4-sublattice model of multicomponent BCC solid solutions. Data in Brief, 20, 1018-1022
Open this publication in new window or tab >>End-member compounds of a 4-sublattice model of multicomponent BCC solid solutions
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2018 (English)In: Data in Brief, E-ISSN 2352-3409, Vol. 20, p. 1018-1022Article in journal (Refereed) Published
Abstract [en]

The article presents ab initio calculated properties (total energies, lattice parameters, and elastic properties) for the complete set of 1540 end-member compounds within a 4-sublattice model of Fe-based solid solutions. The compounds are symmetry-distinct cases of integral site occupancy for superstructure Y (space group #227, type LiMgPdSn) chosen to represent the ordered arrangements of solvent atoms (Fe), solute atoms (Fe, Mg, Al, Si, P, S, Mn, Ni, Cu), and vacancies (Va) on the sites of a body-centered cubic lattice. The model is employed in the research article “Ab-initio based search for late blooming phase compositions in iron alloys” (Hosseinzadeh et al., 2018) [1].

Place, publisher, year, edition, pages
Elsevier Inc., 2018
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-236663 (URN)10.1016/j.dib.2018.08.086 (DOI)000450242200152 ()2-s2.0-85053047195 (Scopus ID)
Note

Export Date: 22 October 2018; Article; Correspondence Address: Korzhavyi, P.A.; Department of Materials Science and Engineering, KTH Royal Institute of TechnologySweden; email: pavelk@kth.se; Funding details: VINNOVA; Funding details: SKB, Svensk Kärnbränslehantering; Funding details: NSC; Funding details: 14, Minobrnauka, Ministry of Education and Science of the Russian Federation; Funding details: Z50.31.0043, Minobrnauka, Ministry of Education and Science of the Russian Federation; Funding details: Y26.31.0005, Minobrnauka, Ministry of Education and Science of the Russian Federation; Funding details: KTH, Kungliga Tekniska Högskolan; Funding details: K2–2017-080; Funding details: 211; Funding text: This work has been supported by Svensk Kärnbränslehantering AB, the Swedish Nuclear Fuel and Waste Management Company (SKB). The study has been carried out at the VINNEX center Hero-m financed by the Swedish Governmental Agency for Innovation Systems (VINNOVA), Swedish Industry , and the KTH Royal Institute of Technology . The computations were partly done on resources provided by the Swedish National Infrastructure for Computing (SNIC) at the National Supercomputer Center (NSC) in Linköping and at the Center for High Performance Computing (PDC) in Stockholm, Sweden. Ab initio calculations were carried out with support provided by the Ministry of Education and Science of the Russian Federation , Grants no. 14.Y26.31.0005 and 14.Z50.31.0043 . Analysis of theoretical data was supported by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST “MISIS” (No. K2–2017-080) implemented by a governmental decree dated 16 March 2013, No 211. Transparency document. QC 2018113

Available from: 2018-11-13 Created: 2018-11-13 Last updated: 2018-12-07Bibliographically approved
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