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A combined experimental and first-principle study on the oxidation mechanism of super austenitic stainless steel S32654 at 900 °C. Sci Rep 2017; 7:871. [PMID: 28408753 PMCID: PMC5429827 DOI: 10.1038/s41598-017-00903-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/16/2017] [Indexed: 11/08/2022] Open
Abstract
A combined experimental and first-principle study on the oxidation mechanism of super austenitic stainless steel S32654 at 900 °C for a short time period (1, 3, and 5 h) in air is presented. The samples exhibit excellent oxidation resistance because of the initial and gradual formation of the denser Fe- and Cr-rich layer with increasing oxidation time. Meanwhile, the Mo-rich layer gradually forms because of the Mo diffusion, which results in the formation of the oxide layer with two distinct regions: an inner Fe- and Cr-rich layer and an outer Mo-rich layer. Density functional theory is applied to investigate the diffusion behaviour of Mo atom in the Fe-Cr-Ni/Cr2O3 interface and the effects of alloying elements (Fe, Ni, and Mn) on the Mo diffusion. The Mo originating from the alloy matrix tends to diffuse into the Cr2O3 part, thereby resulting in the formation of the continuous Mo-rich layer, which is consistent with the experimental behaviour. Moreover, the introduction of Ni to the Cr2O3 part can promote the Mo diffusion and the formation of the Mo-rich oxide layer, whereas Fe and Mn can hinder the Mo diffusion. The calculated results provide a microcosmic explanation of the experimental results.
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Agarwal R, Trinkle DR. Exact Model of Vacancy-Mediated Solute Transport in Magnesium. PHYSICAL REVIEW LETTERS 2017; 118:105901. [PMID: 28339274 DOI: 10.1103/physrevlett.118.105901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Indexed: 06/06/2023]
Abstract
Most substitutional solutes in solids diffuse via vacancies. However, widely used analytic models for diffusivity make uncontrolled approximations in the relations between atomic jump rates that reduce accuracy. Symmetry analysis of the hexagonal close packed crystal identifies more distinct vacancy transitions than prior models, and a Green function approach computes diffusivity exactly for solutes in magnesium. We find large differences for the solute drag of Al, Zn, and rare earth solutes, and improved diffusion activation energies-highlighting the need for exact analytic transport models.
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Affiliation(s)
- Ravi Agarwal
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Dallas R Trinkle
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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Keast VJ, Wallace JW, Wrightson CJ, Tai M, Gentle A, Arnold MD, Cortie MB. The effect of vacancies on the optical properties of AuAl₂. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:505501. [PMID: 26610233 DOI: 10.1088/0953-8984/27/50/505501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
AuAl2 is an intermetallic compound with a vivid purple colour attributable to a bulk plasmon energy in the visible part of the spectrum. However, the colour of as-deposited thin films is not as strong and only develops upon annealing. Density functional theory calculations of the dielectric function are presented for a variety of vacancy types and concentrations. The results support the view that the effect of annealing on colour is correlated with a reduction in concentration of Al vacancies. The effect of vacancies on the optical properties can be understood as arising from the complex interplay between interband transitions around the Fermi level and the plasmon energy.
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Affiliation(s)
- V J Keast
- School of Mathematical and Physical Sciences, University of Newcastle, Callaghan NSW 2308, Australia
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Delczeg L, Delczeg-Czirjak EK, Johansson B, Vitos L. Density functional study of vacancies and surfaces in metals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:045006. [PMID: 21406880 DOI: 10.1088/0953-8984/23/4/045006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We compare the performances of three common gradient-level exchange-correlation functionals for metallic bulk, surface and vacancy systems. We find that approximations which, by construction, give similar results for the jellium surface, show large deviations for realistic systems. The particular charge density and density gradient dependence of the exchange-correlation energy densities are shown to be the reason behind the obtained differences. Our findings confirm that both the global (total energy) and the local (energy density) behavior of the exchange-correlation functional should be monitored for a consistent functional design.
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Affiliation(s)
- L Delczeg
- Applied Materials Physics, Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
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Vinko SM, Zastrau U, Mazevet S, Andreasson J, Bajt S, Burian T, Chalupsky J, Chapman HN, Cihelka J, Doria D, Döppner T, Düsterer S, Dzelzainis T, Fäustlin RR, Fortmann C, Förster E, Galtier E, Glenzer SH, Göde S, Gregori G, Hajdu J, Hajkova V, Heimann PA, Irsig R, Juha L, Jurek M, Krzywinski J, Laarmann T, Lee HJ, Lee RW, Li B, Meiwes-Broer KH, Mithen JP, Nagler B, Nelson AJ, Przystawik A, Redmer R, Riley D, Rosmej F, Sobierajski R, Tavella F, Thiele R, Tiggesbäumker J, Toleikis S, Tschentscher T, Vysin L, Whitcher TJ, White S, Wark JS. Electronic structure of an XUV photogenerated solid-density aluminum plasma. PHYSICAL REVIEW LETTERS 2010; 104:225001. [PMID: 20867176 DOI: 10.1103/physrevlett.104.225001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Indexed: 05/29/2023]
Abstract
By use of high intensity XUV radiation from the FLASH free-electron laser at DESY, we have created highly excited exotic states of matter in solid-density aluminum samples. The XUV intensity is sufficiently high to excite an inner-shell electron from a large fraction of the atoms in the focal region. We show that soft-x-ray emission spectroscopy measurements reveal the electronic temperature and density of this highly excited system immediately after the excitation pulse, with detailed calculations of the electronic structure, based on finite-temperature density functional theory, in good agreement with the experimental results.
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Affiliation(s)
- S M Vinko
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom.
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Wang K, Reeber RR. The perfect crystal, thermal vacancies and the thermal expansion coefficient of aluminium. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/01418610008212140] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Abstract
Electronic structure calculations at macroscopic scales are employed to investigate the crucial role of a defect core in the energetics of vacancies in aluminium. We find that vacancy core energy is significantly influenced by the state of deformation at the vacancy core, especially volumetric strains. Insights from the core electronic structure and computed displacement fields show that this dependence on volumetric strains is closely related to the changing nature of the core structure under volumetric deformations. These results are in sharp contrast to mechanics descriptions based on elastic interactions that often consider defect core energies as an inconsequential constant. Calculations suggest that the variation in core energies with changing macroscopic deformations is quantitatively more significant than the corresponding variation in relaxation energies associated with elastic fields. Upon studying the influence of various macroscopic deformations, which include volumetric, uniaxial, biaxial and shear deformations, on the formation energies of vacancies, we show that volumetric deformations play a dominant role in governing the energetics of these defects. Further, by plotting formation energies of vacancies and di-vacancies against the volumetric strain corresponding to any macroscopic deformation, we find that all variations in the formation energies collapse on to a universal curve. This suggests a universal role of volumetric strains in the energetics of vacancies. Implications of these results in the context of dynamic failure in metals through shock-induced spalling are analysed.
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Affiliation(s)
- Vikram Gavini
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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Gavini V. Role of macroscopic deformations in energetics of vacancies in aluminum. PHYSICAL REVIEW LETTERS 2008; 101:205503. [PMID: 19113353 DOI: 10.1103/physrevlett.101.205503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Indexed: 05/27/2023]
Abstract
Electronic structure calculations on million-atom samples are employed to investigate the effect of macroscopic deformations on energetics of vacancies in aluminum. We find that volumetric strain associated with a deformation largely governs the formation energies of monovacancies and divacancies. The calculations suggest that nucleation of these defects is increasingly favorable under volumetric expansion, so much to the point that they become thermodynamically favorable under large positive volumetric strains. On the contrary, on an average, existing vacancies are found to bind preferentially under compressive volumetric strains. Shear deformations did not affect the formation energies of vacancies, but strongly influenced the 110 divacancy binding energies, causing them to orient under energetically preferential directions.
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Affiliation(s)
- Vikram Gavini
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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Carneiro JWDM, Cruz MTDM. Density Functional Theory Study of the Adsorption of Formaldehyde on Pd4 and on Pd4/γ-Al2O3 Clusters. J Phys Chem A 2008; 112:8929-37. [DOI: 10.1021/jp801591z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- José Walkimar de M. Carneiro
- Departamento de Química Inorgânica, and Pós-Graduação em Química Orgânica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, 24020-141 Niterói - RJ, Brazil
| | - Maurício T. de M. Cruz
- Departamento de Química Inorgânica, and Pós-Graduação em Química Orgânica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, 24020-141 Niterói - RJ, Brazil
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Huang C, Carter EA. Transferable local pseudopotentials for magnesium, aluminum and silicon. Phys Chem Chem Phys 2008; 10:7109-20. [DOI: 10.1039/b810407g] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Perron A, Politano O, Vignal V. Quenched molecular dynamics studies on the extraction energy of aluminum atoms. SURF INTERFACE ANAL 2008. [DOI: 10.1002/sia.2678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ho G, Ong MT, Caspersen KJ, Carter EA. Energetics and kinetics of vacancy diffusion and aggregation in shocked aluminium via orbital-free density functional theory. Phys Chem Chem Phys 2007; 9:4951-66. [PMID: 17851591 DOI: 10.1039/b705455f] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A possible mechanism for shock-induced failure in aluminium involves atomic vacancies diffusing through the crystal lattice and agglomerating to form voids, which continue to grow, ultimately resulting in ductile fracture. We employ orbital-free density functional theory, a linear-scaling first-principles quantum mechanics method, to study vacancy formation, diffusion, and aggregation in aluminium under shock loading conditions of compression and tension. We calculate vacancy formation and migration energies, and find that while nearest-neighbor vacancy pairs are unstable, next-nearest-neighbor vacancy pairs are stable. As the number of nearby vacancies increases, we predict that vacancy clusters preferentially grow through next-nearest-neighbor vacancies. The energetics are found to be greatly affected by expansion and compression, leading to insight as to how vacancies behave under shock conditions.
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Affiliation(s)
- Gregory Ho
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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Remediakis IN, Kaxiras E, Chen M, Friend CM. Dinitrosyl formation as an intermediate stage of the reduction of NO in the presence of MoO3. J Chem Phys 2003. [DOI: 10.1063/1.1556846] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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Finite difference methods for ab initio electronic structure and quantum transport calculations of nanostructures. HANDBOOK OF NUMERICAL ANALYSIS 2003. [DOI: 10.1016/s1570-8659(03)10009-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Korhonen T, Puska MJ, Nieminen RM. First-principles calculation of positron annihilation characteristics at metal vacancies. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:15016-15024. [PMID: 9985557 DOI: 10.1103/physrevb.54.15016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Hoshino T, Zeller R, Dederichs PH. Local-density-functional calculations for defect interactions in Al. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:8971-8974. [PMID: 9982398 DOI: 10.1103/physrevb.53.8971] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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