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New Structural Insight into Interface-Controlled α–σ Phase Transformation in Fe-Cr Alloys. QUANTUM BEAM SCIENCE 2018. [DOI: 10.3390/qubs2040027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Synchrotron Laue microdiffraction scanning is used for the ex situ study of the body-centered, cubic-to-tetragonal phase transformation that occurs in equiatomic polycrystalline Fe-Cr alloys at temperatures between 550 and 800 °C. Grain orientation and grain strains were scanned with a micron step resolution after annealing at 700 °C for 12 h. Further microstructural details on the early stage of the transformation, and more particularly on the cubic-to-tetragonal phase interface, were achieved. Only the α and ordered σ phases were detected. The crystallographic relationships at the interface between the two phases did not follow the predicted rules; this result is discussed in relation to the measured microstrains.
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Souissi M, Sluiter MHF, Matsunaga T, Tabuchi M, Mills MJ, Sahara R. Effect of mixed partial occupation of metal sites on the phase stability of γ-Cr 23-xFe x C 6 (x = 0-3) carbides. Sci Rep 2018; 8:7279. [PMID: 29740098 PMCID: PMC5940797 DOI: 10.1038/s41598-018-25642-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 04/25/2018] [Indexed: 11/22/2022] Open
Abstract
The effect of mixed partial occupation of metal sites on the phase stability of the γ-Cr23−xFexC6 (x = 0–3) carbides is explored as function of composition and temperature. Ab initio calculations combined with statistical thermodynamics approaches reveal that the site occupation of the carbides may be incorrectly predicted when only the commonly used approach of full sublattice occupation is considered. We found that the γ-M23C6 structure can be understood as a familiar sodium chloride structure with positively charged rhombic dodecahedron (M(4a) M12(48h)) and negatively charged cubo-octahedron (M8(32f) C6(24e)) super-ion clusters, together with interstitial metal atoms at the 8c sites. The stability of the partially occupied phase can be easily rationalized on the basis of a super-ion analysis of the carbide phase. This new understanding of γ-M23C6 carbides may facilitate further development of high-chromium heat-resistant steels.
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Affiliation(s)
- Maaouia Souissi
- Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
| | - Marcel H F Sluiter
- Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands
| | - Tetsuya Matsunaga
- Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.,Department of Materials Science and Engineering, The Ohio State University, 478 Watts Hall, 2041 College Rd, Columbus, OH, 43210, USA
| | - Masaaki Tabuchi
- Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
| | - Michael J Mills
- Department of Materials Science and Engineering, The Ohio State University, 478 Watts Hall, 2041 College Rd, Columbus, OH, 43210, USA
| | - Ryoji Sahara
- Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
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Palumbo M, Fries SG, Pasturel A, Alfè D. Anharmonicity, mechanical instability, and thermodynamic properties of the Cr-Re σ-phase. J Chem Phys 2014; 140:144502. [PMID: 24735300 DOI: 10.1063/1.4869800] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using density-functional theory in combination with the direct force method and molecular dynamics we investigate the vibrational properties of a binary Cr-Re σ-phase. In the harmonic approximation, we have computed phonon dispersion curves and density of states, evidencing structural and chemical effects. We found that the σ-phase is mechanically unstable in some configurations, for example, when all crystallographic sites are occupied by Re atoms. By using a molecular-dynamics-based method, we have analysed the anharmonicity in the system and found negligible effects (~0.5 kJ/mol) on the Helmholtz energy of the binary Cr-Re σ-phase up to 2000 K (~0.8T(m)). Finally, we show that the vibrational contribution has significant consequences on the disordering of the σ-phase at high temperature.
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Affiliation(s)
- Mauro Palumbo
- ICAMS, Ruhr University Bochum, Universität Str. 150, D-44801 Bochum, Germany
| | - Suzana G Fries
- ICAMS, Ruhr University Bochum, Universität Str. 150, D-44801 Bochum, Germany
| | - Alain Pasturel
- SIMAP, UMR CNRS-INPG-UJF 5266, BP 75, F-38402 Saint Martin d'Hères, France
| | - Dario Alfè
- Department of Earth Sciences, Department of Physics and Astronomy, London Centre for Nanotechnology and Thomas Young Centre@UCL, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Crivello JC, Breidi A, Joubert JM. χ and σ Phases in Binary Rhenium–Transition Metal Systems: a Systematic First-Principles Investigation. Inorg Chem 2013; 52:3674-86. [DOI: 10.1021/ic302142w] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jean-Claude Crivello
- Chimie Métallurgique des Terres Rares, Institut de
Chimie et des Matériaux Paris-Est, CNRS, Université Paris-Est, UMR 7182, 2−8 rue Henri Dunant, 94320
Thiais, France
| | - Abedalhasan Breidi
- Chimie Métallurgique des Terres Rares, Institut de
Chimie et des Matériaux Paris-Est, CNRS, Université Paris-Est, UMR 7182, 2−8 rue Henri Dunant, 94320
Thiais, France
| | - Jean-Marc Joubert
- Chimie Métallurgique des Terres Rares, Institut de
Chimie et des Matériaux Paris-Est, CNRS, Université Paris-Est, UMR 7182, 2−8 rue Henri Dunant, 94320
Thiais, France
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Non-Stoichiometry and Calphad Modeling of Frank-Kasper Phases. APPLIED SCIENCES-BASEL 2012. [DOI: 10.3390/app2030669] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Ab Initio Study of Lattice Site Occupancies in Binary Sigma Phases Using a Single-Site Mean Field Model. APPLIED SCIENCES-BASEL 2012. [DOI: 10.3390/app2030654] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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McEniry EJ, Madsen GKH, Drain JF, Drautz R. Tight-binding simulation of transition-metal alloys. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:276004. [PMID: 21690660 DOI: 10.1088/0953-8984/23/27/276004] [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
In order to perform atomistic simulations of steel, it is necessary to have a detailed understanding of the complex interatomic interactions in transition metals and their alloys. The tight-binding approximation provides a computationally efficient, yet accurate, method to investigate such interactions. In the present work, an orthogonal tight-binding model for Fe, Mn and Cr, with the explicit inclusion of magnetism, has been parameterized from ab initio density-functional calculations.
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Affiliation(s)
- Eunan J McEniry
- Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universität Bochum, Germany.
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Korzhavyi PA, Sundman B, Selleby M, Johansson B. Atomic, Electronic, and Magnetic Structure of Iron-Based Sigma-Phases. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-842-s4.10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTA combination of ab initio total energy calculations with Calphad approach is applied to model the site occupancy and thermodynamic properties of the Fe-Cr, Co-Cr, Fe-V, and Fe-Mo binary sigma-phases as a function of composition and temperature. For each binary sigma-phase the parameters of the model are the ab initio calculated total energies of so-called end-member compounds, which represent all the 25=32 variants of complete occupancy of each of the five crystallographically inequivalent sites by one or the other alloy component. The paramagnetic state of the sigma-phases has been taken into account within the disordered local moment approach. The Fe and Co atoms are found to retain high spin moments when they occupy high-coordination-number sites in the structure. Using our model we were able to reproduce the experimentally observed site occupancy in the FeCr sigma-phase. The calculated site occupancies in the Co-Cr, Fe-V, and Fe-Mo sigma-phases are also presented and discussed.
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Crivello JC, Joubert JM. First principles calculations of the σ and χ phases in the Mo-Re and W-Re systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:035402. [PMID: 21386285 DOI: 10.1088/0953-8984/22/3/035402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The total energies of all the ordered configurations of the σ and χ phases have been calculated by using first principles methodology in both Mo-Re and W-Re systems. These two complex structures possess 5 and 4 inequivalent sites generating 32 and 16 different ordered configurations, respectively, for a binary A-B system. The converged total energies of all the fully relaxed structures have been used to compute the occupancy of the inequivalent sites as a function of composition and temperature by using the Bragg-Williams approximation in the complete composition range. It is shown that the configurational entropy stabilizes the σ and χ phases in the Mo-Re and W-Re systems. The results evidence the preference of Re for lower coordination number site occupancy and are in very good agreement with the experimental measurements. Tentative ab initio phase diagrams have also been drawn.
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Affiliation(s)
- J-C Crivello
- ICMPE-CMTR, CNRS UMR-7182, 2-8, rue Henri Dunant, 94320 Thiais, France.
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Wille LT, Nonas B, Dederichs PH, Dreyssé H. Growth mode of Cr on Fe(001) described by ab-initio interactions. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/13642819808206772] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- L. T. Wille
- a Department of Physics , Florida Atlantic University , Boca Raton , Florida , 33431 , USA
| | - B. Nonas
- b Institute für Festkörperforschung, Forschungszentrum Jülich , D-52425 , Jülich , Germany
| | - P. H. Dederichs
- b Institute für Festkörperforschung, Forschungszentrum Jülich , D-52425 , Jülich , Germany
| | - H. Dreyssé
- c Institut de Physique et Chimie des Matériaux de Strasbourg , 23 rue du Loess, BP 20 CR, F-67037 , Strasbourg , France
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Kerkau A, Grüner D, Ormeci A, Prots Y, Borrmann H, Schnelle W, Bischoff E, Grin Y, Kreiner G. Site Occupation Reversal in the C14 Laves Phase Nb(Cr1-xCox)2. Z Anorg Allg Chem 2009. [DOI: 10.1002/zaac.200801411] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Cieslak J, Tobola J, Dubiel SM, Kaprzyk S, Steiner W, Reissner M. Electronic structure of a σ-FeCr compound. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:235234. [PMID: 21694325 DOI: 10.1088/0953-8984/20/23/235234] [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
The electronic structure of a σ-FeCr compound in a paramagnetic state was calculated for the first time in terms of isomer shifts and quadrupole splittings. The former were calculated using the charge self-consistent Korringa-Kohn-Rostoker (KKR) Green's function technique, while the latter were estimated from an extended point charge model. The calculated quantities combined with recently measured site occupancies were successfully used to analyze a Mössbauer spectrum recorded at room temperature using only five fitting parameters namely background, total intensity, linewidth, IS0 (necessary to adjust the refined spectrum to the used Mössbauer source) and the QS proportionality factor. Theoretically determined changes of the isomer shift for the σ-FeCr sample were found to be in line with the corresponding ones measured on a α-FeCr sample.
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Affiliation(s)
- J Cieslak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland
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