Composition and orientation dependence of the interfacial energy in Fe–Cr stainless steel alloys

Lu, Song; Hu, Qing‐Miao; Johansson, Börje; Vitos, Levente

doi:10.1002/pssb.201147123

Cited by 8 publications

(4 citation statements)

References 47 publications

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“…% chromium the layer structure changes into a single precipitate again with (110) facets. The appearance of (110) facets is in line with ab initio interface calculations [61] which show that the (110) interface has the lowest energy which compares well with the surface energies in Fig. 2.…”

Section: Monte Carlo Simulationssupporting

confidence: 85%

Segregation, precipitation, andα−α′phase separation in Fe-Cr alloys

et al. 2015

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Iron-chromium alloys, the base components of various stainless steel grades, have numerous technologically and scientifically interesting properties. However, these features are not yet sufficiently understood to allow their full exploitation in technological applications. In this work, we investigate segregation, precipitation, and phase separation in Fe-Cr systems analyzing the physical mechanisms behind the observed phenomena. To get a comprehensive picture of Fe-Cr alloys as a function of composition, temperature, and time the present investigation combines Monte Carlo simulations using semiempirical interatomic potential, first-principles total energy calculations, and experimental spectroscopy. In order to obtain a general picture of the relation of the atomic interactions and properties of Fe-Cr alloys in bulk, surface, and interface regions several complementary methods have to be used. Using the exact muffin-tin orbitals method with the coherent potential approximation (CPA-EMTO) the effective chemical potential as a function of Cr content (0-15 at. % Cr) is calculated for a surface, second atomic layer, and bulk. At ∼10 at. % Cr in the alloy the reversal of the driving force of a Cr atom to occupy either bulk or surface sites is obtained. The Cr-containing surfaces are expected when the Cr content exceeds ∼10 at. %. The second atomic layer forms about a 0.3 eV barrier for the migration of Cr atoms between the bulk and surface atomic layer. To get information on Fe-Cr in larger scales we use semiempirical methods. However, for Cr concentration regions less than 10 at. %, the ab initio (CPA-EMTO) result of the important role of the second atomic layer to the surface is not reproducible from the large-scale Monte Carlo molecular dynamics (MCMD) simulation. On the other hand, for the nominal concentration of Cr larger than 10 at. % the MCMD simulations show the precipitation of Cr into isolated pockets in bulk Fe-Cr and the existence of the upper limit of the solubility of Cr into Fe layers in Fe/Cr layer systems. For high Cr concentration alloys the performed spectroscopic measurements support the MCMD simulations. Hard x-ray photoelectron spectroscopy and Auger electron spectroscopy investigations were carried out to explore Cr segregation and precipitation in the Fe/Cr double layer and Fe 0.95 Cr 0.05 and Fe 0.85 Cr 0.15 alloys. Initial oxidation of Fe-Cr was investigated experimentally at 10 −8 Torr pressure of the spectrometers showing intense Cr 2 O 3 signal. Cr segregation and the formation of Cr-rich precipitates were traced by analyzing the experimental atomic concentrations and chemical shifts with respect to annealing time, Cr content, and kinetic energy of the exited electron.

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Section: Monte Carlo Simulationssupporting

confidence: 85%

Segregation, precipitation, andα−α′phase separation in Fe-Cr alloys

et al. 2015

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“…A group of researchers investigated Fe-Cr [90][91][92][93][94][95][96][97][98], Fe-Co [99,100], Fe-C [101,102] and Fe-Mn based alloys [103][104][105] by means of atom probe tomography, neutron diffraction, Mossbauer spectrometry, magnetic measurements, X-ray diffraction, transmission and scanning electron microscopy, electron diffraction, resistivity measurements and other techniques such as hardness and compression tests.…”

Section: Spinodal Decomposition In Fe-based Alloysmentioning

confidence: 99%

Improvements in spinodal alloys from past to present

Fındık

2012

Materials & Design

115

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“…The static properties of the iron-chromium system have been extensively studied at the atomic level. For example, surface [7] and interface [8] energies and surface segregation energies of chromium [9] have been calculated for Fe-Cr alloys using ab initio methods. Importantly, such calculations have shown that the aforementioned critical Cr concentration for the onset of the corrosion resistance in stainless steels closely coincides with an onset of anomalous surface segregation of Cr in Fe-Cr alloys [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Their disagreement with ab initio calculations is succinctly demonstrated by inspecting the segregation of a Cr atom from the bulk to the surface of a bcc Fe crystal: all three semi-empirical models predict the Cr atom to segregate to the second layer of Fe atoms, whereas according to ab initio calculations the first layer (i.e., the surface itself) should be preferred [24]. In addition, all three models fail to reproduce the ab initio results of Fe-Cr interface energies [8]. As a consequence of these shortcomings, no Monte Carlo simulations of atom kinetics near Fe-Cr surfaces have been performed, and the current atomic-level knowledge of surface physics in Fe-Cr alloys is far from satisfactory, despite the practical importance of the topic in relation to the corrosion of steel surfaces.…”

Section: Introductionmentioning

confidence: 99%

Interatomic Fe-Cr potential for modeling kinetics on Fe surfaces

Kuopanportti¹,

Ropo²,

Holmberg³

et al. 2021

Preprint

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To enable accurate molecular dynamics simulations of iron-chromium alloys with surfaces, we develop, based on density-functional-theory (DFT) calculations, a new interatomic Fe-Cr potential in the Tersoff formalism. Contrary to previous potential models, which have been designed for bulk Fe-Cr, we extend our potential fitting database to include not only conventional bulk properties but also surface-segregation energies of Cr in bcc Fe. In terms of reproducing our DFT results for the bulk properties, the new potential is found to be superior to the previously developed Tersoff potential and competitive with the concentration-dependent and two-band embedded-atom-method potentials. For Cr segregation toward the surface of an Fe-Cr alloy, only the new potential agrees with our DFT calculations in predicting preferential segregation of Cr to the topmost surface layer, instead of the second layer preferred by the other potentials. We expect this rectification to foster future research, e.g., on the mechanisms of corrosion resistance of stainless steels at the atomic level.

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Composition and orientation dependence of the interfacial energy in Fe–Cr stainless steel alloys

Cited by 8 publications

References 47 publications

Segregation, precipitation, andα−α′phase separation in Fe-Cr alloys

Segregation, precipitation, andα−α′phase separation in Fe-Cr alloys

Improvements in spinodal alloys from past to present

Interatomic Fe-Cr potential for modeling kinetics on Fe surfaces

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