Monte Carlo study of thermodynamic properties and clustering in the bcc Fe-Cr system

Lavrentiev, M. Yu.; Drautz, Ralf; Nguyen-Manh, D.; Klaver, T.P.C.; Dudarev, S. L.

doi:10.1103/physrevb.75.014208

Cited by 127 publications

(85 citation statements)

References 43 publications

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“…Kinetic Monte Carlo (KMC) simulations performed by Bonny et al [24,25] showed that most of the Cr-rich precipitates (containing more than 95 at.% Cr) initially have sphere-like shapes in the Fe-(11.8-18)Cr matrix. In contrast to that, the Monte Carlo simulations based on the cluster expansion approximation done by Lavrentiev and co-workers [18] and Lavrentiev et al [26] predicted a clear polyhedral shape for the pure Cr cluster in the a phase containing about 10 at.% Cr and at 0 K. All above compositions for the interfaces are located in the bottom-left corner (x, y90:2) of Fig. 2 (i.e., for those alloys we have g 001 =g 110 91:2) and, therefore, the present study confirms the KMC results by Bonny et al [24,25]).…”

Section: According Tomentioning

confidence: 99%

“…In particular, the calculated anomalous negative mixing enthalpy at low Cr concentration, the threshold behavior of the surface concentration profile, or the peculiar alloying effects on the cubic elastic constants were all shown to be attributed to magnetism and to the particular Fermisurface topology [4,[13][14][15][16][17][18][19][20][21][22][23]. In order to obtain important information about the Cr-rich precipitates in Fe-Cr alloys, such as structure, mean size, number density, composition, and shape, several Monte Carlo simulations have been performed [18,[24][25][26]. For the Fe-Cr alloy with different compositions, after annealing for a period of time, the Cr or Cr-rich precipitates were found to have different shapes, either polyhedron or sphere-like.…”

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confidence: 98%

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

Johansson

et al. 2011

Physica Status Solidi (b)

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Using a first-principles quantum mechanical method, we calculated the (001) and (110) interfacial energies between the low temperature a and a 0 phases of Fe-Cr alloys as functions of chemical composition. We show that the interfacial energies and the interfacial energy anisotropy are highly composition dependent. In particular, the increasing interfacial energy anisotropy with decreasing compositional gap may induce different morphology of the decomposed phases for different compositions of the host alloys.

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Section: According Tomentioning

confidence: 99%

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confidence: 98%

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

Johansson

et al. 2011

Physica Status Solidi (b)

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“…LaSalle and Schwartz [18] investigated two different solution treatment temperatures of 850 and 1200°C and also found that the lower temperature gave faster decomposition upon subsequent aging. Furthermore, it has been found, both theoretically and experimentally, that there is a positive atomic short range order (SRO), i.e., clustering, above the miscibility gap in concentrated Fe-Cr alloys above about 10 at.% Cr [19][20][21][22][23]. Recently, Zhou et al [24] have reported atom probe tomography (APT) observations of the clustering of Cr in the bcc phase of ferritic and duplex stainless steels after solution treatment.…”

Section: Introductionmentioning

confidence: 99%

Effect of solution treatment on spinodal decomposition during aging of an Fe-46.5 at.% Cr alloy

et al. 2016

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Spinodal decomposition is a key phase transition in advanced materials and a significant effort is paid to the quantitative modeling of the phenomenon. The initial materials condition is often assumed to be random during modeling, but this may be an oversimplification. In this work, the effect of solution treatment above the miscibility gap, on spinodal decomposition during subsequent aging, has been investigated for an Fe-46.5 at.% Cr alloy. By atom probe tomography (APT), it is found that different extents of quenched-in Cr clustering exist after solution treatments at different temperatures. The clustering is pronounced at 800°C but decreases significantly with increasing temperature to 900°C. Thermodynamic Monte Carlo simulations show that there is a difference in atomic short range order between the different solution treatment temperatures. By APT, it is, furthermore, found that the kinetics of spinodal decomposition at 500°C, i.e., within the miscibility gap, is enhanced in the initial alloy condition, where Cr was less randomly distributed. These observations are supported by kinetic Monte Carlo simulations, predicting a similar but less pronounced qualitative effect on spinodal decomposition kinetics. Other possible reasons for the enhanced kinetics could be related to clustering of interstitial elements and/ or sigma phase, but neither was found in the experiments. Nonetheless, the observations in this work suggest that it is necessary to implement a modeling strategy, where the initial structure is properly accounted for when simulating spinodal decomposition.

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“…In rigid lattice MC simulations [12,20,[34][35][36][37] using Ising-type interaction the Hamiltonian must be made temperature dependent. Semiempirical potentials have been used in both Metropolis MC (MMC) [38][39][40] and kinetic MC (KMC) [9,[41][42][43][44][45][46][47] studies.…”

Section: B Large-scale Monte Carlo Simulationsmentioning

confidence: 99%

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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Monte Carlo study of thermodynamic properties and clustering in the bcc Fe-Cr system

Cited by 127 publications

References 43 publications

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

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

Effect of solution treatment on spinodal decomposition during aging of an Fe-46.5 at.% Cr alloy

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

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