First-principles study of atomic ordering in fcc Ni-Cr alloys

Rahaman, Moshiour; Johansson, Börje; Ruban, Andrei V.

doi:10.1103/physrevb.89.064103

Cited by 29 publications

(27 citation statements)

References 57 publications

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“…The main reason for possible problems is the quite different d-band filling of Cr and Ni, which can substantially decrease the accuracy of the CPA due to substantial local environment effects. This was already reported for Ni-Cr binary alloys [24].…”

Section: B Electronic Structure Of Random Fcc Cr 25 Fe 25 Co 25 Ni 2supporting

confidence: 82%

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Local order in Cr-Fe-Co-Ni: Experiment and electronic structure calculations

et al. 2019

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A quenched-in state of thermal equilibrium (at 723 K) in a single crystal of Cr-Fe-Co-Ni close to equal atomic percent was studied. Atom probe tomography revealed a single-phase state with no signs of long-range order. The presence of short-range order (SRO) was established by diffuse x-ray scattering exploiting the variation in scattering contrast close to the absorption edges of the constituents: At the incoming photon energies of 5969, 7092, and 8313 eV, SRO maxima that result from the linear superposition of the six partial SRO scattering patterns, were always found at X position. Electronic structure calculations showed that this type of maximum stems from the strong Cr-Ni and Cr-Co pair correlations, that are furthermore connected with the largest scattering contrast at 5969 eV. The calculated effective pair interaction parameters revealed an order-disorder transition at approximately 500 K to a L1 2-type (Fe,Co,Ni) 3 Cr structure. The calculated magnetic exchange interactions were dominantly of the antiferromagnetic type between Cr and any other alloy component and ferromagnetic between Fe, Co, and Ni. They yielded a Curie temperature (T C) of 120 K, close to experimental findings. Despite the low value of T C , the global magnetic state strongly affects chemical and elastic interactions in this system. In particular, it significantly increases the ordering tendency in the ferromagnetic state compared to the paramagnetic one.

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Section: B Electronic Structure Of Random Fcc Cr 25 Fe 25 Co 25 Ni 2supporting

confidence: 82%

“…Interestingly and in contrast to the binary Ni-Cr system, a diffuse maximum in local order is no longer found at W position. This location was well established for Ni-11 (20,25,33) at.% Cr by diffuse x-ray and neutron scattering [20][21][22][23] and confirmed by a recent first-principles study [24].…”

Section: Introductionsupporting

confidence: 74%

Local order in Cr-Fe-Co-Ni: Experiment and electronic structure calculations

et al. 2019

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“…In contrast, many others believed that only short-range order occurs in the alloys with Cr concentration below ~25 at% [45,47]. Short-range order in this family of alloys has been measured repeatedly using diffuse neutron [48,49] and X-ray [50] scattering and theoretically studied by first-principles calculations [51].…”

Section: Specific Heatmentioning

confidence: 99%

Thermophysical properties of Ni-containing single-phase concentrated solid solution alloys

Jin

et al. 2017

Materials & Design

113

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Temperature dependent thermophysical properties, including specific heat capacity, lattice thermal expansion, thermal diffusivity and conductivity, have been systematically studied in Ni and eight Ni-containing single-phase face-centered-cubic concentrated solid solution alloys, at elevated temperatures up to 1273 K. The alloys have similar specific heat values of 0.4 -0.5Jg -1 K -1 at room temperature, but their temperature dependence varies greatly due to Curie and K-state transitions. The lattice, electronic, and magnetic contributions to the specific heat have been separated based on first-principles methods in NiCo, NiFe, Ni-20Cr and NiCoFeCr. The alloys have similar thermal expansion behavior, with the exception that NiFe and NiCoFe have much lower thermal expansion coefficient in their ferromagnetic state due to magnetostriction effects. Calculations based on the quasi-harmonic approximation accurately predict the temperature dependent lattice parameter of NiCo and NiFe with less than 0.2% error, but underestimated that of Ni-20Cr by 1%, compared to the values determined from neutron diffraction. All the alloys containing Cr have very similar thermal conductivity, which is much lower than that of Ni and the alloys without Cr, due to the large magnetic disorder.

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“…In SIM, energies of ordered structures are computed using DFT, and then ECIs are obtained through least-squares fitting. Both techniques have been successfully applied to binary alloy sub-systems of Fe-Cr-Ni [29][30][31][32][33][34][35][36] . However, ternary Fe-Cr-Ni alloys have not received attention.…”

Section: Introductionmentioning

confidence: 99%

Phase stability of ternary fcc and bcc Fe-Cr-Ni alloys

et al. 2015

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The phase stability of fcc and bcc magnetic binary Fe-Cr, Fe-Ni and Cr-Ni alloys, and ternary Fe-Cr-Ni alloys is investigated using a combination of Density Functional Theory (DFT), Cluster Expansion (CE) and Magnetic Cluster Expansion (MCE) approaches. Energies, magnetic moments, and volumes of more than 500 alloy structures have been evaluated using DFT, and the predicted most stable configurations are compared with experimental observations. Deviations from the Vegard law in fcc Fe-Cr-Ni alloys, resulting from the non-linear variation of atomic magnetic moments as functions of alloy composition, are observed. Accuracy of the CE model is assessed against the DFT data, where for ternary Fe-Cr-Ni alloys the cross-validation error is found to be less than 12 meV/atom. A set of cluster interaction parameters is defined for each alloy, where it is used for predicting new ordered alloy structures. Fcc Fe2CrNi phase with Cu2NiZn-like crystal structure is predicted to be the global ground state of ternary Fe-Cr-Ni alloys, with the lowest chemical ordering temperature of 650K. DFT-based Monte Carlo (MC) simulations are applied to the investigation of order-disorder transitions in Fe-Cr-Ni alloys. Enthalpies of formation of ternary alloys predicted by MC simulations at 1600K, combined with magnetic correction derived from MCE, are in excellent agreement with experimental values measured at 1565K. The relative stability of fcc and bcc phases is assessed by comparing the free energies of alloy formation. Evaluation of the free energies involved the application of a dedicated algorithm for computing configurational entropies of the alloys. Chemical order is analyzed, as a function of temperature and composition, in terms of the Warren-Cowley Short-Range Order (SRO) parameters and effective chemical pairwise interactions. In addition to compositions close to binary intermetallic phases CrNi2, FeNi, FeNi3 and FeNi8, pronounced chemical order is found in fcc alloys near the centre of the ternary alloy composition triangle. The calculated SRO parameters compare favourably with experimental data on binary and ternary alloys. Finite temperature magnetic properties of fcc Fe-Cr-Ni alloys are investigated using an MCE Hamiltonian parameterized using a DFT database of energies and magnetic moments computed for a large number of alloy configurations. MCE simulations show that the ordered ternary Fe2CrNi alloy phase remains magnetic up to 850-900 K due to strong anti-ferromagnetic coupling between (Fe,Ni) and Cr atoms in the ternary Fe-Cr-Ni matrix.

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First-principles study of atomic ordering in fcc Ni-Cr alloys

Cited by 29 publications

References 57 publications

Local order in Cr-Fe-Co-Ni: Experiment and electronic structure calculations

Local order in Cr-Fe-Co-Ni: Experiment and electronic structure calculations

Thermophysical properties of Ni-containing single-phase concentrated solid solution alloys

Phase stability of ternary fcc and bcc Fe-Cr-Ni alloys

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