Partial molar volumes and size factor data for alloy constituents of stainless steel

Straalsund, J.L.; Bates, J.F.

doi:10.1007/bf02644119

Cited by 29 publications

(12 citation statements)

References 2 publications

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“…Such a conclusion should, however, be contrasted with the lack of consistent behavior for single solutes in defect-free Fe, as discussed earlier. Indeed, experimental results 80 find Ni to be undersized and Cr oversized in an austenitic Fe-Cr-Ni alloy, consistent with the pure elements. This may account for the earlier attempts to suggest a positive binding of Ni to interstitial defects which our results show is an unwarranted conclusion.…”

Section: A Defect-solute Interactionsupporting

confidence: 53%

Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

2012

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We present results of an extensive set of first-principles density functional theory calculations of point defect formation, binding, and clustering energies in austenitic Fe with dilute concentrations of Cr and Ni solutes. A large number of possible collinear magnetic structures were investigated as appropriate reference states for austenite. We found that the antiferromagnetic single-and double-layer structures with tetragonal relaxation of the unit cell were the most suitable reference states and highlighted the inherent instabilities in the ferromagnetic states. Test calculations for the presence and influence of noncollinear magnetism were performed but proved mostly negative. We calculate the vacancy formation energy to be between 1.8 and 1.95 eV. Vacancy cluster binding was initially weak at 0.1 eV for divacancies but rapidly increased with additional vacancies. Clusters of up to six vacancies were studied and a highly stable octahedral cluster and stacking fault tetrahedron were found with total binding energies of 2.5 and 2.3 eV, respectively. The 100 dumbbell was found to be the most stable self-interstitial with a formation energy of between 3.2 and 3.6 eV and was found to form strongly bound clusters, consistent with other fcc metals. Pair interaction models were found to be capable of capturing the trends in the defect cluster binding energy data. Solute-solute interactions were found to be weak in general, with a maximal positive binding of 0.1 eV found for Ni-Ni pairs and maximum repulsion found for Cr-Cr pairs of −0.1 eV. Solute cluster binding was found to be consistent with a pair interaction model, with Ni-rich clusters being the most stable. Solute-defect interactions were consistent with Ni and Cr being modestly oversized and undersized solutes, respectively, which is exactly opposite to the experimentally derived size factors for Ni and Cr solutes in type 316 stainless steel and in the pure materials. Ni was found to bind to the vacancy and to the 100 dumbbell in the tensile site by 0.1 eV and was repelled from mixed and compressive sites. In contrast, Cr showed a preferential binding to interstitials. Calculation of tracer diffusion coefficients found that Ni diffuses significantly more slowly than both Cr and Fe, which is consistent with the standard mechanism used to explain radiation-induced segregation effects in Fe-Cr-Ni austenitic alloys by vacancy-mediated diffusion. Comparison of our results with those for bcc Fe showed strong similarity for pure Fe and no correlation with dilute Ni and Cr.

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Section: A Defect-solute Interactionsupporting

confidence: 53%

Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

2012

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“…These results are not, however, in agreement with the experimentally derived size factors for Ni and Cr solutes in type 316 SS and in the pure materials. 57 (6) A few differences can be reported for the mixed dumbbells compared to 100 Fe-Fe dumbbells. In particular, when located next to the Ni atom of the [100] Fe-Ni dumbbell, Ni atoms tend to decrease the formation energy.…”

Section: Discussionmentioning

confidence: 99%

“…Fe Ni Cr 57 for which Ni is found to be undersized. These results are not, however, necessarily in contradiction since the experimental results were obtained at high temperatures.…”

Section: Alloying Elementsmentioning

confidence: 99%

First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

Piochaud¹,

Klaver²,

Adjanor³

et al. 2014

Phys. Rev. B

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The influence of the local environment on vacancy and self-interstitial formation energies has been investigated in a face-centered-cubic (fcc) Fe-10Ni-20Cr model alloy by analyzing an extensive set of first-principle calculations based on density functional theory. Chemical disorder has been considered by designing special quasirandom structures and four different collinear magnetic structures have been investigated in order to determine a relevant reference state to perform point defect calculations at 0 K. Two different convergence methods have also been used to characterize the importance of the method on the results. Although our fcc Fe-10Ni-20Cr would be better represented in terms of applications by the paramagnetic state, we found that the antiferromagnetic single-layer magnetic structure was the most stable at 0 K and we chose it as a reference state to determine the point defect properties. Point defects have been introduced in this reference state, i.e., vacancies and Fe-Fe, Fe-Ni, Fe-Cr, Cr-Cr, Ni-Ni, and Ni-Cr dumbbell interstitials oriented either parallel or perpendicular to the single layer antiferromagnetic planes. Each point defect studied was introduced at different lattice sites to consider a sufficient variety of local environments and analyze its influence on the formation energy values. We have estimated the point defect formation energies with linear regressions using variables which describe the local environment surrounding the point defects. The number and the position of Ni and Cr first nearest neighbors to the point defects were found to drive the evolution of the formation energies. In particular, Ni is found to decrease and Cr to increase the vacancy formation energy of the model alloy, while the opposite trends are found for the dumbbell interstitials. This study suggested that, to a first approximation, the first nearest atoms to point defects can provide reliable estimates of point defect formation energies.

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“…With low carbon contents (say, up to 0.5 pct C), however, the amounts of cementite and other carbides remain quite small and (a) (b) Fig. 6-Experimental [18,59,[71][72][73][74] vs calculated densities of (a) ferrite and (b) austenite. cause a negligible error to the density data of ferrite.…”

Section: A Density Of Liquidmentioning

confidence: 99%

“…In ferrite and austenite, however, the effects of other important solutes, Si, Mn, Cr, Mo, and Ni, have been taken into account as shown in the following. The solute effects of Si, Mn, Cr, Mo, and Ni upon the density of ferrite and austenite were evaluated using the density data of Smithells, [18] Richter, [59,71] Straalsund and Bates [72] and the Metals Handbook, [73] the linear thermal expansion data of Smithells [18] and Richter, [59] and the lattice spacing data of Pearson. [74] (It is worth noticing that References 18, 59, and 71 partly dealt with the same steel compositions and data, but in the present analysis, only one set of data for a specific steel composition was taken into account.)…”

Section: A Density Of Liquidmentioning

confidence: 99%

Calculation of solidification-related thermophysical properties for steels

Miettinen¹

1997

Metall Mater Trans B

190

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Special algorithms have been developed to calculate important solidification-related thermophysical properties: enthalpy and enthalpy-related data (i.e., specific and latent heat), density, and thermal conductivity for low-alloyed and stainless steels. The algorithms are heavily based on the use of earlier developed phase transformation models, an interdendritic solidification model (IDS), and an austenite decomposition model (ADC), which solve, as a function of temperature, the phase fractions and compositions needed in these calculations. As a result, the thermophysical properties can be calculated at any temperature, from 1600 ЊC to 25 ЊC, taking into account the discontinuities caused by special phase transformations (i.e., ferritic, austenitic and peritectic solidification, ferrite/austenite transformation, and austenite decomposition to various structures) influenced by the steel grade and the cooling conditions.

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Partial molar volumes and size factor data for alloy constituents of stainless steel

Cited by 29 publications

References 2 publications

Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

Calculation of solidification-related thermophysical properties for steels

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