Non-Stoichiometry and Calphad Modeling of Frank-Kasper Phases

Joubert, Jean-Marc; Crivello, Jean-Claude

doi:10.3390/app2030669

Cited by 24 publications

(9 citation statements)

References 58 publications

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“…This question of so-called site preference 1 was discussed, for example, in Refs. [16,17,[82][83][84][85][86][87]. Upon adding a third element C to a Laves AB 2 , i.e., moving into the ternary system A-B-C, C may substitute either A or B to form a solid solution of the general formula (A 1-x C x )(B 1-y C y ) 2 , if we, for a moment neglect the possibility of A and B occupying the opposite sublattices.…”

Section: Stability and Site Preferencementioning

confidence: 99%

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

2020

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Laves phases with their comparably simple crystal structure are very common intermetallic phases and can be formed from element combinations all over the periodic table resulting in a huge number of known examples. Even though this type of phases is known for almost 100 years, and although a lot of information on stability, structure, and properties has accumulated especially during the last about 20 years, systematic evaluation and rationalization of this information in particular as a function of the involved elements is often lacking. It is one of the two main goals of this review to summarize the knowledge for some selected respective topics with a certain focus on non-stoichiometric, i.e., non-ideal Laves phases. The second, central goal of the review is to give a systematic overview about the role of Laves phases in all kinds of materials for functional and structural applications. There is a surprisingly broad range of successful utilization of Laves phases in functional applications comprising Laves phases as hydrogen storage material (Hydraloy), as magneto-mechanical sensors and actuators (Terfenol), or for wear- and corrosion-resistant coatings in corrosive atmospheres and at high temperatures (Tribaloy), to name but a few. Regarding structural applications, there is a renewed interest in using Laves phases for creep-strengthening of high-temperature steels and new respective alloy design concepts were developed and successfully tested. Apart from steels, Laves phases also occur in various other kinds of structural materials sometimes effectively improving properties, but often also acting in a detrimental way.

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Section: Stability and Site Preferencementioning

confidence: 99%

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

2020

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“…Three techniques are now described that can be combined to study the phenomenon described in the present paper (for more details see [2]). …”

Section: Experimental Techniques and Methodologymentioning

confidence: 99%

Irregular Homogeneity Domains in Ternary Intermetallic Systems

2015

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Abstract:Ternary intermetallic A-B-C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds ABx, ACx and BCx with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe-Nb-Zr, Hf-Mo-Re, Hf-Re-W, Mo-Re-Zr, Re-W-Zr, Cr-Mn-Si, Cr-Mo-Re, and Mo-Ni-Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co-Cr-Re and Fe-Nb-Zr systems.

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“…To date, the vast majority of ab initio total energy studies have considered only configurations in which sublattice sites were fully occupied by a single atomic species 5–19 , in particular with regard to Frank-Kasper structures 20 . When mixed occupancy of sublattice sites was considered it was only to the extent as necessitated by the cluster expansion method, say when nearest neighbor interactions between sites of the same type needed to be evaluated, such as is the case in the σ structure 21–24 .…”

Section: Introductionmentioning

confidence: 99%

Effect of mixed partial occupation of metal sites on the phase stability of γ-Cr23−xFe x C6 (x = 0–3) carbides

Souissi

Sluiter

Matsunaga

et al. 2018

Sci Rep

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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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Non-Stoichiometry and Calphad Modeling of Frank-Kasper Phases

Cited by 24 publications

References 58 publications

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

Laves phases: a review of their functional and structural applications and an improved fundamental understanding of stability and properties

Irregular Homogeneity Domains in Ternary Intermetallic Systems

Effect of mixed partial occupation of metal sites on the phase stability of γ-Cr23−xFe x C6 (x = 0–3) carbides

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