Ab initio simulation: The correlation between the local melt structure and segregation behavior of Fe, V, Ti and Si in liquid Al

Yang, Jian; Zhang, Jiao; Dai, Yong; Ma, Jianbo; Li, Faguo; Bian, Fenggang; Mi, Jiawei; Sun, Baode

doi:10.1016/j.commatsci.2015.05.033

Cited by 16 publications

(3 citation statements)

References 33 publications

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“…The polyhedron with index (34,65) is preferred when effective atomic size ratio between solute and solvent atoms, R * , is close to 0.732 [16] (in Ba rich melt, R * ≈ 0.756). Similar structures have been reported in 28 molten Al107Fe [48] and metallic glass Ni81B19 [16]. with the indices of (22,43,24), (12,43,34), (12,33,44,15), (33,54,15), and (12,43,44) as a function of x.…”

Section: Coordination Polyhedronssupporting

confidence: 81%

An ab initio molecular dynamics exploration of associates in Ba-Bi liquid with strong ordering trends

Shang

Kim

et al. 2020

Acta Materialia

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Abstracts:Fictive associates are widely used to describe and model liquid phases with strong ordering trends. However, little evidence is known about the assumed associates in most cases. In the present work, an ab initio molecular dynamics (AIMD) study is employed to investigate the characters of the Ba-Bi liquid, in which associates have been assumed in existing thermodynamic modeling. It is found that in the Ba rich melt, the Bi atoms are almost completely surrounded by Ba atoms. The Bi-centered coordination polyhedrons are strongly associated to crystalline structures of Ba5Bi3 and Ba4Bi3 with a longer lifetime than other polyhedrons during the AIMD simulations. In addition, these Bi-centered polyhedrons in Ba rich melt connect with each other through vertex, edge, face, and/or bipyramid sharing to form medium range orders (MRO). In the Bi rich melt, the Ba-centered polyhedrons also form MROs, but they are both structurally and compositionally diverse with a shorter lifetime. These findings from AIMD study provide evidences that there exist a strongly ordering Ba4Bi3 associate and a weakly ordering BaBi3 associate in the Ba-Bi liquid. The predicted enthalpy of mixing in the liquid agrees well with the results by the CALPHAD modeling in the literature. Keywords: Short range order, medium range order, molten structure, enthalpy of mixing of liquid, ab initio molecular dynamics 3 1.Introduction Recently, Lichtenstein et al. [1] reported the extremely low chemical activity of Ba (aBa) in the Bi rich melt by measuring the electromotive force (EMF) of the Ba-Bi alloys.For example, at the barium mole fraction xBa = 0.05, the aBa value is as low as 6.3×10 -16 at temperature T = 773 K; and aBa = 8.7×10 -12 at T = 1123 K. These EMF results indicate that there exist strong chemical affinity and short-range order between Ba and Bi, i.e., there are chemical associates [2][3][4] in the liquid.There are two major thermodynamic approaches to account for strong short-range ordering, i.e., (i) the quasichemical model using pair approximation [5] and (ii) the associate model assuming a mixture of liquid single element species and molecule-like associates [3,4]. In the associate model, the compositions of the associates are usually the same as those of the intermetallic compounds with high melting temperatures or highly negative values of enthalpy of mixing [3,4]. The associate model has been successfully applied to model thermodynamic properties of binary and multicomponent systems [2,3,[6][7][8][9][10][11][12].Atomic structures in molten or amorphous alloys are usually considered to be ordered in short up to medium range with the existence of hexagonal, pentagonal, and/or quadrangular bipyramid entities, such as in the molten Al [13], Ni [14], Zr [15], glass Zr80Pt20 [16], glass Al75Ni25 [16], and liquid/glass Cu-Zr [17]. Solute-solvent atomic network (e. g., in glass Ni63Nb37 [16] and liquid Ni3Al [18]) or connected pentagonal bi-pyramids (e.g., in molten Al3Cu[19]) can also form medium range orders (MRO). It has been observe...

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Section: Coordination Polyhedronssupporting

confidence: 81%

An ab initio molecular dynamics exploration of associates in Ba-Bi liquid with strong ordering trends

Shang

Kim

et al. 2020

Acta Materialia

Self Cite

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“…The Brillouin [31] zone of the supercell was sampled only by the Γ points. The initial liquid configuration was generated by relaxing all the atomic positions in the supercell for 6 ps at 1500 K. Subsequently, the temperature of liquid system was gradually decreased to 1290, 1170, 1050 and 930 K. The atomic densities of any liquid system at different temperatures were determined by only changing the size of the supercell box until the total external pressure was lower than ±0.2 GPa [32]. The densities of liquid X-containing (X = As, Bi, Cu, Fe) Sb-based alloys are tabulated in table 1.…”

Section: Computational Methodologymentioning

confidence: 99%

Ab initio molecular dynamics study of the local structures and migration behaviors of liquid Sb-based alloys

Li,

Feng

et al. 2023

J. Phys. D: Appl. Phys.

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High-purity Sb is widely applied in the semiconductor industry, infrared detection and non-volatile memory. An in-depth knowledge of the local structure and related properties in liquid Sb-based alloys proves to be highly advantageous in the purification of Sb. In this work, an ab initio molecular dynamics simulation was used to study the local structures, dynamical properties, electronic structures and migration behaviors of liquid X-containing (X = As, Bi, Cu, Fe) Sb-based alloys. Among these solute atoms, the distribution coefficient of As/Bi is much larger than that of Cu/Fe. The results showed that the local structures around As/Bi are looser than those around Cu/Fe. The local structure around As/Bi contains a higher fraction of low-index bond pairs than that around Cu/Fe, and its local topological order of triples is closer to pure Sb melt. The coordination polyhedrons using As/Bi as the centered atom have more relaxed short-range order clusters than those using Cu/Fe as the centered atom. Different local structures and chemical effects may lead to different migration behaviors of solute atoms in the Sb melt.

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“…Despite these progresses, the focus of present studies has mainly been on the element effect of Al and Fe on the local structure of Al-Fe melt. Clearly, insight into the dynamics and evolution of Al-Fe alloys melt from the perspective of temperature dependence is still lacking [10]. Here, we report a systematic work to probe the temperature dependence of evolution of atomic structure of Al-1.5wt% Fe (weight percentage) alloys melt cooled from 750 to 630°C, by means of synchrotron X-ray total scattering (SXTS) and empirical potential structure refinement (EPSR) method.…”

Section: Introductionmentioning

confidence: 99%

Revealing atomic structure evolution of an Al-1.5Fe alloy in the liquid state using X-ray total scattering and empirical potential structure refinement

Shi

Qin

Zhao

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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We used in-situ real-time synchrotron X-ray total scattering and empirical potential structure refinement method to study the evolution of atomic structure of an Al-1.5Fe alloy melt from 750°C to 630 °C. Detailed data normalization and analyses for the total scattering data were presented in order to achieve sensible atomic structure simulation using the empirical potential structure refinement (EPSR) method with constraints of R-factor is <10-3. Reliable construction of 3D atomic structure of Al-Fe melt in the temperature range reveals that more Al atoms coordinate Fe atoms and the Fe-centered clusters get more compact with the temperature decreases. More systematic work linking the liquid structure to the nucleation structure is under way.

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Ab initio simulation: The correlation between the local melt structure and segregation behavior of Fe, V, Ti and Si in liquid Al

Cited by 16 publications

References 33 publications

An ab initio molecular dynamics exploration of associates in Ba-Bi liquid with strong ordering trends

An ab initio molecular dynamics exploration of associates in Ba-Bi liquid with strong ordering trends

Ab initio molecular dynamics study of the local structures and migration behaviors of liquid Sb-based alloys

Revealing atomic structure evolution of an Al-1.5Fe alloy in the liquid state using X-ray total scattering and empirical potential structure refinement

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