The local structure of molten Ni 1−x Al x : An ab initio molecular dynamics study

Ma, Jianbo; Chen, Shihao; Dai, Yong; Zhang, Jiao; Yang, Jian; Wang, Jun; Sun, Baode

doi:10.1016/j.jnoncrysol.2015.05.025

Cited by 13 publications

(6 citation statements)

References 31 publications

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“…For the purpose to distinguish coordination polyhedrons, a set of index, defined as (l2,l3,…lj) [13,18], is employed, as inspired from the definition of Voronoi index [42]. Index "lj" denotes the total number of the 1jxx-type bonded-pairs around the central atom.…”

Section: Characterization Of Coordination Polyhedronmentioning

confidence: 99%

“…These structural features found in the Ba-Bi liquid are expected to occur in other liquids with strong chemical affinity between unlike species. For example of an A-B binary with A rich MRO in A rich melt and B rich MRO in B rich melt, these MROs can be the connections of the solute-centered polyhedrons [16] or the solute-solvent network [16,18]. In the Al-Ni system, it was reported that there are string-like MRO in Al rich side (in glass Al75Ni25) [16] and solute-solvent network MRO in Ni rich side (in molten Ni3Al) [18].…”

Section: Associatesmentioning

confidence: 99%

“…For example of an A-B binary with A rich MRO in A rich melt and B rich MRO in B rich melt, these MROs can be the connections of the solute-centered polyhedrons [16] or the solute-solvent network [16,18]. In the Al-Ni system, it was reported that there are string-like MRO in Al rich side (in glass Al75Ni25) [16] and solute-solvent network MRO in Ni rich side (in molten Ni3Al) [18]. For the Al-Co system, there are MROs in both Al-rich and Co-rich melts due to the noticeable pre-peaks on the plots of structure factors [45].…”

Section: Associatesmentioning

confidence: 99%

“…Pre-peak on the left of the static SF indicates that there are large-scale repeated structures in the melt [43,44], namely MRO. It has been reported that there is noticeable SF pre-peak for Ni rich melts (or amorphous) (e.g., Ni-Al [18,45], Ni-Ti [23], Ni-Nb [23], Ni-Ta [23], and Ni-Pt [38]) and Al rich melts (e.g., Al-Ni [45,46], Al-Co [45], and Al-Fe [47]). The pronounced peak located near q ≈ 1.37 Å -1 on SBiBi(q) when x = 0.10 and 0.43 is noticeable (Figure 4b and c).…”

Section: Energy Analysismentioning

confidence: 99%

“…Those BAPs inherit some features of the compounds (Table 1. ), such as the high coordination numbers (16)(17)(18) for compounds, about 13-16…”

Section: Coordination Polyhedronsmentioning

confidence: 99%

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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: Characterization Of Coordination Polyhedronmentioning

confidence: 99%

Section: Associatesmentioning

confidence: 99%

Section: Associatesmentioning

confidence: 99%

Section: Energy Analysismentioning

confidence: 99%

“…Those BAPs inherit some features of the compounds (Table 1. ), such as the high coordination numbers (16)(17)(18) for compounds, about 13-16…”

Section: Coordination Polyhedronsmentioning

confidence: 99%

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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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Effect of Rare Earth Ce on Structure and Properties in 7CrSiMnMoV Die Steel Castings

Long,

Li,

Zeng

et al. 2024

steel research int.

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In this study, rare earth (RE) Ce is used to modify the interaction between atoms in 7CrSiMnMoV die steel castings. The tensile properties are performed, and strengthening mechanism are analyzed by investigated fracture surface, and microstructure by optical microscopy (OM) and scanning electron microscope‐energy dispersive spectrometer (SEM‐EDS). And ab initio molecular dynamics (AIMD) is used to simulate the effect of the Ce element on the local atomic structure of the FeCeC system alloy steel. The results indicate the strength can increase from 722.55 to 1074.27 MPa, and the elongation can increase from 24.86% to 44.22% with a RE Ce concentration of 0.009%. It is attributed to that doping of Ce can inhibit the formation of network eutectic cementite, refine the lamellar spacing of pearlite, and even form granular cementite and martensite structures. AIMD simulation results show that C atoms tend to be surrounded by Fe, and the strong chemical bonds of FeC make the Fe‐centered C more stable with an increase in RE Ce concentration. And doping Ce can introduce new local topological and chemical orderings such that the FeCFe triplets predominantly form small and big angles shifting from near 75° and 136° to 47° and 81°, respectively.

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Intermetallics in Ni–Al Binary Alloys: Liquid Structural Origin

Zhao

Cao

Zeng

et al. 2022

Metall Mater Trans A

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The local structure of molten Ni 1−x Al x : An ab initio molecular dynamics study

Cited by 13 publications

References 31 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

Effect of Rare Earth Ce on Structure and Properties in 7CrSiMnMoV Die Steel Castings

Intermetallics in Ni–Al Binary Alloys: Liquid Structural Origin

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