Local icosahedral structures in binary-alloy clusters from molecular-dynamics simulation

Cozzini, Stefano; Ronchetti, Marco

doi:10.1103/physrevb.53.12040

Cited by 28 publications

(32 citation statements)

References 18 publications

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“…However, simpler systems should be of great interest, fundamentally as well as technologically, since they would facilitate the atomic-structure determination for a given BMG, which has been a long-standing problem. [12][13][14][15][16][17][18][19][20][21][22][23][24] Originally, the dense-random-packed model was used to describe metallic glasses. 25 This model is based on the assumption that the glass consists of a random arrangement of spherical atoms ͑hard spheres͒ of each element.…”

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confidence: 99%

Design of Cu8Zr5-based bulk metallic glasses

Yang

Xia

Wang

et al. 2006

Applied Physics Letters

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Basic polyhedral clusters have been derived from intermetallic compounds at near-eutectic composition by considering a dense packing and random arrangement of atoms at shell sites. Using such building units, bulk metallic glasses can be formed. Since the discovery of glassy systems, based on multicomponent alloys, in the early 1990s, bulk metallic glasses ͑BMGs͒ have been extensively studied because certain mechanical properties, such as strength, can be significantly improved over their crystalline counterparts. 1-11 BMGs produced so far usually contain three or more elements. 1-3 Until now, complex compositions have been considered necessary in order to inhibit crystallization of the liquid phase during cooling of the melt. However, simpler systems should be of great interest, fundamentally as well as technologically, since they would facilitate the atomic-structure determination for a given BMG, which has been a long-standing problem. [12][13][14][15][16][17][18][19][20][21][22][23][24] Originally, the dense-random-packed model was used to describe metallic glasses. 25 This model is based on the assumption that the glass consists of a random arrangement of spherical atoms ͑hard spheres͒ of each element. However, it has also been pointed out that localized, directional chemical bonding and the formation of groups of atoms are relevant factors to theories of glass formation and stability. 26 The local structure is well defined and similar to that of the crystalline form of the material. Recently, a topological model for metallic glass formation was proposed. 27,28 According to that model, a solute occupying either substitutional or interstitial sites in the host lattice can destabilize the lattice by producing a critical internal strain. Besides the structural models mentioned above, several criteria for structural stability of a BMG have been suggested: ͑1͒ large value of the reduced glass transition temperature T g / T l , where T g is the glass transition temperature and T l is the liquidus temperaure; 29 ͑2͒ three empirical rules for a large supercooled liquid region: ͑a͒ multicomponent system, ͑b͒ significant differences in atomic size, and ͑c͒ negative heats of mixing among the main constituent atoms; 1,3 ͑3͒ high gamma value, ␥ = T x / ͑T g + T l ͒, where T x is crystallization temperature; 30 ͑4͒ interaction between the Fermi surface and the Brillouin zone in a nearly-free-electron model; 31 ͑5͒ the critical concentration of a solute element required for amorphization decreases, reaches a minimum, and then increases with increasing ratio between the size of the solute and the solvent atoms; 27,32,33 ͑6͒ there is an optimum ratio R * between the size of the solute atom and the average size of the surrounding solvent atoms for dense packing. 28,34 In spite of the criteria mentioned above, the design of alloys with a high glass forming ability ͑GFA͒ remains to a large extent unpredictable due to lack of understanding of the local atomic structure. Although polyhedral clusters have been revealed in some met...

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Design of Cu8Zr5-based bulk metallic glasses

Yang

Xia

Wang

et al. 2006

Applied Physics Letters

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“…Furthermore, the center of icosahedra is a larger atom (A), which differs markedly from the structures shown in Figure 1. Several authors have noticed, however, that the lowest-energy structures of isolated binary clusters [16] as well as those in model binary glasses [15] are almost always distorted icosahedra with a smaller atom in the center of cage (S-ICO) rather than that with a larger atom in the center (L-ICO). Our results in Figure 2 seem to indicate that it is not always the general rule.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…A similar study has been already conducted by Cozzini and Ronchetti [16] using molecular dynamics. We use, instead, the modified space-fixed genetic algorithm developed for multi-component systems [17] in this work.…”

Section: Introductionmentioning

confidence: 86%

“…Cozzini and Ronchetti [16]. However, since they did not visualize the structures of the clusters in detail, we show the lowest-and the next-lowest-energy structures of A x B 13-x binary clusters when λ=0.7 in Figure 1.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…Several authors [16,21] have noted that the lowest energy of a 13-atom cluster with icosahedral structure is isolated from other higher energies with non-icosahedral structures by a large energy gap. Thus the icosahedral cluster not only has the lowest energy but is thermally very stable [22] which can be seen in the energy spectra of A 0 B 13 , A 13 B 0 and A 1 B 12 clusters 5 in Figure 3.…”

Section: Numerical Resultsmentioning

confidence: 99%

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Lowest-energy structures of 13-atom binary clusters: Do icosahedral clusters exist in binary liquid alloys?

Iwamatsu¹,

Lai²

2007

Journal of Non-Crystalline Solids

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Although the existence of 13-atom icosahedral clusters in one-component close-packed undercooled liquids was predicted more than half a century ago by Frank, the existence of such icosahedral clusters is less clear in liquid alloys. We study the lowest-energy structures of 13-atom A x B 13-x Lennard-Jones binary clusters using the modified space-fixed genetic algorithm and the artificial Lennard-Jones potential designed by Kob and Andersen. Curiously, the lowest-energy structures are non-icosahedral for almost all compositions. The role played by the icosahedral cluster in a binary glass is questionable. keyword: binary cluster icosahedral cluster, binary alloy, glass, undercooled liquid PACS 61.25. Mv, 61.43.Dq, 61.46.+w

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Local icosahedral structures in binary-alloy clusters from molecular-dynamics simulation

Cited by 28 publications

References 18 publications

Design of Cu8Zr5-based bulk metallic glasses

Design of Cu8Zr5-based bulk metallic glasses

Lowest-energy structures of 13-atom binary clusters: Do icosahedral clusters exist in binary liquid alloys?

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