Icosahedral clustering in a supercooled liquid and glass

Kondo, Toshiharu; Tsumuraya, Kazuo

doi:10.1063/1.460106

Cited by 35 publications

(21 citation statements)

References 15 publications

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“…A common strategy is to study model systems with simple interactions, hoping that they will describe qualitatively the properties of real glasses. Thus, systems simulated with pair potentials show an increase of icosahedra during liquid cooling [4][5][6][7]. However, the structural properties depend strongly on the type of interatomic potential used [8], and some simulations indicate that the formation of icosahedra decreases when many-body effects or nonadditivity are included [9].…”

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confidence: 99%

Structure and Stability of an Amorphous Metal

Fuente

Soler

1998

Phys. Rev. Lett.

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Using molecular dynamics simulations, with a realistic many-body embedded-atom potential, and a novel method to characterize local order, we study the structure of pure nickel during the rapid quench of the liquid and in the resulting glass. In contrast with previous simulations with pair potentials, we find more crystalline order and fewer icosahedra for slower quenching rates, resulting in a glass less stable against crystallization. It is shown that there is not a specific amorphous structure, only the arrest of the transition from liquid to crystal, resulting in small crystalline clusters immersed in an amorphous matrix with the same structure of the liquid.PACS numbers: 61.43. Fs, 61.43.Bn, 81.40.Ef The detailed knowledge of the atomic structure is essential to understand the special properties of amorphous materials. There seems to be general agreement in that the basic process underlying the glass transition is the arrest of structural relaxations [1], but it is not clear to what extent this leads to new structural units. Very different structural models have been proposed [2], and some of them assume that the glass structure is essentially different from those of the liquid and the crystal. For close-packed systems, the icosahedron has been largely proposed as a characteristic configuration, which becomes predominant during liquid quenching. Another example is the polycluster model [3], in which the amorphization proceeds by the nucleation and growth of amorphous clusters within the liquid.However, like in liquids and defective solids, the lack of atomic periodicity makes the experimental determination of the structure a largely unsolved problem. Therefore, molecular dynamics simulations offer an invaluable complementary tool, although the simulated times are generally much shorter than the experimental quenches. A common strategy is to study model systems with simple interactions, hoping that they will describe qualitatively the properties of real glasses. Thus, systems simulated with pair potentials show an increase of icosahedra during liquid cooling [4][5][6][7]. However, the structural properties depend strongly on the type of interatomic potential used [8], and some simulations indicate that the formation of icosahedra decreases when many-body effects or nonadditivity are included [9]. Therefore, it is questionable to what extent these results can be extrapolated to real glasses.An alternate strategy is to focus on systems, like pure metals, whose natural relaxation times are so short that they can be actually simulated in the limit between glass formation and crystallization. Within this approach we show in this work that, in the case of a pure metal, there is no specific amorphous structure different from that of the liquid and the crystal, but only the arrest of the transition from one to the other. We also study the stability of the glass and, in contrast with recent works [4,10], show that it is more stable when quenched faster.Although the experimental quenching rates required to form thei...

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confidence: 99%

Structure and Stability of an Amorphous Metal

Fuente

Soler

1998

Phys. Rev. Lett.

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“…The systems simulated with pair potentials show an increase in the number of icosahedra during liquid cooling [23][24][25][26]. Therefore, the embedded-atom method (EAM) potential [27], which has been successfully applied to a wide range of aspects of the liquid and amorphous states, is adopted in the present simulations [28][29][30][31][32][33].…”

Section: Simulation Methodsmentioning

confidence: 99%

Atomic packing and short-to-medium range order evolution of Zr-Pd metallic glass

Liu

Zhang

et al. 2011

Chin. Sci. Bull.

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A larger-scale Zr 70 Pd 30 alloy system has been simulated using molecular dynamics (MD) to investigate structure evolution in Zr 70 Pd 30 . In the Zr-Pd binary system, the nature of the amorphous-to-quasicrystalline phase transition has been clarified [4,5]. However, the characteristic structure in the Zr 70 Pd 30 MGs is currently unknown. We also do not know whether the structures of Zr 70 Pd 30 MGs directly affect the transition into the quasicrystalline phase. In the present study, the transition of the Zr 70 Pd 30 alloy from the supercooled liquid to the solid is simulated using molecular-dynamics (MD). The structure of the Zr 70 Pd 30 metallic glass is investigated in detail by means of the pair distribution function (PDF), pair analysis method (PA) [6,7] and Voronoi polyhedron analysis method. Based on the hypothesis that linking icosahedra can form the quasicrystalline phase, there has been considerable interest in the icosahedral medium range ordering (IMRO) of , which probably affects the glass formability as well as the mechanical properties, including Young's modulus and shear banding resistance [14]. Recently, some models for IMRO in MGs have been suggested by experimental and computational studies [15][16][17][18][19][20][21][22].

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“…In each of the RMC simulations for Sampl-10 and -20, the experimental ''total PDF'' was used as a reference PDF for the structure refinement. In order to know local atomic coordinations, the Voronoi polyhedral analysis 23) was used for each of the final RMC simulated structure. Details of the electron diffraction PDF analysis, the RMC simulation and the Voronoi analysis for amorphous alloys are written elsewhere.…”

Section: Tem X-ray and Electron Diffractionmentioning

confidence: 99%

Local Atomic Structures of Amorphous Nd4.5Fe77B18.5 Alloys Formed under Different Cooling Rates and Their Relations to the Structures in the Early Stage of Crystallization

et al. 2003

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A difference of amorphous structures of magnetic Nd 4:5 Fe 77 B 18:5 alloys formed under two different cooling rates was investigated by means of electron microscopy, electron diffraction and X-ray diffraction techniques. In spite of no appreciable difference in the high resolution electron microscope images, an atomic structural difference especially in the B-centered polyhedral structures was found in these specimens in their as-formed states. The effect of the initial local structure difference on the process of primary crystallization in these alloys on annealing was discussed.

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Icosahedral clustering in a supercooled liquid and glass

Cited by 35 publications

References 15 publications

Structure and Stability of an Amorphous Metal

Structure and Stability of an Amorphous Metal

Atomic packing and short-to-medium range order evolution of Zr-Pd metallic glass

Local Atomic Structures of Amorphous Nd<SUB>4.5</SUB>Fe<SUB>77</SUB>B<SUB>18.5</SUB> Alloys Formed under Different Cooling Rates and Their Relations to the Structures in the Early Stage of Crystallization

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