A new structural model for transition metal–metalloid glasses

Gaskell, Philip

doi:10.1038/276484a0

Cited by 235 publications

(111 citation statements)

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“…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.…”

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confidence: 78%

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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confidence: 78%

Design of Cu8Zr5-based bulk metallic glasses

Yang

Xia

Wang

et al. 2006

Applied Physics Letters

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“…Although significant progress has been made and provided insights into the atomic-level structure and short-to-mediumrange order in glasses [3][4][5][6][7][8][9][10][11][12][13][14] , the way of leading to the mediumrange order is still unclear [5][6][7][8][9][10] . Does a universal rule exist that nature follows to construct a glass structure as what has been discovered for crystals?…”

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confidence: 99%

Hidden topological order and its correlation with glass-forming ability in metallic glasses

Wang

et al. 2015

Nat Commun

116

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Unlike the well-defined long-range periodic order that characterizes crystals, so far the inherent atomic packing mode in glassy solids remains mysterious. Based on molecular dynamics simulations, here we find medium-range atomic packing orders in metallic glasses, which are hidden in the diffraction data in terms of structure factors or pair correlation functions. The analysis of the hidden orders in various metallic glasses indicates that the glassy and crystalline solids share a nontrivial structural homology in short-to-medium range, and the hidden orders are formulated by inheriting partial crystalline orders during glass formation. As the number of chemical components increases, more hidden orders are often developed in a metallic glass and entangled topologically. We use this phenomenon to explain the geometric frustration in glass formation and the glass-forming ability of metallic alloys.

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“…Many structural models have been proposed over the years, such as ''dense random packing'' of hard spheres [5] and the ''stereochemically designed'' model [6]. Although these early models significantly improved our understanding of atomic structures in MGs, especially for short-range order (SRO), they still have their own insufficiencies [7].…”

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confidence: 99%

Metallic Liquids and Glasses: Atomic Order and Global Packing

et al. 2010

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In this Letter, we have revealed the common structural behavior of metallic glasses through scrutinizing the evolution of pair distribution functions from metallic liquids to glasses and statistically analyzing pair distribution functions of 64 metallic glasses. It is found that the complex atomic configuration in metallic glasses can be interpreted globally as a combination of the spherical-periodic order and local translational symmetry. The implications of our study suggest that the glass transition could be visualized mainly as a process involving in local translational symmetry increased from the liquid to glassy states. DOI: 10.1103/PhysRevLett.105.155501 PACS numbers: 61.43.Dq, 61.43.Bn The atomic structure of metallic glasses (MGs) is a fundamental and intriguing issue in condensed-matter physics, due to its importance in understanding the glassforming mechanism and unique properties [1][2][3][4]. Many structural models have been proposed over the years, such as ''dense random packing'' of hard spheres [5] and the ''stereochemically designed '' model [6]. Although these early models significantly improved our understanding of atomic structures in MGs, especially for short-range order (SRO), they still have their own insufficiencies [7]. Recent studies confirm that the characteristics of medium-range order (MRO) clusters dictate the stability and mechanical properties of monolithic MGs [8][9][10][11], which have shed new light on our understanding of structural features at this length scale [7,[12][13][14]. By taking the earlier models further with advances in relevant experimental techniques and computational capacity, the idealized cluster packing schemes, such as efficient cluster packing on a facecentered cubic (fcc) lattice [12] and quasiequivalent clusters on an icosahedral packing [7], have been proposed and furthered our comprehension of the MRO. However, the latest finding indicated that the MRO in MGs can be described by packing of quasiequivalent clusters on a fractal network with a dimension (D f ) of 2.31 [14], implying that it is impossible to fill the real space in these amor phous solids by building blocks in a form of crystal (D f ¼ 3:0) or icosahedral-quasicrystal (D f ¼ 2:72) symmetry. The nature of atomic packing at the MRO scale or larger in MGs still remains mysterious [15].Glassy alloys are commonly considered as the state of ''frozen liquids''; nevertheless, their structure difference is obvious: A split in the second peak of the atomic-pair distribution function (PDF) curve, gðrÞ, for MGs, occurs with respect to that for liquids. Actually, the splitting of the second maximum of the gðrÞ curve into two subpeaks is recognized as a characteristic indication of amorphous solids [16], and its origin has been investigated extensively [17][18][19]. For example, Bennett proposed that the first subpeak at R 2 =R 1 ¼ ffiffiffi 3 p results from a continuum of configuration of two coplanar equilateral triangles sharing a common side, and the second one at R 3 =R 1 ¼ ffiffiffi 4 p originat...

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A new structural model for transition metal–metalloid glasses

Cited by 235 publications

References 7 publications

Design of Cu8Zr5-based bulk metallic glasses

Design of Cu8Zr5-based bulk metallic glasses

Hidden topological order and its correlation with glass-forming ability in metallic glasses

Metallic Liquids and Glasses: Atomic Order and Global Packing

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