The e/a values of ideal metallic glasses in relation to cluster formulae

Han, Guangbing; Qiang, Jianbing; Li, Fengwei; Yuan, Lang; Quan, Shiguan; Wang, Qing; Wang, Yingmin; Chen, Dong; Häußler, P.

doi:10.1016/j.actamat.2011.05.065

Cited by 79 publications

(66 citation statements)

References 29 publications

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“…In addition to atomic-level structure in amorphous alloys, the electronic structural basis of their properties need to be examined systematically in future work. Although previous work has explored various aspects such as the covalency, ionicity, density of states, and valence electron density in MGs, [109][110][111][112][113] ample room remains to quantitatively relate electronic structure to properties of amorphous alloys (such as GFA, ductility, liquid fragility etc.) and to the short-to-medium range topological and chemical order.…”

Section: -100mentioning

confidence: 99%

Computational modeling sheds light on structural evolution in metallic glasses and supercooled liquids

Ding

2017

npj Comput Mater

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This article presents an overview of three challenging issues that are currently being debated in the community researching on the evolution of amorphous structures in metallic glasses and their parent supercooled liquids. Our emphasis is on the valuable insights acquired in recent computational analyses that have supplemented experimental investigations. The first idea is to use the local structural order developed, and in particular its evolution during undercooling, as a signature indicator to rationalize the experimentally observed temperature-dependence of viscosity, hence suggesting a possible structural origin of liquid fragility. The second issue concerns with the claim that the average nearest-neighbor distance in metallic melts contracts rather than expands upon heating, concurrent with a reduced coordination number. This postulate is, however, based on the shift of the first peak maximum in the pair distribution function and an average bond length determined from nearest neighbors designated using a distance cutoff. These can instead be a result of increasing skewness of the broad first peak, upon thermally exacerbated asymmetric distribution of neighboring atoms activated to shorter and longer distances under the anharmonic interatomic interaction potential. The third topic deals with crystal-like peak positions in the pair distribution function of metallic glasses. These peak locations can be explained using various connection schemes of coordination polyhedra, and found to be present already in high-temperature liquids without hidden crystal order. We also present an outlook to invite more in-depth computational research to fully settle these issues in future, and to establish more robust structure-property relations in amorphous alloys.npj Computational Materials (2017) 3:9 ;

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Section: -100mentioning

confidence: 99%

Computational modeling sheds light on structural evolution in metallic glasses and supercooled liquids

Ding

2017

npj Comput Mater

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“…where The effective e/a and number of atoms (Z) in the unit cluster formula follow the relationship [25]:…”

Section: E/a and Cluster Formulaementioning

confidence: 99%

Revisiting Al-Ni-Zr bulk metallic glasses using the ‘cluster-resonance’ model

Qiang

Wang

et al. 2011

Chin. Sci. Bull.

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(x=1, 1.5, 2, 3) were designed in this work and the bulk metallic glass (BMG) formation of these compositions was investigated by copper mold suction casting. A centimeter-scale BMG sample was obtained for the Ni 4 Zr 9 Al 2 (Al 13.3 Ni 26.7 Zr 60 in atomic percent) composition. The thermal glass parameters for this BMG were determined to be ΔT x = 68 K, T rg = 0.579, and γ m = 0.689. Using the 'cluster-resonance' model for glass formation an optimal BMG composition was determined using the cluster formula [Ni 3 Zr 9 ](Al 2 Ni 1 ). . These complex alloys are based on the basic ternary systems of Al-TM-Zr (TM = Ni, Co, Cu) together with specific alloying substitutes [5,7,8]. A rationalization of the glass-forming abilities (GFAs) of Al-TM-Zr alloys is desirable to quantify complex BMG compositions. Disagreements exist with regard to experimental accounts of the GFA for fundamental ternary systems [9][10][11]. This study is devoted to a reexamination of the GFAs of Al-Ni-Zr alloys. We first use the 'cluster-plus-glue-atom' model [12,13] for BMG composition design. This model presents a semiphenomenological treatment of a BMG structure. An atomic cluster of specific topology, chemical composition and glue structure were used to establish the statistical composition of a BMG system. An ideal BMG assumes universal cluster formulae such as [cluster] 1 (glue atoms) x , with x=1 or 3 [13,14]. To determine the structural stability of the model structure we recently proposed a 'cluster-resonance' model by taking the coupling of long-range Friedel oscillations of valence electrons with the pair correlation function into consideration [15]. The composition design of Al-Ni-Zr BMG alloys is incorporated into the model that follows. The 'cluster-resonance' model and composition designAccording to Häussler et al. [16] the static atomic structure of an ideal amorphous state is in resonance with the longrange Friedel oscillations of valence electrons. The resonance results in spherical periodicity as shown by the peak (shell) oscillation with a certain period in the pair correlation function of an ideal amorphous state. The spherical periodicity gives an oscillation wavelength ( Fr ) in the form of

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“…3,4 Here, the cluster represents the 1st nearest-neighbor while the glue atoms represent the 2nd nearest-neighbor, which cover already the principal short-range order structural feature. It is interesting to notice that the compositions of good metallic glasses with high glass forming abilities are universally expressed by a simple cluster formula [cluster](glue atom) 1,3 , where one cluster is matched with 1 or 3 glue atoms.…”

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confidence: 99%