An atomistic study of the structural changes in a Zr–Cu–Ni–Al glass-forming liquid on vitrification monitored in-situ by X-ray diffraction and molecular dynamics simulation

Abstract

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The Modified Random Network (MRN) Model within the Configuron Percolation Theory (CPT) of Glass Transition

“…It was demonstrated for several metallic glass-forming liquids that the rate of this structural ordering as a function of temperature correlates with the kinetic fragility of the liquid, demonstrating a structural basis for fragility [69]. Moreover, it was shown that the fragility is a sign of instability of short and medium range order in liquids with molecular dynamic simulation supporting observed structure variation [70]. Thus, the glass transition although being a kinetically controlled process [28] is nevertheless linked to structural rearrangements [31] and has thermodynamically related features and similarity to second-order thermodynamic phase transformations [71].…”

“…Additional value can be also brought by analyzing the actual MRO structure of glasses such of the facets of clusters formed in the glass transition process analysis based on X-ray diffraction patterns [67]. There is a link between fragility and internal structural changes observed on cooling of some liquids [64,[68][69][70]. Synchrotron X-ray scattering studies have shown an increasing degree of short-and medium-range order that develops with increased supercooling, and the analysis of the atomic and electronic structure of the alloy in liquid and glassy states revealed the formation of chemical short-range order in the temperature range corresponding to such a non-Arrhenius behavior [68].…”

Structural Changes in Metallic Glass-Forming Liquids on Cooling and Subsequent Vitrification in Relationship with Their Properties

“…The difference in the specific heat capacity ( C p ) at T g between the liquid and glassy phases is also used to estimate fragility [ 161 ]. Δ C p l–g values (difference between C p of liquid ( C p l ) and glassy ( C p g ) phases) of 10 and 17 J/mol⋅K for Zr 55 Cu 30 Ni 5 Al 10 and Pd 42.5 Cu 30 Ni 7.5 P 20 alloys, respectively [ 152 ], are also in line with the fragility parameters of these alloys.…”

“…Seven Gaussian function peaks describe well the entire shape of G(R) function (oscillating near 0 while PDF (R) oscillates near 1) as shown in Figure 8 . As in case of the Pd-Cu-Ni-P glass-forming alloy discussed above the first and second G(R) maxima of Zr 55 Cu 30 Ni 5 Al 10 consist of two peaks (P1 and P2), especially at a low temperature [ 152 ]. The first peak (P1) in the first coordination shell is related to the nearest Zr-(Cu,Ni) distances.…”

On Structural Rearrangements during the Vitrification of Molten Copper

“…Thus, the FSDM contains information on structural changes in amorphous materials at the T g . A method for determining the T g is hence to assign it to the onset of kink of FSDM and the proposed method is more sensitive than the Wendt-Abraham criterion based on the analysis of diffraction peaks [18,47,48]. It is also notable that the Wendt-Abraham criterion supposed that at T g the equality holds Φ T g = 0.15 [38].…”