Atomistic theory for predicting the binary metallic glass formation

Li, J.H.; Dai, Yuyu; Cui, Yuanyuan; Liu, B.X.

doi:10.1016/j.mser.2010.09.002

Cited by 84 publications

(48 citation statements)

References 309 publications

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“…That the grain boundary term of the RNS could in fact have the lowest free energy of any other possible state suggests that there are positive heat of mixing systems in which an "amorphous" state is stable (due to its relatively lower heat of mixing). Interestingly, the idea of a stable amorphous phase is not new to this work [43], although the present RNS framework may provide a new way of looking at the development of amorphous alloys on the basis of their grain boundary segregation behavior. For example, in Fig.…”

Section: Amorphous Limitmentioning

confidence: 99%

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Stability of binary nanocrystalline alloys against grain growth and phase separation

2013

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Grain boundary segregation has been established through both simulation and experiments as a successful approach to stabilize nanocrystalline materials against grain growth. However, relatively few alloy systems have been studied in this context; these vary in their efficacy, and in many cases the stabilization effect is compromised by second phase precipitation. Here we address the open-ended design problem of how to select alloy systems that may be stable in a nanocrystalline state. We continue the development of a general "regular nanocrystalline solution" model to identify the conditions under which binary nanocrystalline alloy systems with positive heats of mixing are stable with respect to both grain growth (segregation removes the grain boundary energy penalty) and phase separation (the free energy of the nanocrystalline system is lower than the common tangent defining the bulk miscibility gap). We calculate a "nanostructure stability map" in terms of alloy thermodynamic parameters. Three main regions are delineated in these maps: one where grain boundary segregation does not result in a stabilized nanocrystalline structure, one in which macroscopic phase separation would be preferential (despite the presence of a nanocrystalline state stable against grain growth), and one for which the nanocrystalline state is stable against both grain growth and phase separation. Additional details about the stabilized structures are also presented in the map, which can be regarded as a tool for the design of stable nanocrystalline alloys. Atomistic simulations on nanocrystalline alloys show that structural stabilization is contingent upon the distribution and character of the solute atom. A certain minimum concentration of solute is often found to be necessary for grain size stabilization, as for various solute species in simulated copper [11][12][13][14][15][16][17]. The efficacy of different solute species is variable, and in some studies has been related to the size difference between solute and solvent atoms [11][12][13]. However, in these studies, the grain boundaries are manually decorated with solute atoms, which may represent artificial segregation states. There have been fewer simulation works on systems where segregation is thermodynamic (by, e.g., Monte Carlo methods) [16][17][18][19][20]. These suggest that equilibrium solute segregation lowers the grain boundary energy to varying degrees. Experimentally, a reduction in the propensity for grain growth in nanocrystalline materials has been observed in a variety of binary alloys [21][22][23][24][25][26][27][28][29][30][31]. There are many indications in experimental systems that there is a "preferred" grain size which emerges during processing which is closely linked to the solute content [2,24,30,32,33]; this is considered significant evidence for a thermodynamic contribution to stabilization. The grain size that is stable against coarsening is correlated to the solute concentration in these systems, but the system also often exhibits instabilities w...

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Section: Amorphous Limitmentioning

confidence: 99%

“…There are a number of approaches to estimate the GFR (i.e. size/structure difference, eutectic shape, and enthalpy models) [43], and the present RNS model offers another approach.…”

Section: Amorphous Limitmentioning

confidence: 99%

Stability of binary nanocrystalline alloys against grain growth and phase separation

2013

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“…The Ni-Nb type alloy has thanks to its easy and relatively inexpensive production proved to be an interesting and promising example of binary metallic glass. From the thermodynamic point of view, Ni-Nb binary alloys provide an ideal model system for the study of the GFA [4,15].…”

Section: Introductionmentioning

confidence: 99%

Study on crystallization phenomenon and thermal stability of binary Ni–Nb amorphous alloy

Lesz

Dercz

2016

J Therm Anal Calorim

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In this paper, a ribbon of binary Ni-Nb amorphous alloy was prepared by the melt spinning technique. Glass transition and crystallization phenomenon of the alloy were investigated by differential scanning calorimetry. Thermal properties of the ribbon of binary Ni-Nb upon heating and cooling were analysed by DTA at a heating/cooling rate of 0.5 K s -1 under the purified argon atmosphere. The thermal stability of Ni-Nb amorphous alloy was studied by using an X-ray diffractometer equipped with an in situ heating system. The structure and fracture morphology of the ribbons were examined by X-ray diffraction and scanning electron microscopy methods.

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“…It follows that the major competing phase of the amorphous phase is the terminal solid solution phase, whose structure is relatively simple. This viewpoint has been supported by a large number of experimental and theoretical studies [27,29,30]. Accordingly, the issue of predicting the favored glass formation compositions could be converted into an issue of comparing the stability of the amorphous phase versus the solid solution phase.…”

Section: Resultsmentioning

confidence: 99%

Predicting Composition Dependence of Glass Forming Ability in Ternary Al-Cu-Y System by Thermodynamic Calculation

Wang

Liu

et al. 2014

Metals

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Abstract:The composition dependence of glass forming ability in the ternary Al-Cu-Y system is predicted by thermodynamic calculations based on the Miedema's model and Alonso's method. By comparing the relative energetic status of the amorphous phase versus the solid solution phase, a hexagonal composition region that energetically favoring the metallic glass formation is predicted. The glass formation driving force and crystallization resistance are further calculated and the composition of Al72Cu10Y18 is pinpointed with the largest glass forming ability in the Al-Cu-Y system. The calculation results are well supported by the experimental observations reported in the literature.

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Atomistic theory for predicting the binary metallic glass formation

Cited by 84 publications

References 309 publications

Stability of binary nanocrystalline alloys against grain growth and phase separation

Stability of binary nanocrystalline alloys against grain growth and phase separation

Study on crystallization phenomenon and thermal stability of binary Ni–Nb amorphous alloy

Predicting Composition Dependence of Glass Forming Ability in Ternary Al-Cu-Y System by Thermodynamic Calculation

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