Characterization of the free volume in a Zr45.0Cu39.3Al7.0Ag8.7 bulk metallic glass by reverse Monte Carlo simulation and density measurements

Zhang, Yue; Hahn, Horst

doi:10.1016/j.jnoncrysol.2010.09.028

Cited by 14 publications

(4 citation statements)

References 34 publications

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“…It can be revealed that the distribution of atoms in the "as-cast" state is inhomogeneous with more and less dense regions. Similar results obtained for structure modeling of Zr-based metallic glass have been also presented by Zhang and Hahn [31]. These results are in good agreement with Turnbull and Cohen [32] idea, which founded that the amorphous structure might contain dense packed and less dense packed atomic aggregates (clusters).…”

Section: Resultssupporting

confidence: 90%

Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

Babilas

2015

Materials Characterization

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Section: Resultssupporting

confidence: 90%

Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

Babilas

2015

Materials Characterization

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“…Free volume in metallic glasses can be characterized by positron-annihilation spectroscopy (PAS) [14], density measurements [21], and differential scanning calorimetry (DSC) [22]. Here we use the DSC method developed by Beukel and Sietsma [23].…”

Section: Free-volume Evolutionmentioning

confidence: 99%

Rolling-induced microstructure change in Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass

Zhou

Kong

et al. 2011

Chin. Sci. Bull.

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The microstructures and free-volume evolutions of as-cast and pre-annealed Zr 65 Al 7.5 Ni 10 Cu 12.5 Ag 5 bulk metallic glasses during rolling deformation have been investigated. No phase transformation is detected in the as-cast/rolled specimen. However, the structural stability of the glass against plastic deformation is worse after pre-annealing, indicated by nanocrystallization in preannealed/rolled specimens with large deformation degrees. Moreover, with increasing deformation degree, the free-volume content in a pre-annealed/rolled specimen increases at a lower average rate than that in an as-cast/rolled specimen. Bulk metallic glasses (BMGs) have attracted much attention because of their properties such as high fatigue strength, high hardness, good castability, and excellent wear and corrosion resistances [1][2][3][4][5][6][7][8]. However, during compressive or tensile tests at temperatures far below the glass-transition temperature, failure of BMGs usually occurs along a single shear band without much macroscopic plasticity. Their low global plasticity and ductility limit their applications as engineering materials [9], and much attention has been focused on their deformation and fracture mechanisms. Spaepen showed that plastic deformation in a metallic glass is realized by a series of atomic diffusional jumps associated with free volume [10]. The introduction of free volume into shear bands leads to a local lowering of the viscosity, and, as a result, an abrupt break takes places along the shear band. Obviously, the mechanical properties of metallic glasses are closely related to the free-volume content. Four methods can be used to change free-volume content: cooling the melt at different rates during solidification [11], annealing the metallic glass below the glass-transition temperature [12], reheating the metallic glass to above the glasstransition temperature and then cooling down quickly [13], and plastic deformation [14][15][16][17]. The principle behind these methods is that metallic glasses are thermodynamically metastable. Their structure can be changed from one state to another state by heating or mechanical deformation. Many studies have addressed the effects of plastic deformation on the free-volume content of metallic glasses [18][19][20], but very little attention has been paid to the dependence of freevolume evolution during deformation on the initial state of the glass. In this study, rolling deformation was performed on as-cast and pre-annealed Zr 65 Al 7.5 Ni 10 Cu 12.5 Ag 5 BMGs, and their free-volume content evolutions were investigated. Experimental procedureAlloy ingots of nominal composition Zr 65 Al 7.5 Ni 10 Cu 12.5 Ag 5 (atomic per cent) were prepared by arc melting a mixture of pure Zr (99.9%), Al (99.99%), Ni (99.99%), Cu (99.99%), and Ag (99.99%) under a Ti-gettered argon atmosphere. The ingots were inverted and remelted six times to ensure

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“…The revealing of the deformation mechanisms from the free volume aspect was expected. So far, although a number of experimental and theoretical investigations have been devoted to studying the free volumes of MGs [25,26,27], it is still a challenge to quantitatively or directly detect or characterize the free volumes, such a concept is ambiguous and elusive. Therefore, to understand the deformation mechanisms in terms of free volume is still a long-standing issue [27].…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneity of Free Volumes in Metallic Glasses under Tension

Wei

Wang

et al. 2018

Materials

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In this work, the deformation of Zr2Cu metallic glass (MG) under uniaxial tensile stress was investigated at the atomic level using a series of synchrotron radiation techniques combined with molecular dynamics simulation. A new approach to the quantitative detection of free volumes in MGs was designed and it was found that free volumes increase in the elastic stage, slowly expand in the yield stage, and finally reach saturation in the plastic stage. In addition, in different regions of the MG model, free volumes exhibited inhomogeneity under stress, in terms of size, density, and distribution. In particular, the expansion of free volumes in the center region was much more rapid than those in the other regions. It is interesting that the density of free volumes in the center region abnormally decreased with strain. It was revealed that the atomic-level stress between different regions may contribute to the inhomogeneity of free volumes under stress. In addition, the inhomogeneous change of free volumes during the deformation was confirmed by the evolution of local atomic shear strains in different regions. The present work provides in-depth insight into the deformation mechanisms of MGs.

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Characterization of the free volume in a Zr45.0Cu39.3Al7.0Ag8.7 bulk metallic glass by reverse Monte Carlo simulation and density measurements

Cited by 14 publications

References 34 publications

Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

Characterization of atomic-level structure in Fe-based amorphous and nanocrystalline alloy by experimental and modeling methods

Rolling-induced microstructure change in Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glass

Inhomogeneity of Free Volumes in Metallic Glasses under Tension

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