Sluggish mobility and strong icosahedral ordering in Mg–Zn–Ca liquid and glassy alloys

Zhao, Yanyu; Lin, De-Ye; Chen, X.H.; Liu, Zhe; Hui, Xidong

doi:10.1016/j.actamat.2013.12.037

Cited by 22 publications

(14 citation statements)

References 40 publications

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“…52,61 Then, it can be inferred that icosahedral ordering should be the preferential structural feature in the Zn-centered clusters, which is well consistent with the results reported by Zhao. 25 The bond orientational order parameter 62 W 6 can be used as a quantitative measure of the icosahedral ordering, because its minimum value (−0.17) is obtained only by a perfect icosahedron. As shown in Figure 5d, the atoms that constitute the majority of the low-W 6 (more icosahedral-like) ones are precisely those with the Voronoi types mentioned above, further demonstrating the essential role of our identification of the icosahedral-like polyhedra.…”

Section: Local Structural Analysismentioning

confidence: 99%

Composition-Dependent Structural and Electronic Properties of Mg_95–xZn_xCa₅ Metallic Glasses: An Ab Initio Molecular Dynamics Study

Liu

et al. 2015

J. Phys. Chem. B

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Recent progress in the synthesis of Mg-based metallic glasses (MGs) has allowed them to be considered as potential candidates for biodegradable and bioabsorbable implant materials. In this work, we use the Mg-Zn-Ca system as a representative to investigate the effect of composition on the atomic-level structure and local chemical environment in Mg-based MGs from ab initio molecular dynamics simulations. The results suggest that the short-range order of Mg(95-x)Zn(x)Ca5 (x = 21, 25, 29, and 33) MGs is characterized by Zn-centered icosahedral and icosahedral-like clusters, which show an increasing number and a rising tendency to interpenetrate each other with the enrichment of Zn constituents. A considerable degree of charge transfer between Zn and the surrounding Mg/Ca atoms is observed through electronic structure and bonding character analysis. At Zn-rich compositions, a percolated Zn-Zn network extended throughout the entire sample is formed, upon which the accumulated charges around Zn atoms are associated into a continuous conductivity path. Such results may shed light on the improved corrosion resistance of the Zn-rich Mg-Zn-Ca MGs.

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Section: Local Structural Analysismentioning

confidence: 99%

Composition-Dependent Structural and Electronic Properties of Mg_95–xZn_xCa₅ Metallic Glasses: An Ab Initio Molecular Dynamics Study

Liu

et al. 2015

J. Phys. Chem. B

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“…Due to the potential large impact of these glasses, this has attracted substantial attention, but the structural studies of Mg-Zn-Ca metallic glasses are far from complete. Several recent works showed that the short-range order (SRO) in these glasses is formed to some extent with icosahedral and icosahedral-like structural units, 8,[11][12][13][14] but it is clear that distinguishing the subtle changes in SRO with glass composition is difficult. Based on ab initio molecular dynamics (MD) it was also proposed that a percolated network formed with Zn-centered structural units in Zn-rich Mg-Zn-Ca glasses (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…13 Much of this previous work relies on ab initio MD. 8,11,13,14 Ab initio MD has the great advantage that is free from a priori established assumptions about interatomic interactions, but the associated very high computational expense means that it is restricted to small models, typically a few hundred atoms. This prohibits the possibility of analysing the structure at larger length scales.…”

Section: Introductionmentioning

confidence: 99%

Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction

Gulenko

Chungong

Gao

et al. 2017

Phys. Chem. Chem. Phys.

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We use a combination of classical molecular dynamics simulation and neutron diffraction to identify the atomic structure of five different Mg-Zn-Ca bulk metallic glasses, covering a range of compositions with substantially different behaviour when implanted in vitro. There is very good agreement between the structures obtained from computer simulation and those found experimentally. Bond lengths and the total correlation function do not change significantly with composition. The zinc and calcium bonding shows differences between composition: the distribution of Zn-Ca bond lengths becomes narrower with increasing Zn content, and the preference for Zn and Ca to avoid bonding to themselves or each other becomes less strong, and, for Zn-Ca, transforms into a positive preference to bond to each other. This transition occurs at about the same Zn content at which the behaviour on implantation changes, hinting at a possible structural connection. A very broad distribution of Voronoi polyhedra are also found, and this distribution broadens with increasing Zn content. The efficient cluster packing model, which is often used to describe the structure of bulk metallic glasses, was found not to describe these systems well.

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“…Note that the expression in brackets in Equation (8) gives the total molar enthalpy difference between the quenched droplet at ambient temperature and the unmixed liquid at T = T con . The required formation enthalpy (for Al 3 Tb) is computed using a DFT approach (see Appendix C).…”

Section: Calorimetry Experimentsmentioning

confidence: 99%

“…Phase selection pathways in glass-forming metallic liquids are influenced by the development of short-and medium-range order [1][2][3][4][5][6][7][8][9][10], which contribute to local energetics and dynamics. Even in binary glass-forming systems, clear evidence of the influence of ordering in the liquid state has been reported [3][4][5][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Enthalpy of Mixing in Al–Tb Liquid

Zhou

Tackes

Napolitano

2017

Entropy

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Abstract:The liquid-phase enthalpy of mixing for Al-Tb alloys is measured for 3, 5, 8, 10, and 20 at% Tb at selected temperatures in the range from 1364 to 1439 K. Methods include isothermal solution calorimetry and isoperibolic electromagnetic levitation drop calorimetry. Mixing enthalpy is determined relative to the unmixed pure (Al and Tb) components. The required formation enthalpy for the Al 3 Tb phase is computed from first-principles calculations. Based on our measurements, three different semi-empirical solution models are offered for the excess free energy of the liquid, including regular, subregular, and associate model formulations. These models are also compared with the Miedema model prediction of mixing enthalpy.

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Sluggish mobility and strong icosahedral ordering in Mg–Zn–Ca liquid and glassy alloys

Cited by 22 publications

References 40 publications

Composition-Dependent Structural and Electronic Properties of Mg_95–xZn_xCa₅ Metallic Glasses: An Ab Initio Molecular Dynamics Study

Composition-Dependent Structural and Electronic Properties of Mg_95–xZn_xCa₅ Metallic Glasses: An Ab Initio Molecular Dynamics Study

Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction

Enthalpy of Mixing in Al–Tb Liquid

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Sluggish mobility and strong icosahedral ordering in Mg–Zn–Ca liquid and glassy alloys

Cited by 22 publications

References 40 publications

Composition-Dependent Structural and Electronic Properties of Mg95–xZnxCa5 Metallic Glasses: An Ab Initio Molecular Dynamics Study

Composition-Dependent Structural and Electronic Properties of Mg95–xZnxCa5 Metallic Glasses: An Ab Initio Molecular Dynamics Study

Atomic structure of Mg-based metallic glasses from molecular dynamics and neutron diffraction

Enthalpy of Mixing in Al–Tb Liquid

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Product

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Composition-Dependent Structural and Electronic Properties of Mg_95–xZn_xCa₅ Metallic Glasses: An Ab Initio Molecular Dynamics Study

Composition-Dependent Structural and Electronic Properties of Mg_95–xZn_xCa₅ Metallic Glasses: An Ab Initio Molecular Dynamics Study