Structural feature of Cu64Zr36 metallic glass on nanoscale: Densely-packed clusters with loosely-packed surroundings

Feng, Shidong; Qi, Li; Wang, L.M.; Yu, Pengfei; Zhang, S.L.; Ma, Mingzhen; Zhang, X.Y.; Qin, Jing; Ngai, K. L.; Greer, A.L.; Li, G.; Liu, R.P.

doi:10.1016/j.scriptamat.2015.12.038

Cited by 41 publications

(6 citation statements)

References 25 publications

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“…Shear transformations may have strong dependence on the preparation history of the sample. Our previous work proved that higher initial quenching temperatures or cooling rates decrease short range order and clusters in MGs38. Smaller clusters prevail in liquids at higher initial quenching temperature, and are passed into the glass by fast quenching.…”

Section: Resultsmentioning

confidence: 80%

Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

Feng

Jiao

Qin

et al. 2016

Sci Rep

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Structural evolution in nanoscale Cu50Zr50 metallic glasses during high-pressure torsion is investigated using molecular dynamics simulations. Results show that the strong cooperation of shear transformations can be realized by high-pressure torsion in nanoscale Cu50Zr50 metallic glasses at room temperature. It is further shown that high-pressure torsion could prompt atoms to possess lower five-fold symmetries and higher potential energies, making them more likely to participate in shear transformations. Meanwhile, a higher torsion period leads to a greater degree of forced cooperative flow. And the pronounced forced cooperative flow at room temperature under high-pressure torsion permits the study of the shear transformation, its activation and characteristics, and its relationship to the deformations behaviors. This research not only provides an important platform for probing the atomic-level understanding of the fundamental mechanisms of high-pressure torsion in metallic glasses, but also leads to higher stresses and homogeneous flow near lower temperatures which is impossible previously.

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Section: Resultsmentioning

confidence: 80%

Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

Feng

Jiao

Qin

et al. 2016

Sci Rep

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“…6(b), the initial stages of STZs occur at the strain 0.062 and distribute randomly within the Mg 66 Zn 30 Ca 3 Sr 1 . Feng 61 has concluded that the random distribution of STZs is primarily due to the structural heterogeneity of BMGs at the initial state. At the strain 0.089, as indicating in Fig.…”

Section: Resultsmentioning

confidence: 99%

Effects of Strontium incorporation to Mg-Zn-Ca biodegradable bulk metallic glass investigated by molecular dynamics simulation and density functional theory calculation

Sun

Yang

et al. 2020

Sci Rep

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Molecular dynamics (MD) simulation and density functional theory (DFT) calculations were used to predict the material properties and explore the improvement on the surface corrosion resistance for the Mg 66 Zn 30 Ca 3 Sr 1 bulk metallic glass (BMG). The Mg 66 Zn 30 Ca 4 BMG was also investigated to realize the influence of the addition of Sr element on the material behaviors of Mg 66 Zn 30 Ca 4. The Mg-Zn-Ca-Sr parameters of the next nearest-neighbor modified embedded atom method (2NN MEAM) potential were first determined by the guaranteed convergence particle swarm optimization (GCPSO) method based on the reference data from the density functional theory (DFT) calculation. Besides, using the 2NN MEAM parameters of the Mg-Zn-Ca-Sr system, the structures of Mg 66 Zn 30 Ca 4 and Mg 66 Zn 30 Ca 3 Sr 1 were predicted by the simulated-annealing basin-hopping (SABH) method. The local atomic arrangements of the predicted BMG structures are almost the same as those measured in some related experiments from a comparison with the calculated and experimental X-ray diffraction (XRD) profiles. Furthermore, the HA index analysis shows that the fractions of icosahedra-like local structures are about 72.20% and 72.73% for Mg 66 Zn 30 Ca 4 and Mg 66 Zn 30 Ca 3 Sr 1 , respectively, indicating that these two BMG structures are entirely amorphous. The uniaxial tensile MD simulation was conducted to obtain the stress-strain relationship as well as the related mechanical properties of Mg 66 Zn 30 Ca 4 and Mg 66 Zn 30 Ca 3 Sr 1. Consequently, the predicted Young's moduli of both BMGs are about 46.4 GPa, which are very close to the experimental values of 48.8 ± 0.2 and 49.1 ± 0.1 GPa for Mg 66 Zn 30 Ca 4 and Mg 66 Zn 30 Ca 3 Sr 1 , respectively. However, the predicted strengths of Mg 66 Zn 30 Ca 4 and Mg 66 Zn 30 Ca 3 Sr 1 are about 850 and 900 MPa, both are slightly higher than the measured experimental values about 747 ± 22 and 848 ± 21 MPa for Mg 66 Zn 30 Ca 4 and Mg 66 Zn 30 Ca 3 Sr 1. Regarding the thermal properties, the predicted melting temperature of Mg 66 Zn 30 Ca 3 Sr 1 by the square displacement (SD) profile is about 620 K, which is very close to the experimental melting temperature of about 613 K. The self-diffusion coefficients of Mg, Zn, Ca, and Sr elements were also calculated for temperatures near their melting points by means of the Einstein equation. The methodology can determine the diffusion barriers for different elements by utilizing these diffusion coefficients resulting in a fact that the diffusion barriers of Ca and Sr elements of Mg 66 Zn 30 Ca 3 Sr 1 are relatively high. For the electronic properties predicted by the DFT calculation, the projected density of states (PDOS) profiles of surface Mg, Zn, Ca, and Sr elements clearly show that the addition of Sr into Mg 66 Zn 30 Ca 4 effectively reduces the s and p orbital states of surface Mg and Zn elements near the Fermi level, particularly the p orbits, which suppresses the electron transfer as well as increases the surface corrosion resistance of Mg 66 Zn 30 Ca...

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“…In analogy to the crystalline metals, the physical and mechanical properties of metallic glasses are thought to be closely related to some kind of structural defects. In a metallic glass, the random close packed arrangement of atoms leads to some relatively "loose" and "dense" sites, which has been observed extensively by experiments and numerical simulations (Feng et al, 2016;Tsai et al, 2017;Yang et al, 2012b). A loose or dense site may be regarded as a defect, which corresponds to extra free volume or anti-free volume.…”

Section: Concept Of Defect Sitesmentioning

confidence: 97%

A hierarchically correlated flow defect model for metallic glass: Universal understanding of stress relaxation and creep

Hao

Lyu

Pineda

et al. 2022

International Journal of Plasticity

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Structural feature of Cu64Zr36 metallic glass on nanoscale: Densely-packed clusters with loosely-packed surroundings

Cited by 41 publications

References 25 publications

Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

Structural evolution of nanoscale metallic glasses during high-pressure torsion: A molecular dynamics analysis

Effects of Strontium incorporation to Mg-Zn-Ca biodegradable bulk metallic glass investigated by molecular dynamics simulation and density functional theory calculation

A hierarchically correlated flow defect model for metallic glass: Universal understanding of stress relaxation and creep

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