Diffusion in a Cu-Zr metallic glass studied by microsecond-scale molecular dynamics simulations

Zhang, Y.; Wang, C. Z.; Mendelev, Mikhail I.; Zhang, F.; Kramer, M. J.; Ho, Kai‐Ming

doi:10.1103/physrevb.91.180201

Cited by 35 publications

(29 citation statements)

References 38 publications

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“…While the structure-dynamics features of icosahedron networks are becoming well-documented for temperatures near T g [32,33,47], the roles played by these structures at higher temperatures have remained largely unknown. Thus, our findings stand amongst the first explicit accounts of the structural features that accompany the emergence of solid-like features in high-temperature metallics liquids.…”

Section: T a And Cooperative Structural Rearrangementsmentioning

confidence: 99%

“…In particular, Zhang et al recently showed quite explicitly that diffusing atoms strongly avoid regions of icosahedral ordering, and that they instead reside in liquid-like regions of the system [47]. They demonstrate that underlying the development of medium-ranged icosahedral ordering and glassy dynamics is a crucial correspondence between dynamical and structural correlation length scales in the liquid.…”

Section: As the Liquid Is Supercooled Through T D Its Relaxation Timentioning

confidence: 99%

“…There are numerous studies that demonstrate the unique role played by icosahedron FLDs in creating strong dynamical heterogeneities in Cu 64 Zr 36 as it is supercooled towards T g [32,33,47]. In particular, Zhang et al recently showed quite explicitly that diffusing atoms strongly avoid regions of icosahedral ordering, and that they instead reside in liquid-like regions of the system [47].…”

Section: As the Liquid Is Supercooled Through T D Its Relaxation Timentioning

confidence: 99%

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A locally preferred structure characterises all dynamical regimes of a supercooled liquid

Soklaski

Tran

Nussinov

et al. 2016

Philosophical Magazine

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A locally preferred structure characterises all dynamical regimes of a supercooled liquid, Philosophical Magazine, 96:12, 1212-1227, DOI: 10.1080/14786435.2016 ABSTRACTRecent experimental results suggest that metallic liquids universally exhibit a high-temperature dynamical crossover, which is correlated with the glass transition temperature (T g ). We demonstrate, using molecular dynamics results for Cu 64 Zr 36 , that this temperature, T A ≈ 2 × T g , is linked with cooperative atomic rearrangements that produce domains of connected icosahedra. Supercooling to a new characteristic temperature, T D , is shown to produce higher order cooperative rearrangements amongst connected icosahedra, which manifests as the formation of large Zr-rich connected domains that possess macroscopic proportions of the liquid's icosahedra. This coincides with the decoupling of atomic diffusivities, largescale domain fluctuations and the onset of glassy dynamics in the liquid. These extensive domains then abruptly stabilise above T g and eventually percolate before the glass is formed. All characteristic temperatures (T A , T D and T g ) are thus connected by successive manifestations of the structural cooperativity that begins at T A . ARTICLE HISTORY

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Section: T a And Cooperative Structural Rearrangementsmentioning

confidence: 99%

Section: As the Liquid Is Supercooled Through T D Its Relaxation Timentioning

confidence: 99%

Section: As the Liquid Is Supercooled Through T D Its Relaxation Timentioning

confidence: 99%

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A locally preferred structure characterises all dynamical regimes of a supercooled liquid

Soklaski

Tran

Nussinov

et al. 2016

Philosophical Magazine

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“…Specifically, the type of characteristic SRO varies from alloy to alloy and is not universal for metallic glass-forming liquids. 30,31,[63][64][65][66][67][68][69] The metric based on peak intensity in structure factors or PDFs shows considerable fluctuation when correlated with liquid fragility, 28,29,71 and the peak height may involve other effects, such as thermally enhanced asymmetry of peaks in the PDF, as will be discussed in a later section. More importantly, all these indicators do not necessarily reveal a causal link with the dynamical slowdown at the microscopic level.…”

Section: Introductionmentioning

confidence: 99%

Computational modeling sheds light on structural evolution in metallic glasses and supercooled liquids

Ding

2017

npj Comput Mater

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This article presents an overview of three challenging issues that are currently being debated in the community researching on the evolution of amorphous structures in metallic glasses and their parent supercooled liquids. Our emphasis is on the valuable insights acquired in recent computational analyses that have supplemented experimental investigations. The first idea is to use the local structural order developed, and in particular its evolution during undercooling, as a signature indicator to rationalize the experimentally observed temperature-dependence of viscosity, hence suggesting a possible structural origin of liquid fragility. The second issue concerns with the claim that the average nearest-neighbor distance in metallic melts contracts rather than expands upon heating, concurrent with a reduced coordination number. This postulate is, however, based on the shift of the first peak maximum in the pair distribution function and an average bond length determined from nearest neighbors designated using a distance cutoff. These can instead be a result of increasing skewness of the broad first peak, upon thermally exacerbated asymmetric distribution of neighboring atoms activated to shorter and longer distances under the anharmonic interatomic interaction potential. The third topic deals with crystal-like peak positions in the pair distribution function of metallic glasses. These peak locations can be explained using various connection schemes of coordination polyhedra, and found to be present already in high-temperature liquids without hidden crystal order. We also present an outlook to invite more in-depth computational research to fully settle these issues in future, and to establish more robust structure-property relations in amorphous alloys.npj Computational Materials (2017) 3:9 ;

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“…It has been shown that icosahedral clusters tend to connect each other under cooling and form percolating network as the system approaches glass transition 10,12 . Besides, the correlation between icosahedral ordering and glassy dynamics has arXiv:1604.07024v1 [cond-mat.dis-nn] 24 Apr 2016 been ascertained 13,17 . Despite of wide acceptance of the icosahedral order, alternative clusters have been considered to be important structural elements in Cu-Zr metallic glasses 10,11,[18][19][20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure

Ryltsev

Klumov

Chtchelkatchev

et al. 2016

The Journal of Chemical Physics

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Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 · 10 9 , 10 13 ) K/s. Investigating short-and medium-range order, we show that structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to a increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γmin = 1.5 · 10 9 K/s. Analysing the structure of the glass at γmin, we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two type of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds and explains the drastic increase of the abundances of these clusters observed at γmin.

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Diffusion in a Cu-Zr metallic glass studied by microsecond-scale molecular dynamics simulations

Cited by 35 publications

References 38 publications

A locally preferred structure characterises all dynamical regimes of a supercooled liquid

A locally preferred structure characterises all dynamical regimes of a supercooled liquid

Computational modeling sheds light on structural evolution in metallic glasses and supercooled liquids

Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure

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