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Second-Nearest-Neighbor Correlations from Connection of Atomic Packing Motifs in Metallic Glasses and Liquids.

Ding J, Ma E, Asta M, Ritchie RO - Sci Rep (2015)

Bottom Line: The analysis was conducted from the perspective of different connection schemes of atomic packing motifs, based on the number of shared atoms between two linked coordination polyhedra.These properties of the connections and the resultant atomic correlations are generally the same for different types of packing motifs in different alloys.Increasing ordering and cluster connection during cooling, however, may tune the position and intensity of the split peaks.

View Article: PubMed Central - PubMed

Affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

ABSTRACT
Using molecular dynamics simulations, we have studied the atomic correlations characterizing the second peak in the radial distribution function (RDF) of metallic glasses and liquids. The analysis was conducted from the perspective of different connection schemes of atomic packing motifs, based on the number of shared atoms between two linked coordination polyhedra. The results demonstrate that the cluster connections by face-sharing, specifically with three common atoms, are most favored when transitioning from the liquid to glassy state, and exhibit the stiffest elastic response during shear deformation. These properties of the connections and the resultant atomic correlations are generally the same for different types of packing motifs in different alloys. Splitting of the second RDF peak was observed for the inherent structure of the equilibrium liquid, originating solely from cluster connections; this trait can then be inherited in the metallic glass formed via subsequent quenching of the parent liquid through the glass transition, in the absence of any additional type of local structural order. Increasing ordering and cluster connection during cooling, however, may tune the position and intensity of the split peaks.

No MeSH data available.


Related in: MedlinePlus

(a) Radial distribution functions g(r) of Ta liquids at 3300 K (orange line) and the inherent structures of Ta liquids at 3300 K (cyan line) as well Ta glass at 300 K (blue dashed line). The inset schematically illustrates the atomic order at the second nearest-neighbor shell as the correlation between two central atoms (as marked), which also corresponds to the second peak in g(r). (b) Shown schematically are four different schemes of coordination polyhedra connections with the number of shared atoms from one to four, which are denoted as 1-atom, 2-atom, 3-atom, and 4-atom cluster connections, respectively.
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f1: (a) Radial distribution functions g(r) of Ta liquids at 3300 K (orange line) and the inherent structures of Ta liquids at 3300 K (cyan line) as well Ta glass at 300 K (blue dashed line). The inset schematically illustrates the atomic order at the second nearest-neighbor shell as the correlation between two central atoms (as marked), which also corresponds to the second peak in g(r). (b) Shown schematically are four different schemes of coordination polyhedra connections with the number of shared atoms from one to four, which are denoted as 1-atom, 2-atom, 3-atom, and 4-atom cluster connections, respectively.

Mentions: To illustrate how the second-NN pair correlation distance is related to the cluster connection, Fig. 1(a) shows schematically two representative atoms that are second nearest neighbors. Each of these two atoms is of course the center of its own coordination polyhedron (cluster)313233343536. The two clusters are represented by the two color-shaded regions in Fig. 1(a). They are connected together, by the atoms at the locations where the two clusters overlap (the shared atoms). For any arbitrary reference atom, its second NN shell can be pictured as composed of atoms each at the center of a cluster connected to that of the reference atom (see the example depicted in the inset in Fig. 1(a)). For all the atoms in the second NN shell, their spatial correlations with the reference atom superimpose into the second peak in the RDF, g(r), as indicated in Fig. 1(a).


Second-Nearest-Neighbor Correlations from Connection of Atomic Packing Motifs in Metallic Glasses and Liquids.

Ding J, Ma E, Asta M, Ritchie RO - Sci Rep (2015)

(a) Radial distribution functions g(r) of Ta liquids at 3300 K (orange line) and the inherent structures of Ta liquids at 3300 K (cyan line) as well Ta glass at 300 K (blue dashed line). The inset schematically illustrates the atomic order at the second nearest-neighbor shell as the correlation between two central atoms (as marked), which also corresponds to the second peak in g(r). (b) Shown schematically are four different schemes of coordination polyhedra connections with the number of shared atoms from one to four, which are denoted as 1-atom, 2-atom, 3-atom, and 4-atom cluster connections, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663502&req=5

f1: (a) Radial distribution functions g(r) of Ta liquids at 3300 K (orange line) and the inherent structures of Ta liquids at 3300 K (cyan line) as well Ta glass at 300 K (blue dashed line). The inset schematically illustrates the atomic order at the second nearest-neighbor shell as the correlation between two central atoms (as marked), which also corresponds to the second peak in g(r). (b) Shown schematically are four different schemes of coordination polyhedra connections with the number of shared atoms from one to four, which are denoted as 1-atom, 2-atom, 3-atom, and 4-atom cluster connections, respectively.
Mentions: To illustrate how the second-NN pair correlation distance is related to the cluster connection, Fig. 1(a) shows schematically two representative atoms that are second nearest neighbors. Each of these two atoms is of course the center of its own coordination polyhedron (cluster)313233343536. The two clusters are represented by the two color-shaded regions in Fig. 1(a). They are connected together, by the atoms at the locations where the two clusters overlap (the shared atoms). For any arbitrary reference atom, its second NN shell can be pictured as composed of atoms each at the center of a cluster connected to that of the reference atom (see the example depicted in the inset in Fig. 1(a)). For all the atoms in the second NN shell, their spatial correlations with the reference atom superimpose into the second peak in the RDF, g(r), as indicated in Fig. 1(a).

Bottom Line: The analysis was conducted from the perspective of different connection schemes of atomic packing motifs, based on the number of shared atoms between two linked coordination polyhedra.These properties of the connections and the resultant atomic correlations are generally the same for different types of packing motifs in different alloys.Increasing ordering and cluster connection during cooling, however, may tune the position and intensity of the split peaks.

View Article: PubMed Central - PubMed

Affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

ABSTRACT
Using molecular dynamics simulations, we have studied the atomic correlations characterizing the second peak in the radial distribution function (RDF) of metallic glasses and liquids. The analysis was conducted from the perspective of different connection schemes of atomic packing motifs, based on the number of shared atoms between two linked coordination polyhedra. The results demonstrate that the cluster connections by face-sharing, specifically with three common atoms, are most favored when transitioning from the liquid to glassy state, and exhibit the stiffest elastic response during shear deformation. These properties of the connections and the resultant atomic correlations are generally the same for different types of packing motifs in different alloys. Splitting of the second RDF peak was observed for the inherent structure of the equilibrium liquid, originating solely from cluster connections; this trait can then be inherited in the metallic glass formed via subsequent quenching of the parent liquid through the glass transition, in the absence of any additional type of local structural order. Increasing ordering and cluster connection during cooling, however, may tune the position and intensity of the split peaks.

No MeSH data available.


Related in: MedlinePlus