Networked interpenetrating connections of icosahedra: Effects on shear transformations in metallic glass

Lee, Mirim; Lee, Chang Myeon; Lee, Kwang Ryeol; Ma, Evan; Lee, Jae Chul

doi:10.1016/j.actamat.2010.09.020

Cited by 232 publications

(150 citation statements)

References 47 publications

Supporting

Mentioning

136

Contrasting

Unclassified

Order By: Relevance

“…Most of the structure models for the MRO in MG so far are derived from MD simulations. For example, MRO in Cu-Zr MDs has been proposed to be a string-like network of interpenetrating ICOs [20,25]. However, such a MRO picture is questionable due to the ultrahigh cooling rates in the MD simulations (~10 10 K/s or higher) compare to experimental cooling rates (usually on the order of 10 3 to 10 6 K/s).…”

Section: Introductionmentioning

confidence: 94%

“…The MRO in Cu-Zr MGs has been commonly characterized by the various types of connections among ICO [20]. If two ICO centers are not nearest neighbors of each other, but they share one, two or three common neighbor atoms, the types of connections are called vertex-, edge-or face-sharing, respectively.…”

Section: Evolution Of Isro and Mromentioning

confidence: 99%

“…Many molecular dynamics (MD) simulations have revealed the close relationships (1) between ISRO and glass forming ability [11] and transport properties [13,14] in supercooled Cu-Zr liquids and (2) between ISRO and mechanical properties [15][16][17] in Cu-Zr MGs. Meanwhile, the MRO in Cu-Zr MGs has also been intensively investigated, where the population of interpenetrating, vertex-, edge-and face-sharing ICO has been analyzed [18][19][20]. The interpenetrating ICO has been identified as a major type MRO in Cu-Zr MGs [19].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cooling rates dependence of medium-range order development inCu64.5Zr35.
Zhang
¹
,
Zhang
²
,
Wang
³

et al. 2015
Phys. Rev. B
55
6
31
0
View full text Add to dashboard Cite

The atomic structure of metallic glasses (MGs) plays an important role on their properties. Numerous molecular dynamics (MD) simulations have revealed the icosahedral short range order (ISRO) as a dominant motif in Cu-Zr metallic glasses.However, the cooling rates utilized in most of the MD simulations (usually on the order of 10 10-13 K/s) can be too high to allow the structure to relax into the actual structures. By performing a long sub-T g annealing of the Cu 64.5 Zr 35.5 alloy model at 700 K up to 2.0 μs using MD simulations, we systematically address the evolution of medium range order (MRO) as the cooling rates in MD simulations approach the experimental cooling rates (usually 10 3-6 K/s). By reducing the effective cooling rates to as low as 2.8×10 7 K/s, we found a significant enhancement of the ISRO and Bergman-type MRO. Comparing to the widely used face-, edge-or vertex-sharing icosahedra, we propose that the Bergman-type MRO is a much more unambiguous metric to characterize the MRO in Cu-Zr MGs. By analyzing the network formed by interpenetrating icosahedra using the graphical theory, we show that the degree of interpenetration of the icosahedra centers increases with decreasing cooling rates. The network becomes aggressively assortative, indicating that higher degree nodes tend to cluster and form backbones in the MG. All these results show that the networks in the models prepared using lower cooling rates strongly deviate from a string-like morphology. PACS number(s): 61.43. Dq, 61.43.Bn

show abstract

Section: Introductionmentioning

confidence: 94%

Section: Evolution Of Isro and Mromentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cooling rates dependence of medium-range order development inCu64.5Zr35.
Zhang
¹
,
Zhang
²
,
Wang
³

et al. 2015
Phys. Rev. B
55
6
31
0
View full text Add to dashboard Cite

show abstract

“…More recent work on colloidal glass systems with one particle size also revealed the details of the deformation dynamics, but only one type of transformation site was observed to be active (18). Besides the analog simulations, there have been a number of computational approaches to simulate glass structure and deformation response (19,20). Whereas those studies have offered insight into the details of the atom rearrangement under an imposed shear stress for specific interatomic potentials, the system sizes are small and the strain rates are exceedingly high so that the direct application of the findings to actual experimental conditions is somewhat unclear.…”

mentioning

confidence: 99%

Nucleation of shear bands in amorphous alloys

Perepezko

Imhoff

Chen

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

110

View full text Add to dashboard Cite

The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load-depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, T g . The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys.plastic deformation | stochastic analysis D eformation by shear bands occurs in both crystalline and amorphous phases over a wide range of size scales. In geological materials with a granular nature such as sand (1, 2) or within rocks, shear bands are of macroscopic size (3); in polymers and crystalline metals, shear bands are several micrometers in size; in metallic glasses (MGs), shear bands are of the order of 10-20 nm in thickness (4). The onset of shear bands in metallic glasses represents initial plastic yielding and induces a highly localized plastic flow that limits ductility and is responsible for strain softening (4, 5). Because shear bands directly determine the capability of an amorphous phase to sustain plastic flow and exhibit ductile behavior, there have been numerous studies on the propagation of shear bands to promote shear band branching and additional nucleation to achieve useful ductility (6-9). On a microscopic scale, the initiation of shear bands in MGs is considered to be controlled by the activation of a shear transformation zone (STZ) (10, 11) that represents a localized atomic arrangement. The STZs are activated by a two-stage process starting with a flow-induced dilatation that broadens homogeneously in the initial stage, but subsequently narrows into a shear band autocatalytically at the expense of shear flow in the surrounding material (10, 12). The localization of plastic flow would become predominant at low temperatures because the diffusive atomic rearrangements are too slow to disperse the dilatation effect quickly enough. Clearly, the nucleation of shear bands is of critical importance in the deformation behavior, but the detailed examination of the nucleation kinetics behavior has received only limited s...

show abstract

“…In a model Mg-Ca binary liquid, a majority of the local packing with five-fold symmetry was also reported with cooling [8]. More dramatic presence of the icosahedral packing has been reported recently in some of the bulk metallic glass systems, most noticeably those made of Zr and Cu [9][10][11][12][13]. The finding leads to the impression that the good glass-forming liquids are those with the excessive amount of locally ordered icosahedral packing or clusters with lower configuration energy.…”

mentioning

confidence: 91%

Rethinking atomic packing and cluster formation in metallic liquids and glasses

2011

Chin. Sci. Bull.

View full text Add to dashboard Cite

In traditional view, atomic packing is random in glasses made of metallic elements with non-directional interactions as the glass-forming liquid needs to be excited to remain in liquid state before being cooled sufficiently fast to a glass. Locally ordered packing however is possible if certain conditions are favorable, such as a strong bonding between elements, or low configuration energy of a cluster of atoms as suggested by Frank. In alloy systems made of different metallic elements, we show that Frank's criterion alone does not necessarily lead to certain specific local ordered packing or cluster formation such as icosahedral packing. In this context, we revisit the issue of atomic packing and cluster formation, and show that an alloy system with fairly random liquid configuration could be sufficient to produce a variety of noticeable locally ordered packing with low energy, albeit largely statistical in nature. Therefore, we emphasize the importance of the system parameters such as the atomic size, alloy concentration, and interaction potential in their collective contribution to local atomic packing. The question of whether or not a liquid should have a locally ordered structure has a significant bearing on many issues in materials science and condensed matter physics. To some extent, stability of a liquid depends on whether or not such an ordered structure exists, so deep undercooling could be achieved [1]. A glass-forming liquid with extended stability is a precursor for good glass forming ability as the cooling rate q = T/t is determined by the temperature gap T= T l T g between the liquidus line T l and the glass transition temperature T g , and   t which is the time taken during cooling across the gap. A critical cooling rate is represented by the slowest q for a system. Obviously, a system with the smallest T would have the slowest cooling rate at a sufficiently long cooling time to avoid crystallization, thus more stable [2]. When local atomic packing with certain noncrystalline order is present, the liquid would have lower configuration energy and therefore a low T l . So the liquid becomes more stable and could be made relatively easily into a glass [1,2]. One such locally ordered packing is icosahedral cluster made of 13 atoms. As proposed by Frank [1], by considering the pairwise interactomic interactions, i.e. the LennardJones (LJ) interaction,  LJ (r), between atoms separated by a distance r, the potential energy of the central atom interacting with the 12 nearest neighbor atoms would be about 8.4% lower if they are packed as an icosahedron than that if they are packed as the face-centered-cubic (fcc) structure. An icosahedron packing requires that all 12 neighboring atoms are located at the vertex points of 3 perpendicular rectangles with the golden ratio. In contrast, an fcc packing has all 12 neighboring atoms sitting at the vertices of 3 perpendicular squares. As a result, the ratio between the nearest neighbor distances in an icosahedron is shorter than that in an fcc by

show abstract

Networked interpenetrating connections of icosahedra: Effects on shear transformations in metallic glass

Cited by 232 publications

References 47 publications

Cooling rates dependence of medium-range order development inCu64.5Zr35.
Zhang
¹
,
Zhang
²
,
Wang
³

et al. 2015
Phys. Rev. B
55
6
31
0
View full text Add to dashboard Cite

Cooling rates dependence of medium-range order development inCu64.5Zr35.
Zhang
¹
,
Zhang
²
,
Wang
³

et al. 2015
Phys. Rev. B
55
6
31
0
View full text Add to dashboard Cite

Nucleation of shear bands in amorphous alloys

Rethinking atomic packing and cluster formation in metallic liquids and glasses

Contact Info

Product

Resources

About

Networked interpenetrating connections of icosahedra: Effects on shear transformations in metallic glass

Cited by 232 publications

References 47 publications

Cooling rates dependence of medium-range order development inCu64.5Zr35.Zhang1, Zhang2, Wang3 et al. 2015Phys. Rev. B556310View full textAdd to dashboardCite

Cooling rates dependence of medium-range order development inCu64.5Zr35.Zhang1, Zhang2, Wang3 et al. 2015Phys. Rev. B556310View full textAdd to dashboardCite

Nucleation of shear bands in amorphous alloys

Rethinking atomic packing and cluster formation in metallic liquids and glasses

Contact Info

Product

Resources

About

Cooling rates dependence of medium-range order development inCu64.5Zr35.
Zhang
¹
,
Zhang
²
,
Wang
³

et al. 2015
Phys. Rev. B
55
6
31
0
View full text Add to dashboard Cite

Cooling rates dependence of medium-range order development inCu64.5Zr35.
Zhang
¹
,
Zhang
²
,
Wang
³

et al. 2015
Phys. Rev. B
55
6
31
0
View full text Add to dashboard Cite