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

Feng, Shidong; Jiao, Wei; Qin, Jing; Qi, Li; Pan, Shaopeng; Li, G.; Z., M.; Wang, W. H.; Liu, R. P.

doi:10.1038/srep36627

Cited by 23 publications

(3 citation statements)

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“…Above the critical size, the increase in correlation length decreases the number of soft clusters, limiting strain percolation paths to form shear bands, intensifying the extent of strain localization and reducing the ductility of MGs. Since the population of soft spots and their spatial distribution can be tuned by such processes as rapid quenching, 14 high-pressure torsion, [55][56][57] laser processing, 58 and mechanical cycling, 59 and magnetization, 60 we envision that our results may offer a totally new approach of using the control of short-range to medium-range order in monolithic MGs to radically improve the ductility, and hence the fracture toughness, of these alloys. As such, this may provide new possibilities for the industrial application of these high-strength metallic alloys as structural materials with unique combinations of mechanical properties.…”

Section: A Transition In Shear-band Formation Mechanismsmentioning

confidence: 98%

Spatial correlation of elastic heterogeneity tunes the deformation behavior of metallic glasses

et al. 2018

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Metallic glasses (MGs) possess remarkably high strength but often display only minimal tensile ductility due to the formation of catastrophic shear bands. Purposely enhancing the inherent heterogeneity to promote distributed flow offers new possibilities in improving the ductility of monolithic MGs. Here, we report the effect of the spatial heterogeneity of elasticity, resulting from the inherently inhomogeneous amorphous structures, on the deformation behavior of MGs, specifically focusing on the ductility using multiscale modeling methods. A highly heterogeneous, Gaussian-type shear modulus distribution at the nanoscale is revealed by atomistic simulations in Cu 64 Zr 36 MGs, in which the soft population of the distribution exhibits a marked propensity to undergo the inelastic shear transformation. By employing a mesoscale shear transformation zone dynamics model, we find that the organization of such nanometer-scale shear transformation events into shear-band patterns is dependent on the spatial heterogeneity of the local shear moduli. A critical spatial correlation length of elastic heterogeneity is identified for the simulated MGs to achieve the best tensile ductility, which is associated with a transition of shear-band formation mechanisms, from stress-dictated nucleation and growth to structure-dictated strain percolation, as well as a saturation of elastically soft sites participating in the plastic flow. This discovery is important for the fundamental understanding of the role of spatial heterogeneity in influencing the deformation behavior of MGs. We believe that this can facilitate the design and development of new ductile monolithic MGs by a process of tuning the inherent heterogeneity to achieve enhanced ductility in these high-strength metallic alloys.

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Section: A Transition In Shear-band Formation Mechanismsmentioning

confidence: 98%

Spatial correlation of elastic heterogeneity tunes the deformation behavior of metallic glasses

et al. 2018

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“…It has been suggested that the so-called local atomic shear strain, η i Mises [56], denotes the atomic motions in local regions under stress and is related to the density of shear transformations [57,58]. Meanwhile, the atomic motions probably affect the distribution of free volumes.…”

Section: Resultsmentioning

confidence: 99%

Inhomogeneity of Free Volumes in Metallic Glasses under Tension

Wei

Wang

et al. 2018

Materials

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In this work, the deformation of Zr2Cu metallic glass (MG) under uniaxial tensile stress was investigated at the atomic level using a series of synchrotron radiation techniques combined with molecular dynamics simulation. A new approach to the quantitative detection of free volumes in MGs was designed and it was found that free volumes increase in the elastic stage, slowly expand in the yield stage, and finally reach saturation in the plastic stage. In addition, in different regions of the MG model, free volumes exhibited inhomogeneity under stress, in terms of size, density, and distribution. In particular, the expansion of free volumes in the center region was much more rapid than those in the other regions. It is interesting that the density of free volumes in the center region abnormally decreased with strain. It was revealed that the atomic-level stress between different regions may contribute to the inhomogeneity of free volumes under stress. In addition, the inhomogeneous change of free volumes during the deformation was confirmed by the evolution of local atomic shear strains in different regions. The present work provides in-depth insight into the deformation mechanisms of MGs.

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“…The hydrostatic stress during the HPT process rejuvenates the glassy structure by increasing the free volume. At the same time the amount of local ordering and the fraction of favored five-fold motifs 24,25 is increases and is stabilized by the hydrostatic stress 5 . This effect is not present in the sample stored at room temperature after HPT.…”

Section: A Structural Characteristicsmentioning

confidence: 99%

Structure-dynamics relationships in cryogenically deformed bulk metallic glass

Spieckermann,

Şopu,

Soprunyuk

et al. 2021

Preprint

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

Cited by 23 publications

References 50 publications

Spatial correlation of elastic heterogeneity tunes the deformation behavior of metallic glasses

Spatial correlation of elastic heterogeneity tunes the deformation behavior of metallic glasses

Inhomogeneity of Free Volumes in Metallic Glasses under Tension

Structure-dynamics relationships in cryogenically deformed bulk metallic glass

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