Local atomic environment and shear banding in metallic glasses

Tercini, Marcela; Veiga, Rga; Zúñiga, Alejandro

doi:10.1016/j.commatsci.2018.08.025

Cited by 8 publications

(4 citation statements)

References 32 publications

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“…It has long been recognized that localized plastic events in deformed amorphous materials involve collective rearrangements of small clusters of atoms, or shear transformations [5,6]. In recent years, the processes of shear band initiation and propagation have been extensively studied at the atomic level during startup uniaxial [7][8][9][10][11] and shear [12][13][14] deformation with a constant strain rate. While the initiation of a shear band typically occurs at a free surface during tension or compression, the transition to plastic flow in a sheared periodic domain involves the formation of a percolating cluster of mobile regions at the critical strain [12].…”

Section: Introductionmentioning

confidence: 99%

Shear Band Formation in Amorphous Materials under Oscillatory Shear Deformation

Priezjev

2020

Metals

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The effect of periodic shear on strain localization in disordered solids is investigated using molecular dynamics simulations. We consider a binary mixture of one million atoms annealed to a low temperature with different cooling rates and then subjected to oscillatory shear deformation with a strain amplitude slightly above the critical value. It is found that the yielding transition occurs during one cycle but the accumulation of irreversible displacements and initiation of the shear band proceed over larger number of cycles for more slowly annealed glasses. The spatial distribution and correlation function of nonaffine displacements reveal that their collective dynamics changes from homogeneously distributed small clusters to a system-spanning shear band. The analysis of spatially averaged profiles of nonaffine displacements indicates that the location of a shear band in periodically loaded glasses can be identified at least several cycles before yielding. These insights are important for development of novel processing methods and prediction of the fatigue lifetime of metallic glasses.

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Section: Introductionmentioning

confidence: 99%

Shear Band Formation in Amorphous Materials under Oscillatory Shear Deformation

Priezjev

2020

Metals

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“…The value q 6 = 0.663 represents a perfect icosahedron [39,40]. The Cu-centered icosahedra in the shear band are severely destroyed and some other polyhedra are formed, whose first nearest neighbors are characterized by q 6 < 0.57 [41]. Kim and Ryu found that Cu atoms with higher q 6 have higher structural rigidity and are more resistant to deformation [42].…”

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Simulation of Structural Signals of Shear-Band Formation in Zr46Cu46Al8 Metallic Glasses

et al. 2018

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The evolution from initiation to formation of a shear band in Zr46Cu46Al8 metallic glasses is presented via molecular dynamics simulation. The increase in number and the decrease in average size of clusters with the quasi-nearest atoms being 0 correspond to the shear-band evolution from initiation to formation. When the shear band is completely formed, the distribution of the bond orientational order q6 reaches a minimum. The maximum of the number of the polyhedral loss of Cu-centered <0, 0, 12, 0> and the minimum of the number of the polyhedral loss of Zr-centered <0, 2, 8, 5> correspond to the shear-band formation. These findings provide a strong foundation for characterizing the evolution from initiation to formation of shear bands.

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“…Finally, the local five-fold symmetry has been linked in previous works, to the microscopic beahavior at the glass transition [29,30] and within SBs [9]. In order to clarify the local structure of the shear band, we will focus our attention on the traced atoms and, as an indication of the local structure, we will calculate the local five-fold symmetry, L5FS, for those atoms.…”

Section: Global Analysismentioning

confidence: 99%

“…Among the many existing MGs, one that has been the object of many studies, both experimental and numerical, is CuZr, with a variety of relative Cu contents, and with the possible addition of other elements such as Al [16,17]. This interest stems from their superior glass forming ability [18], sensitivity of mechanical behavior to composition [19], and the existence of reliable interatomic potentials for numerical simulations [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Precursors to plastic failure in a numerical simulation of CuZr metallic glass

Sepúlveda-Macías

Gutiérrez²,

Lund³

2020

J. Phys.: Condens. Matter

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We deform, in pure shear, a thin sample of Cu50Zr50 metallic glass using a molecular dynamics simulation up to, and including, failure. The experiment is repeated ten times in order to have average values and standard deviations. Although failure occurs at the same value of the externally imposed strain for the ten samples, there is significant sample-to-sample variation in the specific microscopic material behavior. Failure can occur along one, two, or three planes, located at the boundaries of previously formed shear bands. These shear bands form shortly before failure.However, well before their formation and at external strains where plastic deformation just begins to be significant, non-affine displacement organizes itself along localized bands. The shear bands subsequently form at the edges of these non-affinedisplacement-bands, and present an alternating rotation-quadrupole structure, as found previously by Şopu et al. [1] in the case of a notched sample loaded in tension.The thickness of shear bands is roughly determined by the available plastic energy.The onset of shear banding is accompanied by a sharp increase in the rate of change of the rotation angle localization, the strain localization, and the non-affine square displacement.

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Local atomic environment and shear banding in metallic glasses

Cited by 8 publications

References 32 publications

Shear Band Formation in Amorphous Materials under Oscillatory Shear Deformation

Shear Band Formation in Amorphous Materials under Oscillatory Shear Deformation

Molecular Dynamics Simulation of Structural Signals of Shear-Band Formation in Zr46Cu46Al8 Metallic Glasses

Precursors to plastic failure in a numerical simulation of CuZr metallic glass

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