Shear Bands in Monolithic Metallic Glasses: Experiment, Theory, and Modeling

Hubek, René; Hilke, Sven; Davani, Farnaz A.; Golkia, Mehrdad; Shrivastav, Gaurav P.; Divinski, Sergiy V.; Rösner, Harald; Horbach, Jürgen; Wilde, Gerhard

doi:10.3389/fmats.2020.00144

Cited by 11 publications

(4 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Plastic deformation of bulk metallic glasses (BMGs) at room temperature occurs through the generation of highly localized shear bands propagating at the microscale in an approximately straight manner [1,2] (although shear band deflections have been observed at the nanoscale [3,4]). Recent molecular-dynamics simulations [5] indicate that this behavior results from the sequential activation of shear transformation zones (STZs, the elementary units of plasticity in BMGs [6,7]) along a specific direction.…”

Section: Introductionmentioning

confidence: 99%

Guiding shear bands in bulk metallic glasses using stress fields: A perspective from the activation of flow units

et al. 2020

View full text Add to dashboard Cite

Controlling shear band propagation is the key to obtain ductile metallic glasses. Here, we use a residual stress field to vary the direction of shear band propagation. We ascribe this behavior to the effect of the stress field on the activation of shear transformation zones (STZs) along their characteristic direction and we quantify this contribution to the energy of the process. Because of the progressively adverse orientation of the stress field, the energy stored as shear in the STZ decreases to a level where shear band propagation at alternative angles becomes energetically more favorable.

show abstract

Section: Introductionmentioning

confidence: 99%

Guiding shear bands in bulk metallic glasses using stress fields: A perspective from the activation of flow units

et al. 2020

View full text Add to dashboard Cite

show abstract

“…For brevity, these results are not included here but they confirmed the results of the compression tests [10,43,46]. More comprehensive details of the sample processing and deformation are given in reference [10,47]. Electron-transparent samples were prepared by electropolishing with a BK-2 electrolyte [48] at 16.5 V / −20 • C using a Tenupol 5 electropolishing device (Struers A/S, Denmark).…”

mentioning

confidence: 85%

The role of minor alloying in the plasticity of bulk metallic glasses

Hilke,

Rösner,

Wilde

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Micro-or minor alloying of metallic glasses is of technological interest. An originally ductile Pd-based monolithic bulk metallic glass (Pd 40 Ni 40 P 20 ) was selectively manipulated by additions of Fe or Co. The alloying effects were extreme, showing either exceptional ductility upon Co addition or immediate catastrophic failure upon Fe addition when tested under uniaxial compression or 3-point bending. The amorphous structure was characterized prior to deformation with respect to its medium-range order (MRO) using variable resolution fluctuation electron microscopy (VR-FEM). We observe striking differences in the MRO between the ductile and brittle metallic glasses, with the ductile glasses exhibiting a rich structural diversity and MRO correlation lengths up to 6 nm. The MRO heterogeneity seems to enable easier shear banding and hence enhance the deformability.

show abstract

“…Shear banding is a ubiquitous phenomenon in glasses under mechanical load [14,15,. Especially in metallic glasses, shear bands lead to inhomogeneities in the microstructure and can cause a catastrophic failure of the material [14,22,25]. In aqs simulations of a glassforming binary Lennard-Jones mixture, Parmar et al [39] have demonstrated that shearbanded states can be stabilized by applying oscillatory shear with an appropriate strain amplitude, thereby obtaining states where a fluidized band coexists with a stress-released amorphous solid.…”

Section: Introductionmentioning

confidence: 99%

Brittle yielding in supercooled liquids below the critical temperature of mode coupling theory

Lamp,

Küchler,

Horbach

2022

Preprint

Self Cite

View full text Add to dashboard Cite

Molecular Dynamics (MD) computer simulations of a polydisperse soft-sphere model under shear are presented. Starting point for these simulations are deeply supercooled samples far below the critical temperature, Tc, of mode coupling theory. These samples are fully equilibrated with the aid of the swap Monte Carlo technique. For states below Tc, we identify a life time τ lt that measures the time scale on which the system can be considered as an amorphous solid. The temperature dependence of τ lt can be well described by an Arrhenius law. The existence of transient amorphous solid states below Tc is associated with the possibility of brittle yielding, as manifested by a sharp stress drop in the stress-strain relation and shear banding. We show that brittle yielding requires on the one hand low shear rates and on the other hand, the time scale corresponding to the inverse shear rate has to be smaller or of the order of τ lt . Both conditions can be only met for large life time τ lt , i.e. for states far below Tc.

show abstract

Shear Bands in Monolithic Metallic Glasses: Experiment, Theory, and Modeling

Cited by 11 publications

References 57 publications

Guiding shear bands in bulk metallic glasses using stress fields: A perspective from the activation of flow units

Guiding shear bands in bulk metallic glasses using stress fields: A perspective from the activation of flow units

The role of minor alloying in the plasticity of bulk metallic glasses

Brittle yielding in supercooled liquids below the critical temperature of mode coupling theory

Contact Info

Product

Resources

About