Deformation of metallic glasses: Recent developments in theory, simulations, and experiments

Hufnagel, T. C.; Schuh, Christopher A.; Falk, Michael L.

doi:10.1016/j.actamat.2016.01.049

Cited by 461 publications

(188 citation statements)

References 227 publications

(221 reference statements)

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“…Differences in the cooling rate of metallic glasses upon casting from the melt result in different final energy states of the amorphous solid 6 . Higher cooling rates allow freezing of the metallic glass at a higher potential energy level 1 , and it was established that metallic glasses on higher energy state have a higher plasticity 5 . Ribbon samples can be bent by 180°without fracture 7 .…”

Section: Introductionmentioning

confidence: 99%

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On cryothermal cycling as a method for inducing structural changes in metallic glasses

et al. 2018

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The influence of cryothermal treatment on the mechanical properties of metallic glasses with different compositions was investigated in the present work. It was found that cryothermal cycling can induce rejuvenation as well as relaxation of the metallic glasses. The local apparent Young's modulus and its spatial distribution width on the surface of the metallic glass increase after cryothermal cycling, while in the bulk the effect depends on the glass composition. It appeared that this increase is temporary and disappears after a period of room temperature aging. This effect is connected with a large distribution of relaxation times in the metallic glasses due to their heterogeneous structure and the formation of complex native oxides on the outer surfaces of the glasses. Our findings reveal that a cryothermal cycling treatment can improve or degrade the plasticity of a metallic glass, and the atomic bond structure appears to be very important for the outcome of the treatment.

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Section: Introductionmentioning

confidence: 99%

“…However, the lack of macroscopic ductility limits their application fields 4,5 . Differences in the cooling rate of metallic glasses upon casting from the melt result in different final energy states of the amorphous solid 6 .…”

Section: Introductionmentioning

confidence: 99%

On cryothermal cycling as a method for inducing structural changes in metallic glasses

et al. 2018

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“…Metallic glass Nanoindentation Strain rate Indentation size effect Metallic glasses have been long regarded as potential structural materials due to their ultra-high strength and hardness [1,2]. Therefore, a number of researchers have paid much attention to the factors that will influence the hardness of metallic glass [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Testing effects on hardness of a Zr-based metallic glass under nanoindentation

Jiang

et al. 2017

Scripta Materialia

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A series of nanoindentation tests were performed on a Zr-based bulk metallic glass at different peak-loads and strain rates. It is observed that the strain rate sensitivity index gradually decreases from positive to almost zero with increasing peak-load. Furthermore, at a fixed strain rate, the indentation hardness firstly shows a dramatic reduction and then becomes stable with increasing peak-load. These observations can be well understood in the framework of the activation and the accumulation of free volume via shear transformation zones. The current work may provide a practical way to tailor the hardness of the metallic glass.© 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords:Metallic glass Nanoindentation Strain rate Indentation size effect Metallic glasses have been long regarded as potential structural materials due to their ultra-high strength and hardness [1,2]. Therefore, a number of researchers have paid much attention to the factors that will influence the hardness of metallic glass [3][4][5]. For instance, it is demonstrated that the increase of loading rate corresponded to a decrease of hardness and the underlying mechanism was attributed to the free volume relaxation induced hardening that was more dramatic under lower strain rates [6]. However, the free volume dynamics includes not only the relaxation induced annihilation, but also stress driven creation [7][8][9]. It is believed that the free volume creation could lead to a softening effect on the hardness of metallic glasses [10,11]. Therefore, both hardening and softening effects of strain rates on the hardness is possible. For example, Xue et al. [12] reported a positive strain rate dependence of the hardness and ascribed this correlation to the stronger strain rate softening effect under lower strain rates. There are also analogous inconsistent results, but the underlying mechanism has been rarely shed light on [13][14][15][16][17]. In addition, Bhattacharyya et al. [6] demonstrated a lower strain rate sensitivity of the hardness under a higher peak-load, but the results of Ma et al. [17,18] showed a much more positive rate sensitivity when the peak-load increased by 1 order of magnitude. Moreover, Jang et al. [19] reported a continuous reduction of hardness with increasing peak-load or indentation size, i.e., an indentation size effect (ISE). On the contrary, Wang et al. [20] recently demonstrated that the ISE would disappear when the indentation size is larger than a critical value.Evidently, the dependence of hardness on the testing conditions (strain rate and peak-load) under nanoindentation is still under debate. Further exploration is required to gain more insights into these issues. In the current work, a series of nanoindentation tests were performed on a Zr-based metallic glass under different peak-loads and strain rates. A positive dependence of hardness on the strain rate is found. Meanwhile, both the strain rate sensitivity index and the indentation hardness firstly decrease and then become stabl...

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“…Bulk metallic glasses (BMGs) are amorphous solids that are well known for their excellent mechanical properties, which render them attractive for many technological applications [1][2][3][4]. Although these materials are heavily investigated both experimentally and theoretically, the yielding and failure of BMGs under external strain are still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Magnetic small-angle neutron scattering on bulk metallic glasses: A feasibility study for imaging displacement fields

Mettus

Deckarm

Leibner

et al. 2017

Phys. Rev. Materials

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Magnetic-field-dependent small-angle neutron scattering (SANS) has been utilized to study the magnetic microstructure of bulk metallic glasses (BMGs). In particular, the magnetic scattering from soft magnetic Fe 70 Mo 5 Ni 5 P 12.5 B 2.5 C 5 and hard magnetic (Nd 60 Fe 30 Al 10 ) 92 Ni 8 alloys in the as-prepared, aged, and mechanically deformed state is compared. While the soft magnetic BMGs exhibit a large field-dependent SANS response with perturbations originating predominantly from spatially varying magnetic anisotropy fields, the SANS cross sections of the hard magnetic BMGs are only weakly dependent on the field, and their angular anisotropy indicates the presence of scattering contributions due to spatially dependent saturation magnetization. Moreover, we observe an unusual increase in the magnetization of the rare-earth-based alloy after deformation. Analysis of the SANS cross sections in terms of the correlation function of the spin misalignment reveals the existence of field-dependent anisotropic long-wavelength magnetization fluctuations on a scale of a few tens of nanometers. We also give a detailed account of how the SANS technique relates to unraveling displacement fields on a mesoscopic length scale in disordered magnetic materials.

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Deformation of metallic glasses: Recent developments in theory, simulations, and experiments

Cited by 461 publications

References 227 publications

On cryothermal cycling as a method for inducing structural changes in metallic glasses

On cryothermal cycling as a method for inducing structural changes in metallic glasses

Testing effects on hardness of a Zr-based metallic glass under nanoindentation

Magnetic small-angle neutron scattering on bulk metallic glasses: A feasibility study for imaging displacement fields

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