Yielding and shear banding of metallic glasses

Liu, Z.Y.; Yang, Yong; Liu, C.T.

doi:10.1016/j.actamat.2013.06.025

Cited by 63 publications

(21 citation statements)

References 51 publications

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“…Consequently, in one shear event, the stress-strain behavior should be work-softening, although the overall trend for the discretely growth of shear band shows apparent hardening. The inherent softening nature of shear banding has been verified by many other experiments [2,8,13,77], and can be interpreted by the shearing-induced dilatation and temperature rise [9,26,78,79].…”

Section: Influence Of Multiple Shear Bandingmentioning

confidence: 82%

“…Schuh and Lund [68] found that the normal stress on the shear plane influences the shear resistance of STZ activations, which should be the physical origin for that the Mohr-Coulomb criterion [49,54,68] or the Ellipse criterion [50,64,69] rather than the maximum shear stress criterion can well explain the yield or fracture behavior of MGs. Once an STZ cluster reaches the critical state of nucleation, which may correspond to a critical excess free volume [7,21], or a critical viscosity [8], or equivalently other conditions [61,70,71], a shear band will be nucleated along the shear plane of the STZ cluster.…”

Section: Formation Of Shear Band and The First Shearmentioning

confidence: 99%

“…For instance, the critical stress for initiating a shear band determines the upper limit of yield stress, while the density of shear band and the critical failure condition of shear band control the global plasticity of MGs. However, the formation mechanism of shear band still remains unclear so far, although great strides have been made over the past decade in understanding the inherent mechanism of shear banding behavior in MGs (e.g., [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]). …”

Section: Introductionmentioning

confidence: 99%

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Progressive shear band propagation in metallic glasses under compression

et al. 2015

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Section: Influence Of Multiple Shear Bandingmentioning

confidence: 82%

Section: Formation Of Shear Band and The First Shearmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Progressive shear band propagation in metallic glasses under compression

et al. 2015

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“…It is widely accepted that shear transformation zone (STZ) is the embryo of localized shear event in BMGs at atomic-scale, and the yielding of BMGs corresponds to the unsteady propagation of a large number of STZs [29][30][31][32]. The cooperative shear model of STZs developed by Johnson and Samwer [30] gives an universal law for the shear yielding strength of BMGs as:…”

Section: Discussionmentioning

confidence: 99%

Effect of strain rate on yielding strength of a Zr-based bulk metallic glass

Jiang

Yang

et al. 2017

Materials Science and Engineering: A

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A B S T R A C TUniaxial tension and compression experiments were performed on a typical Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 (Vit 105) bulk metallic glass over a wide range of strain rates at room temperature. It is found that the strain rate effect of the yielding strength will change from insensitive to negative with increasing strain rate above a critical value. This phenomenon can be quantitatively described by a modified cooperative-shear model of shear transformation zones that takes the adiabatic temperature rise into account. The model predicts well the present and other experimental data.

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“…It leads to the formation of one mature shear band. Then the elastic backbone will be penetrated and give rise to irreversible macroscopic yield of the metallic glass [20,27,28]. The critical stress corresponds to the yield strength or the hardness.…”

Section: Contents Lists Available At Sciencedirectmentioning

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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Yielding and shear banding of metallic glasses

Cited by 63 publications

References 51 publications

Progressive shear band propagation in metallic glasses under compression

Progressive shear band propagation in metallic glasses under compression

Effect of strain rate on yielding strength of a Zr-based bulk metallic glass

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

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