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

Li, Mingcan; Jiang, Minqiang; Yang, Sen; Jiang, F.; Lin, He; Sun, Jun

doi:10.1016/j.msea.2016.10.081

Cited by 58 publications

(26 citation statements)

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“…In such a scenario, the stress overshoot becomes further weak. This is consistent [26,32]. As mentioned above, for a fixed equivalent strain rate, a higher peakload corresponds to a larger indentation size within the same loading time.…”

Section: Contents Lists Available At Sciencedirectsupporting

confidence: 84%

“…Upon loading, the liquid-like regions will act as the potential sites of shear transformation zones (STZs), which are the unit carriers of plasticity in metallic glasses [25,26]. As the external stress keeps increasing, more and more STZs will be activated, and meanwhile the associated atomic rearrangements in the STZs can relax the local stress and reduce the local energy concentration.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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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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Section: Contents Lists Available At Sciencedirectsupporting

confidence: 84%

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 critical strain rate may exist to control this transition. Li et al [24] estimated such strain rate to be about 450 s −1 , while our previous study proposed that the critical value was in the range from 10 1 s −1 to 10 2 s −1 . The examination of the critical strain rate needs further investigation at intermediate strain rate.…”

Section: Discussionmentioning

confidence: 80%

“…It is interesting that only shearing traces and several shear bands are observed on the slip plane ( Fig. 5d1), which is quite different from the classical fracture surfaces covered by vein-like patterns [10,19,21,24,39]. However, typical vein-like patterns are observed in the fractured sample under 5 × 10 −3 s −1 (Fig.…”

Section: Shear Banding and Cracking Behaviors In Ductile Bmgsmentioning

confidence: 84%

“…Thus, the various deformation modes in BMGs are determined by different shear banding behaviors. Extensive reports have shown that the shear banding behaviors and hereby deformation modes are influenced by various factors, including material compositions [14][15][16], loading rate [17][18][19][20][21][22][23][24] and temperature [25][26][27][28]. In addition, sample size [29][30][31] and stress state during loading [32,33] also affect deformation mode.…”

Section: Introductionmentioning

confidence: 99%

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A comparative study of the rate effect on deformation mode in ductile and brittle bulk metallic glasses

Zhou

Hou

et al. 2018

Intermetallics

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A B S T R A C TThe rate effect on the deformation mode of bulk metallic glasses (BMGs) is investigated by a comparative study between ductile and brittle compositions via real-time photographing. The strain-rate controls the deformation mode transition from shear-dominated sliding under quasi-static compression to cracking-dominated fracture under dynamic compression. In ductile BMGs, progressive sliding occurs at lower strain rate and contributes to a stable deformation manner. In brittle BMGs, however, unstable deformation occurs through rapid sliding even under quasi-static compression. Both ductile and brittle BMGs undergo unstable deformation under dynamic compression. The rate-dependent and composition-dependent tendency of stable or unstable deformation is well characterized by a model based on the ratio of the applied strain energy to the critical dissipation energy at the local shear banding region.

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Experimental Investigation of Zr‐Based Amorphous Alloy as a Shaped Charge Liner

Shi

Huang

2022

Propellants Explo Pyrotec

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This study aimed to investigate the mechanical properties of Zr-based amorphous alloy at high strain rates and its use as a shaped charge liner. A split Hopkinson pressure bar (SHPB) was used to carry out dynamic mechanical performance tests, and a scanning electron microscope (SEM) was used to observe the fracture morphology of the test piece. The X-ray test of the jet formation and the static penetration test of the Zr-based amorphous alloy jet were performed. It was found that the amorphous alloy material exhibits typical brittle fracture characteristics under high strain-rate compression. As the strain rate increases, molten droplet-like structures appear in the frac-ture morphology, and the melting area is proportional to the strain rate. The Zr-based amorphous alloy liner forms a non-cohesive jet driven by explosive explosion. The actual projection angle of the liner is slightly larger than the theoretical value of Taylor's projection angle because of the unique mechanical properties and fracture mechanism, while the collapse angle is slightly smaller. Compared with copper jet penetrating concrete, the aperture of Zr-based amorphous alloy jet is increased by 58 % and the caving volume is increased by 32 times. The results provide reference for the application of Zr-based amorphous alloy in the field of shaped charge liner.

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

Cited by 58 publications

References 57 publications

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

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

A comparative study of the rate effect on deformation mode in ductile and brittle bulk metallic glasses

Experimental Investigation of Zr‐Based Amorphous Alloy as a Shaped Charge Liner

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