The correlation between weakest configurations and yield strength of Zr-based metallic glasses

Li, Mingcan; Jiang, Minqiang; Ding, Guangliang; Peng, Zhen; Jiang, F.; Lin, He; Sun, Jun

doi:10.1016/j.jnoncrysol.2017.04.021

Cited by 16 publications

(4 citation statements)

References 66 publications

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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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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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“…Weakest configurations [19], bond exchange [20] processes, and flow units [9] were introduced as current conceptions that treat MGs's atomic structure from a point of view in which weakly bonded (WB) atoms play a key role. Substantially, they bring the picture of an alloy composed by atomic motifs formed by strongly bonded (SB) atoms -also already described in the literature as an elastic-like matrix -in which liquid-like portions of the solid made up of WB atoms [9] are immersed.…”

Section: B Application Of the ML Modelmentioning

confidence: 99%

“…The resulting overview of chemical interactions allowed qualitative and quantitative analysis of deformation behavior from the perspective of concepts currently used to describe structural heterogeneity and atomic-scale flow mechanisms in these MGs. Among which stand out: the so-termed weakest configurations [19], conceived as well-defined less stiff regions supposed to exist in the solid bulk; bond exchange [20] processes to which weakly bonded atoms within these regions would be more susceptible as marked rearrangements; and the current broader notion of flow units [9], which are defined as regions that mainly contribute to the viscoelastic features of MGs.…”

Section: Introductionmentioning

confidence: 99%

Chemical Bonding in Metallic Glasses from Machine Learning and Crystal Orbital Hamilton Population

Ferreira

2020

Preprint

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The chemistry (composition and bonding information) of metallic glasses (MGs) is at least as important as structural topology for understanding their properties and production/processing peculiarities. This article reports a machine learning (ML)-based approach that brings an unprecedented "big picture" view of chemical bond strengths in MGs of a prototypical alloy system. The connection between electronic structure and chemical bonding is given by crystal orbital Hamilton population (COHP) analysis within the framework of density functional theory (DFT). The stated comprehensive overview is made possible through a combination of efficient quantitative estimate of bond strengths supplied by COHP analysis, representative statistics regarding structure in terms of atomic configurations achieved with classical molecular dynamics simulations, and the smooth overlap of atomic positions (SOAP) descriptor. The study is supplemented by an application of that ML model under the scope of mechanical loading, in which predicted bond strengths enabled atom categorization based on a descriptor of the short-range order possessing a superior chemical sense; a key component to uncover structural/chemical heterogeneity and its influence on mechanical relaxation processes and atomic scale flow mechanisms in MGs.

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“…Therefore, the Zr-based amorphous alloy is one of the most studied bulk amorphous alloy systems. However, room-temperature brittleness and strain softening have always been weaknesses in the mechanical properties of Zr-based amorphous alloys [24][25][26]. Thus, the application of this material in the engineering field is seriously limited.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Response of Zr51.9Cu23.3Ni10.5Al14.3 Metallic Glass Ribbon under Varying Strain Rates

Li,

Wu,

et al. 2024

Metals

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In this work, we investigated the mechanical behavior of a low-cost Zr51.9Cu23.3Ni10.5Al14.3 (at. %) metallic glass ribbon prepared with industrial-grade material through the melt-spinning method. The ribbons have good appearances and almost no defects. The mechanical behavior associated with the corresponding microstructure of the ribbon was tested at different strain rates. Striation and veining patterns were observed in the crack propagation zone and the fast fracture zone. The results show that the tensile strength of the ribbons exceeds 1 GPa. Therefore, they are considered to have good potential for industrial applications. This study could contribute to the preparation of low-cost bulk metallic glass.

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The correlation between weakest configurations and yield strength of Zr-based metallic glasses

Cited by 16 publications

References 66 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

Chemical Bonding in Metallic Glasses from Machine Learning and Crystal Orbital Hamilton Population

Mechanical Response of Zr51.9Cu23.3Ni10.5Al14.3 Metallic Glass Ribbon under Varying Strain Rates

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