On the strain rate sensitivity of plastic flow in metallic glasses

Bhattacharyya, Abir; Singh, Govindra; Prasad, K. Eswar; Narasimhan, R.; Ramamurty, Upadrasta

doi:10.1016/j.msea.2014.12.004

Cited by 96 publications

(30 citation statements)

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“…This indicates that the Oliver and Pharr method [21], which was derived from purely elastic solution, may not be reasonable for the hardness calculation in the present case. Moreover, it is addressed that the Meyer's hardness method can correct the minor error due to the pile-up effect [6,19]. Therefore, Meyer's hardness that is defined as H = P max /A t is adopted.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

“…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].…”

Section: Introductionmentioning

confidence: 99%

“…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).…”

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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 Sciencedirectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 97%

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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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“…[2,[85][86][87][88][89][90]93,98,110,113,[116][117][118][119][120][121][122][136][137][138][139][140]. (b) fracture toughness [85,89,90,110,112,[141][142][143][144][145][146][147], and (c) strain-rate sensitivity [105,106,[148][149][150][151][152] of organic crystals with other classes of materials.…”

Section: Discussionmentioning

confidence: 99%

Crystal Indentation Hardness

2018

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Section: Discussionmentioning

confidence: 99%

Indentation Plasticity and Fracture Studies of Organic Crystals

Mannepalli

Kiran

2017

Crystals

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This review article summarizes the recent advances in measuring and understanding the indentation-induced plastic deformation and fracture behavior of single crystals of a wide variety of organic molecules and pharmaceutical compounds. The importance of hardness measurement for molecular crystals at the nanoscale, methods and models used so far to analyze and estimate the hardness of the crystals, factors affecting the indentation hardness of organic crystals, correlation of the mechanical properties to their underlying crystal packing, and fracture toughness studies of molecular crystals are reviewed.

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On the strain rate sensitivity of plastic flow in metallic glasses

Cited by 96 publications

References 54 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

Crystal Indentation Hardness

Indentation Plasticity and Fracture Studies of Organic Crystals

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