An instability index of shear band for plasticity in metallic glasses

Han, Zhen; Wu, Wenfei; Li, Y.; Wei, Yujie; Gao, Huajian

doi:10.1016/j.actamat.2008.11.018

Cited by 187 publications

(148 citation statements)

References 29 publications

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“…At the same time, the released elastic energy stored in the metallic glass sample and testing machine system due to the stress drop can be transformed into heat to increase the temperature of shear layer and further decrease the viscosity of shear layer. If the energy release in a shear band overcoming the critical plastic energy c [35][36][37] or the temperature rise in shear layer reaching a critical value [28,38], shear band will not be arrested and failure of BMG samples will occur. Usually, elastic unloading of the stress [28], geometric constrainer [39] and friction from pushrod/material interface [40], etc.…”

Section: Discussionmentioning

confidence: 99%

Ambient temperature embrittlement of a Zr-based bulk metallic glass

Jiang¹,

Wang²,

Jiang³

et al. 2012

Materials Science and Engineering: A

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a b s t r a c tThree-point bending experiments were performed on Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 (Vit105) bulk metallic glass (BMGs) over a wide range of ambient temperatures varying from the liquid nitrogen temperature (77 K) to about boiling water temperature (370 K). The results demonstrated that the flexural strength of the Zrbased BMG monotonously increased with decreasing of test temperature, whereas plastic deformation ability displayed a maximum at a moderate temperature (about room temperature). That is, the plastic deformation ability was deteriorated by either higher or lower temperature than room temperature through affecting shear band nucleation and propagation within materials respectively.

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Section: Discussionmentioning

confidence: 99%

Ambient temperature embrittlement of a Zr-based bulk metallic glass

Jiang¹,

Wang²,

Jiang³

et al. 2012

Materials Science and Engineering: A

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“…A custom loading fixture 18 ensured uniaxial loading of the specimens and increased the stiffness of the test frame since the ductility of metallic glasses is known to depend on both the misalignment of the specimen 19 and the ratio of the specimen to frame stiffnesses. 20 The load data were acquired using a Kistler 9031A piezoelectric load cell (60 kN), a Kistler 5010B charge amplifier (180 kHz low pass filter), and a HiTechniques Synergy P data acquisition system (40 kHz low pass filter) with a data collection rate of 100 kHz. The data from the fracture event were used as the unit impulse response for the purposes of Wiener filtering.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

Wright

Liu

et al. 2016

Journal of Applied Physics

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Two distinct types of slip events occur during serrated plastic flow of bulk metallic glasses. These events are distinguished not only by their size but also by distinct stress drop rate profiles. Small stress drop serrations have fluctuating stress drop rates (with maximum stress drop rates ranging from 0.3–1 GPa/s), indicating progressive or intermittent propagation of a shear band. The large stress drop serrations are characterized by sharply peaked stress drop rate profiles (with maximum stress drop rates of 1–100 GPa/s). The propagation of a large slip is preceded by a slowly rising stress drop rate that is presumably due to the percolation of slipping weak spots prior to the initiation of shear over the entire shear plane. The onset of the rapid shear event is accompanied by a burst of acoustic emission. These large slips correspond to simultaneous shear with uniform sliding as confirmed by direct high-speed imaging and image correlation. Both small and large slip events occur throughout plastic deformation. The significant differences between these two types require that they be carefully distinguished in both modeling and experimental efforts.

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“…The atomic diffusion perpendicular to the loading force constantly fills the new free volume, causing a high creep strain and high steady state creep rate, as shown in Figure 2. Here, it should be mentioned that the mechanical properties of metallic glass are strongly dependent on the sample size and the stiffness of the testing machine [54][55][56][57][58]. Han et al [54] suggested that catastrophic failure is dominated by a shear-band instability index which is proportional to the sample size and inversely proportional to the machine stiffness.…”

Section: Resultsmentioning

confidence: 99%

“…Here, it should be mentioned that the mechanical properties of metallic glass are strongly dependent on the sample size and the stiffness of the testing machine [54][55][56][57][58]. Han et al [54] suggested that catastrophic failure is dominated by a shear-band instability index which is proportional to the sample size and inversely proportional to the machine stiffness. This index can provide more understanding about the plastic deformation mechanism of BMGs and is helpful for designing glass-forming alloy systems which possess plasticity/ductility [54].…”

Section: Resultsmentioning

confidence: 99%

Tensile Creep Characterization and Prediction of Zr-Based Metallic Glass at High Temperatures

Wang

Pan

Shi

et al. 2018

Metals

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Abstract:The high temperature creep behaviors of a Zr-based bulk metallic glass (BMG) are studied by uniaxial tensile creep experiments under applied stresses of 50-180 MPa at temperatures of 660-700 K. The microstructural observations of the BMG samples after creep tests show that crystalline phases can be detected under high temperature or high applied stress. Constitutive models for predicting the high temperature creep behaviors of the studied Zr-based BMG are established based on the θ projection method. The creep activation energy and stress exponent are also calculated to establish the creep model. The parameters of the established models are found to be closely associated with the applied stress and temperature. The results show an excellent agreement between the measured and predicted results, confirming the validity of the established model to accurately estimate the high temperature creep curves for the Zr-based BMG. Moreover, based on the classical diffusion creep theory, a schematic model is proposed to describe the creep behaviors of BMGs from the framework of free volume theory.

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An instability index of shear band for plasticity in metallic glasses

Cited by 187 publications

References 29 publications

Ambient temperature embrittlement of a Zr-based bulk metallic glass

Ambient temperature embrittlement of a Zr-based bulk metallic glass

Experimental evidence for both progressive and simultaneous shear during quasistatic compression of a bulk metallic glass

Tensile Creep Characterization and Prediction of Zr-Based Metallic Glass at High Temperatures

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