Mean stress effects on flow localization and failure in a bulk metallic glass

Flores, Katharine M.; Dauskardt, Reinhold H.

doi:10.1016/s1359-6454(01)00125-2

Cited by 204 publications

(132 citation statements)

References 19 publications

Supporting

Mentioning

121

Contrasting

Order By: Relevance

“…It is currently accepted that shear band initiation in glassy alloys is related to free volume coalescence. 33,35) At cryogenic temperatures, increased stiffness of the atomic bond makes squeezed free volume coalescence more difficult, since the mobility of the free volume at cryogenic temperature is much lower than that at room temperature. The coalescence of the free volume requires a higher applied load, resulting in the increase of the tensile strength at cryogenic temperatures.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Tensile Strength and Plasticity of Zr-Cu-Al Bulk Glassy Alloys at Cryogenic Temperatures

et al. 2009

View full text Add to dashboard Cite

No data are available about mechanical behavior of bulk glassy alloys (BGAs) in tension at cryogenic temperatures. In this study, we investigated the effect of temperature on the mechanical behavior of ternary eutectic and hypoeutectic Zr-Cu-Al BGAs fabricated by an arc tilt casting method. Tensile tests were performed for the BGA plates with gauge dimensions of 5 mm in length, 1.2 mm in width and 0.5 mm in thickness at temperatures of 295, 223, 173 and 77 K, at an initial strain rate of 5 Â 10 À4 s À1 . Measurements of elastic parameters were also made at temperatures from 97 to 342 K by an ultrasonic pulse method. It is found that the tensile strength and elongation for both BGAs increase with decreasing testing temperature, which is reported for the first time under a tensile condition. At cryogenic temperatures, the tensile elongation of the hypoeutectic Zr 59 Cu 31 Al 10 BGA tends to be higher than that of the eutectic Zr 50 Cu 40 Al 10 BGA, although the difference is small. Multiple shear bands are observed on the side surface deformed at lower temperatures. The Young's and shear moduli, and Debye temperature monotonically increase with decreasing temperature. This indicates that the BGA becomes rigid and the effective atomic distance decreases at cryogenic temperatures, leading to the increase of the tensile strength at cryogenic temperatures.

show abstract

Section: Resultsmentioning

confidence: 99%

Enhanced Tensile Strength and Plasticity of Zr-Cu-Al Bulk Glassy Alloys at Cryogenic Temperatures

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Conventional x-ray diffraction verified that all the samples were fully amorphous before the spallation experiments. Table I presents the mechanical properties of Vit 1 extracted from other literatures, 27,33,34 where q is the density, E the elastic modulus, G the shear modulus, the Possion ratio, c L the longitudinal wave speed, and c t the shear wave speed.…”

Section: Methodsmentioning

confidence: 99%

How does spallation microdamage nucleate in bulk amorphous alloys under shock loading?

Huang

Zhong

Zhang

et al. 2011

Journal of Applied Physics

View full text Add to dashboard Cite

Transmission electron microscopy of the amorphization of copper indium diselenide by in situ ion irradiation J. Appl. Phys. 111, 053510 (2012) Diffusion-controlled formation mechanism of dual-phase structure during Al induced crystallization of SiGe Appl. Phys. Lett. 100, 071908 (2012) Local structure of nitrogen in N-doped amorphous and crystalline GeTe Appl. Phys. Lett. 100, 061910 (2012) Facile creation of bio-inspired superhydrophobic Ce-based metallic glass surfaces Appl. Phys. Lett. 99, 261905 (2011) Unexpected short-and medium-range atomic structure of sputtered amorphous silicon upon thermal annealing J. Appl. Phys. 110, 096104 (2011) Additional information on J. Appl. Phys. Specially designed plate-impact experiments have been conducted on a Zr-based amorphous alloy using a single-stage light gas gun. To understand the microdamage nucleation process in the material, the samples are subjected to dynamic tensile loadings of identical amplitude ($ 3.18 GPa) but with different durations (83-201 ns). A cellular pattern with an equiaxed shape is observed on the spallation surface, which shows that spallation in the tested amorphous alloy is a typical ductile fracture and that microvoids have been nucleated during the process. Based on the observed fracture morphologies of the spallation surface and free-volume theory, we propose a microvoid nucleation model of bulk amorphous alloys. It is found that nucleation of microvoids at the early stage of spallation in amorphous alloys results from diffusion and coalescence of free volume, and that high mean tensile stress plays a dominant role in microvoid nucleation.

show abstract

“…Early work [2][3][4][5] identified two potential origins of shear localization: thermal expansion of molar volume induced by adiabatic heating which causes the free volume to increase, and structural disordering a͒ Author to whom correspondence should be addressed; electronic mail: marios@caltech.edu in the liquid induced by shear which contributes to free volume creation. Although significant heating is generated during shear localization, recent evidence [6][7][8][9] indicates that adiabatic heating is not the prime origin, as localization appears to be triggered by structural disordering. A model based on free volume production dictated by both adiabatic heating and structural disordering would form an appropriate basis for understanding the mechanisms triggering shear localization.…”

Section: Introductionmentioning

confidence: 99%

Modeling the transient flow of undercooled glass-forming liquids

Demetriou

Johnson

2004

Journal of Applied Physics

View full text Add to dashboard Cite

In a recent experimental study on flow behavior of Vitreloy-1 (Zr 41.25 Ti 13.75 Cu 12.5 Ni 10 Be 22.5 ), three distinct modes of flow are suggested: Newtonian, non-Newtonian, and localized flow. In a subsequent study, the experimental flow data is utilized in a self-consistent manner to develop a rate equation to govern local free volume production. In the present study the production-rate equation is transformed into a transport equation that can be coupled with momentum and energy transport via viscosity to formulate a model capable to govern the flow of undercooled glass forming liquids. The model is implemented to study the flow behavior of undercooled Vitreloy-1 melt. For a temperature of 700 K and shear loading of 1.0 MPa, the model predicts that the flow profile gradually stabilizes to its Newtonian limit while the liquid is maintained in structural and thermal equilibrium. For the conditions of 675 K and 100 MPa, the model predicts that the flow profile departs from its Newtonian limit and gradually stabilizes to a non-Newtonian limit. The non-Newtonian profile is evaluated independently by considering structurally quasistatic conditions, which yield the shear-rate dependency of flow. For the conditions of 650 K and 2.0 GPa, the model predicts that the flow continuously localizes and ultimately accelerates unconstrained, while the system is driven out of structural and thermal equilibration towards an unstable state associated with free volume generation, viscosity degradation, and temperature rise. The computed temperature and shear rate evolutions for the three distinct flow modes are superimposed on a temperature-shear rate diagram and appear to computationally reproduce the experimental flow map. The system's structural state that appears to dictate flow behavior is quantified by a dimensionless number, which results from a time scale analysis of the free volume production equation.

show abstract

Mean stress effects on flow localization and failure in a bulk metallic glass

Cited by 204 publications

References 19 publications

Enhanced Tensile Strength and Plasticity of Zr-Cu-Al Bulk Glassy Alloys at Cryogenic Temperatures

Enhanced Tensile Strength and Plasticity of Zr-Cu-Al Bulk Glassy Alloys at Cryogenic Temperatures

How does spallation microdamage nucleate in bulk amorphous alloys under shock loading?

Modeling the transient flow of undercooled glass-forming liquids

Contact Info

Product

Resources

About