A Finite-Deformation Constitutive Model of Bulk Metallic Glass Plasticity

Yang, Qiang; Mota, Alejandro; Ortiz, Michael

doi:10.1007/s00466-005-0690-5

Cited by 86 publications

(61 citation statements)

References 35 publications

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“…Here, a is a geometrical factor of order unity, g 0 is the viscosity of the liquid at the high-temperature limit, r 0 is a reference stress, and the temperature-dependent b(T) is a stretching exponent fitting from the data [56]. For Vit1 BMG [59], a = 0.105, g 0 = 4 Â 10 À5 Pa s, r 0 = 0.25r y , r y is the yield stress at room temperature ($1.9 GPa) and b(T) = 1.0 À a g (T À T g ) 3 , with a g = 4.325 Â 10 À10 K À3 and T g = 293 K. Considering that the BMG used in the present work has a similar composition to Vit 1, the above parameters can be used in the current calculations. According to Eq.…”

Section: Theoretical Analysis Based On Free Volume Theorymentioning

confidence: 99%

A thermoplastic forming map of a Zr-based bulk metallic glass

Chen

Jiang

et al. 2013

Acta Materialia

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A thermoplastic forming (TPF) map of a Zr 35 Ti 30 Be 26.75 Cu 8.25 bulk metallic glass was constructed through systematic hot-embossing experiments, spanning a wide range of strain rates and temperatures in the supercooled liquid region. By comparison with the corresponding deformation map, it is found that Newtonian flow, non-Newtonian flow and inhomogeneous flow regions correspond well to fully filled, partially filled and non-filled regions, respectively, in the hot-embossing TPF map. Furthermore, the spatio-temporally homogeneous flow facilitates the thermoplastic formabillity of the Zr-based bulk metallic glass, which is rationalized in terms of free volume theory as well as by finite element simulations. Finally, our results are corroborated by potential application tests.

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Section: Theoretical Analysis Based On Free Volume Theorymentioning

confidence: 99%

A thermoplastic forming map of a Zr-based bulk metallic glass

Chen

Jiang

et al. 2013

Acta Materialia

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“…34,45 During spallation, the material is subjected to dynamic tensile stress of several GPa or higher. As the mean tensile stress causes volume dilation, the average free volume increases.…”

Section: Increase Of Free Volume Contentmentioning

confidence: 99%

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

Huang

Zhong

Zhang

et al. 2011

Journal of Applied Physics

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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.

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“…CoheneGrest model (Grest and Cohen, 1981;Yang et al, 2006), where T is the temperature, d 1 , d 2 , and T ref are material parameters. x is the current free volume concentration, and the evolution of x relies on applied stress, heat and diffusion (Spaepen, 1977;Argon, 1979;Huang et al, 2002;Thamburaja and Ekambaram, 2007;Li et al, 2013).…”

Section: Constitutive Relationsmentioning

confidence: 99%

“…(16) in the fan region (p/4 À f/2 < q < 3p/4 À f/2) and is vanishing when v / 0.5. The mechanical and material parameters used in the following analyses are given as (Yang et al, 2006;Li et al, 2013): It is known that, for typical Zr-based MGs, its Poisson's ratio is around 0.35 and its pressure sensitivity factor m and dilatancy factor b are estimated about 0.1 (Sun et al, 2010b). Actually, for different MGs, the values of Poisson's ratio can range from 0.3 to nearly 0.5, and the pressure sensitivity and the dilatancy can change from minor (i.e.…”

Section: Plastic Zone Size and Shapementioning

confidence: 99%

Nature of crack-tip plastic zone in metallic glasses

Chen

Dai

2016

International Journal of Plasticity

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a b s t r a c tThe fracture of metallic glasses(MGs) can be induced by shear banding in a ductile mode or by cavitation in a brittle way. Plastic zone in front of a crack tip, which is greatly involved with localized shear band, cavitation and the resultant fracture morphology, is a key clue to unveil the secrets of the intrinsic ductility and fracture. However, the characteristics of plastic zone, i.e., stress and strain distributions, size and shape, have not been clearly unraveled for MGs so far. In this paper, an analytical solution of the plastic zone for mode I crack under plane strain condition is derived through J-integral based on a slip line field analysis and shape approximation, by taking pressure-sensitivity, dilatancy, and structural evolution into account. Two length scales of the plastic zone, i.e. the maximum radius R max and the radius along the crack line direction R x , are revealed to control shear flow instability and cavitation, and therefore failure modes. According to shear transformation zone (STZ) based free volume evolution dynamics, the critical values of the mode I stress intensity factor and the plastic zone size at crack initiation are obtained. The effects of Poisson's ratio, pressure sensitivity, and dilatancy on the stress/strain distributions, and the size of plastic zone are elucidated. It is found that larger Poisson's ratio and smaller dilatancy lead to higher fracture toughness and 'slender' critical plastic zone, facilitating a good ductility. The internal correlations of the fracture pattern (i.e. dimple structure) with the plastic zone are established, where the size of the fracture pattern is quantitatively characterized by the critical length of plastic zone. To be further, a shape change of the critical plastic zone from 'slender' (apt to shear plastic flow) to 'chubby' (inclined to cavitation) is revealed with increasing dilatancy or decreasing Poisson's ratio, which might shed light on the underlying mechanism of ductile-to-brittle transition in MGs.

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A Finite-Deformation Constitutive Model of Bulk Metallic Glass Plasticity

Cited by 86 publications

References 35 publications

A thermoplastic forming map of a Zr-based bulk metallic glass

A thermoplastic forming map of a Zr-based bulk metallic glass

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

Nature of crack-tip plastic zone in metallic glasses

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