Correlation between fracture surface morphology and toughness in Zr-based bulk metallic glasses

Suh, Jin-Yoo; Conner, R.D.; Kim, C. Paul; Demetriou, Marios D.; Johnson, William L.

doi:10.1557/jmr.2010.0112

Cited by 55 publications

(27 citation statements)

References 32 publications

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“…As seen, L rough increases with increasing T R . A one-to-one correspondence between K IC vs. L rough is evident from the data in Table 1, as first reported by Suh et al (25). Such correspondence is shown graphically in Fig.…”

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confidence: 85%

Origin of Embrittlement of Metallic Glasses

Demetriou¹,

Garrett²,

Johnson³

2018

Structural Integrity

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Owing to their glassy nature, metallic glasses demonstrate a toughness that is extremely sensitive to the frozen-in configurational state. This sensitivity gives rise to "annealing embrittlement," which is often severe and in many respects limits the technological advancement of these materials. Here, equilibrium configurations (i.e., "inherent states") of a metallic glass are established around the glass transition, and the configurational properties along with the planestrain fracture toughness are evaluated to associate the intrinsic glass toughness with the inherent state properties and identify the fundamental origin of embrittlement. The established correlations reveal a one-to-one correspondence between toughness and shear modulus continuous over a broad range of inherent states, suggesting that annealing embrittlement is controlled almost solely by an increasing resistance to shear flow. This annealing embrittlement sensitivity is shown to vary substantially between metallic glass compositions, and appears to correlate well with the fragility of the metallic glass.ductility | amorphous metal | fracture toughness U nlike conventional oxide glasses, metallic glasses can be considerably tougher, often approaching values typical of engineering metals. Specifically, the toughness of metallic glasses can vary from values as high as 150-200 MPa·m 1/2 (1, 2), comparable to low-carbon steels, to as low as 2-3 MPa·m 1/2 (3, 4), which is more typical of oxide glasses. But, like any glass, metallic glasses tend to embrittle when annealed around the glass transition, as evidenced by a measurable drop in their toughness and their capacity to deform plastically. This phenomenon, typically referred to as annealing embrittlement, has broad scientific and technological ramifications. From a technological perspective, annealing embrittlement is at least partly responsible for the large variability in toughness observed when the glass is quenched at different cooling rates (5-7), thereby limiting their mechanical performance and engineering reliability. From a physics perspective, the physical origin of annealing embrittlement is still a topic of debate and controversy that is far from being settled, as varying and contradictory theories have been proposed by various groups over the years.Wu and Spaepen (8) made the first attempt to relate the toughness of the metallic glass to its structure. They postulated that annealing embrittlement is associated with a reduction in "free volume" in the glass atomic structure as it is relaxed at incrementally lower temperatures, degrading its capacity for plastic rearrangement and flow. Their concept has been adopted by several other groups (9-11). In recent years, an alternative concept has emerged linking the toughness of the metallic glass to its elastic constants, particularly to the ratio of the bulk to shear modulus (or equivalently to Poisson's ratio). This ratio is used to relate the resistances to cavitation and shear flow, respectively (12). Unlike free volume, the elastic con...

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supporting

confidence: 85%

Origin of Embrittlement of Metallic Glasses

Demetriou¹,

Garrett²,

Johnson³

2018

Structural Integrity

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“…The mechanism of toughness in metallic glasses arises from blunting propagating cracks by plastic shear-band sliding at the crack tip and is generally reflected by the roughness of the fracture surface. 19 As shear bands multiply in number and grow in length from the notch, they produce multiple shear offsets that result in the jagged surface of the plasticity regime that follows the initial sliding regime. Once shear bands reach a critical sliding strain, cavitation and crack opening take over, transforming the shear band in to an emerging crack.…”

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Effect of microalloying on the toughness of metallic glasses

Garrett

Demetriou

Chen

et al. 2012

Applied Physics Letters

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Charge trapping in [poly-(2-methoxyl),5-(3,77dimethyloctyloxy)] paraphenylenevinylene synthesized in different routes affected by the energetical distribution of trapping states J. Appl. Phys. 113, 013104 (2013) Simultaneous iron gettering and passivation of p-type monocrystalline silicon using a negatively charged aluminum-doped dielectric Appl. Phys. Lett. 101, 252105 (2012) Facile characterization of ripple domains on exfoliated graphene Rev. Sci. Instrum. 83, 073905 (2012) Improved memory characteristics by NH3-nitrided GdO as charge storage layer for nonvolatile memory applications Appl. Phys. Lett. 101, 033501 (2012) Mn-activated K2ZrF6 and Na2ZrF6 phosphors: Sharp red and oscillatory blue-green emissions

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“…Based on the hyperelastic model, the elastic energy stored in the specimen can be transferred to the crack tip, and thus support the crack propagation. When the crack penetrates into the glassy phase, a local energy flux with a characteristic length of γ, which is from At the beginning of crack propagation, i.e., the point I in Figure 4, the jagged patterns are believed to be related to the crack formation and propagation processes [23,29,30], although the origin of the jagged patterns is still not yet clear. Suh et al [29] conjectured that the nonplanar ridged fatigue fracture surfaces were a necessary condition for the formation of a jagged rough zone.…”

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Reduced Fracture Toughness of Metallic Glass at Cryogenic Temperature

Zhou

Liu

Han

et al. 2017

Metals

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Abstract:The effects of cryogenic temperature on the toughness of a Zr-based metallic glass are investigated. Based on three-dimensional fracture morphologies at different temperatures, the crack formation and propagation are analyzed. Through the calculation of the shear transformation zone volume, the shear modulus and bulk modulus of the metallic glass at different temperatures and the crack formation mechanism associated with the temperature is discussed. Once the crack commences propagation, the hyperelasticity model is used to elucidate the fractographic evolution of crack propagation.

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Correlation between fracture surface morphology and toughness in Zr-based bulk metallic glasses

Cited by 55 publications

References 32 publications

Origin of Embrittlement of Metallic Glasses

Origin of Embrittlement of Metallic Glasses

Effect of microalloying on the toughness of metallic glasses

Reduced Fracture Toughness of Metallic Glass at Cryogenic Temperature

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