Mechanical Properties of Metallic Glasses

Egami, T.; Iwashita, Takuya; Dmowski, W.

doi:10.3390/met3010077

Cited by 126 publications

(90 citation statements)

References 122 publications

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“…It has been established that an applied stress can cause local atomic rearrangement in metallic glasses, resulting in macroscopic deformation. In particular, a flow equation is usually implemented from transition-state theory, in which the strain-rate scales with the stress as  ε ∝ sinh  Ωσ / 2kT ( ) , where  Ω is the activation volume, k is the Boltzmann constant, and T is the temperature [43][44][45]. Over a particular range of stress, this scaling is quite similar to that of Equation 9, which was found to describe our data well (Table 1).…”

Section: Discussionsupporting

confidence: 71%

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Pharr

Suo

Vlassak

2014

Journal of Power Sources

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Silicon is a promising anode material for lithium-ion batteries due to its enormous theoretical energy density. Fracture during electrochemical cycling has limited the practical viability of silicon electrodes, but recent studies indicate that fracture can be prevented by taking advantage of lithiation-induced plasticity. In this paper, we provide experimental insight into the nature of plasticity in amorphous Li x Si thin films. To do so, we vary the rate of lithiation of amorphous silicon thin films and simultaneously measure stresses. An increase in the rate of lithiation results in a corresponding increase in the flow stress. These observations indicate that rate-sensitive plasticity occurs in a-Li x Si electrodes at room temperature and at charging rates typically used in lithium-ion batteries. Using a simple mechanical model, we extract material parameters from our experiments, finding a good fit to a power law relationship between the plastic strain rate and the stress. These observations provide insight into the unusual ability of a-Li x Si to flow plastically, but fracture in a brittle manner. Moreover, the results have direct ramifications concerning the rate-capabilities of silicon electrodes: faster charging rates (i.e., strain rates) result in larger stresses and hence larger driving forces for fracture.

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Section: Discussionsupporting

confidence: 71%

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Pharr

Suo

Vlassak

2014

Journal of Power Sources

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“…Although bulk metallic glasses (BMGs) exhibit attractive mechanical properties, such as high strength, high hardness, and a large elastic strain limit, they usually fail in an apparently brittle manner during deformation at room temperature [1][2][3][4][5][6]. A poor ductility, caused by shear localization and strain/thermal softening, severely restricts their practical applications as structural and functional materials [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites

Song

Cao

et al. 2015

Metals

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Abstract:The microstructures and mechanical properties of (Cu0.5Zr0.5)100−xZnx (x = 0, 1.5, 2.5, 4.5, 7, 10, and 14 at. %) bulk metallic glass (BMG) composites were studied. CuZr martensitic crystals together with minor B2 CuZr and amorphous phases dominate the OPEN ACCESSMetals 2015, 5 2135 microstructures of the as-quenched samples with low Zn additions (x = 0, 1.5, and 2.5 at. %), while B2 CuZr and amorphous phases being accompanied with minor martensitic crystals form at a higher Zn content (x = 4.5, 7, 10, and 14 at. %). The fabricated Cu-Zr-Zn BMG composites exhibit macroscopically appreciable compressive plastic strain and obvious work-hardening due to the formation of multiple shear bands and the deformation-induced martensitic transformation (MT) within B2 crystals. The present BMG composites could be a good candidate as high-performance structural materials.

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“…Compared to the case of creep deformation shown in Figure 5, the anisotropic PDF g2 0 (r) under applied stress is much closer to the affine anisotropic PDF because the deformation is mostly elastic as shown in Figure 7. However, there are significant differences in the first peak area (2-4 Å) of g2 0 (r), which reflect the intrinsically anelastic nature of a glass [11,12]. Figures 5 and 7 cannot be directly compared, because the result in Figure 7 was obtained while the sample was still under stress, whereas that in Figure 5 was obtained after releasing the stress.…”

Section: Resultsmentioning

confidence: 58%

“…A part of this relaxation reflects the non-affine elastic strain because of the disorder in the structure [13,14]. However, such an effect is rather small [12], and much of it originates from bond cutting and forming [7], which occurs even in the nominally elastic regime [10][11][12]. During RT deformation , because the applied stress is below the yield stress, metallic glasses respond to stress elastically following Hook's law.…”

Section: Resultsmentioning

confidence: 99%

Deformation in Metallic Glasses Studied by Synchrotron X-Ray Diffraction

Egami

Yang

Dmowski

2016

Metals

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Abstract:High mechanical strength is one of the superior properties of metallic glasses which render them promising as a structural material. However, understanding the process of mechanical deformation in strongly disordered matter, such as metallic glass, is exceedingly difficult because even an effort to describe the structure qualitatively is hampered by the absence of crystalline periodicity. In spite of such challenges, we demonstrate that high-energy synchrotron X-ray diffraction measurement under stress, using a two-dimensional detector coupled with the anisotropic pair-density function (PDF) analysis, has greatly facilitated the effort of unraveling complex atomic rearrangements involved in the elastic, anelastic, and plastic deformation of metallic glasses. Even though PDF only provides information on the correlation between two atoms and not on many-body correlations, which are often necessary in elucidating various properties, by using stress as means of exciting the system we can garner rich information on the nature of the atomic structure and local atomic rearrangements during deformation in glasses.

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Mechanical Properties of Metallic Glasses

Cited by 126 publications

References 122 publications

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Variation of stress with charging rate due to strain-rate sensitivity of silicon electrodes of Li-ion batteries

Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites

Deformation in Metallic Glasses Studied by Synchrotron X-Ray Diffraction

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