Flaw tolerance of metallic glasses

Chen, Wen; Liu, Ze; Ketkaew, Jittisa; Mota, Rodrigo Miguel Ojeda; Kim, Sung-Hyun; Power, Michael; Samela, William; Schroers, Jan

doi:10.1016/j.actamat.2016.02.002

Cited by 63 publications

(12 citation statements)

References 58 publications

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“…If we take the plastic zone width ( w p in Fig. 5 and Supplementary Figs S3–S6) ahead of the notch root as r p 40, the experimental observations (0.55–0.65 mm) are in line with the predictions. With the effective width of the notched specimens w 1 = 0.8 mm (Fig.…”

Section: Resultssupporting

confidence: 73%

Flaw-induced plastic-flow dynamics in bulk metallic glasses under tension

Chen

Yue

Tsui

et al. 2016

Sci Rep

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Inheriting amorphous atomic structures without crystalline lattices, bulk metallic glasses (BMGs) are known to have superior mechanical properties, such as high strength approaching the ideal value, but are susceptible to catastrophic failures. Understanding the plastic-flow dynamics of BMGs is important for achieving stable plastic flow in order to avoid catastrophic failures, especially under tension, where almost all BMGs demonstrate limited plastic flow with catastrophic failure. Previous findings have shown that the plastic flow of BMGs displays critical dynamics under compression tests, however, the plastic-flow dynamics under tension are still unknown. Here we report that power-law critical dynamics can also be achieved in the plastic flow of tensile BMGs by introducing flaws. Differing from the plastic flow under compression, the flaw-induced plastic flow under tension shows an upward trend in the amplitudes of the load drops with time, resulting in a stable plastic-flow stage with a power-law distribution of the load drop. We found that the flaw-induced plastic flow resulted from the stress gradients around the notch roots, and the stable plastic-flow stage increased with the increase of the stress concentration factor ahead of the notch root. The findings are potentially useful for predicting and avoiding the catastrophic failures in tensile BMGs by tailoring the complex stress fields in practical structural-applications.

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Section: Resultssupporting

confidence: 73%

Flaw-induced plastic-flow dynamics in bulk metallic glasses under tension

Chen

Yue

Tsui

et al. 2016

Sci Rep

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“…Furthermore, very low thermal conductivity of MGs results in a high local temperature in the cutting region especially during high speed cutting. Thus, oxidation and crystallization of MGs may occur [20] which probably affect their amorphous performances [21,22], but this kind of effects is dependent of the properties and volume fraction of the crystalline phases [21][22][23] as well as the sample preparation and evaluation methods [24,25]. In addition, high local temperature will also increase the adhesion between the chip and tool, leading to the formation of built-up edge on the rake face, and thus affect the subsequent cutting process [16,26].…”

Section: Introductionmentioning

confidence: 99%

Nanosecond pulsed laser irradiation induced hierarchical micro/nanostructures on Zr-based metallic glass substrate

et al. 2016

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• Hierarchical micro/nanostructures were fabricated on a metallic glass substrate by nanosecond pulsed laser irradiation.• It retained amorphous characteristic and exhibited uniform element distribution.• Irradiation parameters induced change from cotton-like to particle-like nanostructure.• Formation mechanism and mechanical properties were investigated. A large effective surface area is beneficial to enhance the applications of metallic glasses (MGs) in heterogeneous catalysis and biomedical engineering. For the purpose of increasing effective surface area, in this study, hierarchical micro/nanostructures were fabricated on a Zr-based MG substrate by nanosecond pulsed laser irradiation. Experimental results indicated that a layer of micron-scale laser pulse tracks covered by a cotton-like MG thin film with nanometer-scale microstructure was formed in the laser irradiated region. This hierarchical micro/nanostructures retained amorphous characteristic and exhibited uniform element distribution. Its formation mechanism was investigated by analyzing the laser irradiation process and morphologies. Nanoindentation results indicated that the cotton-like MG thin film was very loose and soft compared to the as-cast MG substrate, showing different plastic deformation behavior. Results from this study indicate that nanosecond pulsed laser irradiation is an effective method to generate hierarchical micro/nanostructures on MG substrates, which can increase their effective surface areas and improve their potential applications as biomaterials and catalysts.

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“…Amorphous solids, including metallic, polymeric, and colloidal glasses, possess complex mechanical response to applied deformations, such as plastic flow [1][2][3][4], strain localization [5][6][7][8][9], creep flow [7,10,11], and fracture [12][13][14]. In crystalline materials, topological defects reflecting the symmetry of the crystalline phase govern response to deformation.…”

Section: Introductionmentioning

confidence: 99%

Effects of cooling rate on particle rearrangement statistics: Rapidly cooled glasses are more ductile and less reversible

et al. 2017

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Amorphous solids, such as metallic, polymeric, and colloidal glasses, display complex spatiotemporal response to applied deformations. In contrast to crystalline solids, during loading, amorphous solids exhibit a smooth crossover from elastic response to plastic flow. In this study, we investigate the mechanical response of binary Lennard-Jones glasses to athermal, quasistatic pure shear as a function of the cooling rate used to prepare them. We find several key results concerning the connection between strain-induced particle rearrangements and mechanical response. We show that the energy loss per strain dU loss /dγ caused by particle rearrangements for more rapidly cooled glasses is larger than that for slowly cooled glasses. We also find that the cumulative energy loss U loss can be used to predict the ductility of glasses even in the putative linear regime of stress versus strain. U loss increases (and the ratio of shear to bulk moduli decreases) with increasing cooling rate, indicating enhanced ductility. In addition, we characterized the degree of reversibility of particle motion during a single shear cycle. We find that irreversible particle motion occurs even in the linear regime of stress versus strain. However, slowly cooled glasses, which undergo smaller rearrangements, are more reversible during a single shear cycle than rapidly cooled glasses. Thus, we show that more ductile glasses are also less reversible.

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Flaw tolerance of metallic glasses

Cited by 63 publications

References 58 publications

Flaw-induced plastic-flow dynamics in bulk metallic glasses under tension

Flaw-induced plastic-flow dynamics in bulk metallic glasses under tension

Nanosecond pulsed laser irradiation induced hierarchical micro/nanostructures on Zr-based metallic glass substrate

Effects of cooling rate on particle rearrangement statistics: Rapidly cooled glasses are more ductile and less reversible

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