Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge

Kaltenboeck, Georg; Harris, Thomas I.; Sun, Kerry; Tran, Thomas; Chang, Gregory; Schramm, Joseph P.; Demetriou, Marios D.; Johnson, William L.

doi:10.1038/srep06441

Cited by 40 publications

(21 citation statements)

References 17 publications

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“…This alloy crystallizes to a single crystalline phase having the same composition as the parent liquid, that is, by polymorphic crystallization, not typical of most metallic glass formers. Recent measurements of the multiphase eutectic growth velocity near T * in several easy glass formers by time-resolved infrared imaging 51 give relatively high velocities ranging from several cm s −1 for Zr-based bulk glasses up to several m s −1 for high-GFA eutectic Ni-alloys (see ref. 51 and also J.P. Schramm, G. Kaltenboeck, M.D.…”

Section: Discussionmentioning

confidence: 99%

“…Recent measurements of the multiphase eutectic growth velocity near T * in several easy glass formers by time-resolved infrared imaging 51 give relatively high velocities ranging from several cm s −1 for Zr-based bulk glasses up to several m s −1 for high-GFA eutectic Ni-alloys (see ref. 51 and also J.P. Schramm, G. Kaltenboeck, M.D. Demetriou, and W.L.…”

Section: Discussionmentioning

confidence: 99%

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Quantifying the origin of metallic glass formation

Na²,

2016

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The waiting time to form a crystal in a unit volume of homogeneous undercooled liquid exhibits a pronounced minimum τX* at a ‘nose temperature' T* located between the glass transition temperature Tg, and the crystal melting temperature, TL. Turnbull argued that τX* should increase rapidly with the dimensionless ratio trg=Tg/TL. Angell introduced a dimensionless ‘fragility parameter', m, to characterize the fall of atomic mobility with temperature above Tg. Both trg and m are widely thought to play a significant role in determining τX*. Here we survey and assess reported data for TL, Tg, trg, m and τX* for a broad range of metallic glasses with widely varying τX*. By analysing this database, we derive a simple empirical expression for τX*(trg, m) that depends exponentially on trg and m, and two fitting parameters. A statistical analysis shows that knowledge of trg and m alone is therefore sufficient to predict τX* within estimated experimental errors. Surprisingly, the liquid/crystal interfacial free energy does not appear in this expression for τX*.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Quantifying the origin of metallic glass formation

Na²,

2016

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“…However, the high cost to fabricate the micro/ nanostructured molds as well as the limited mold-life-times hinders its wide applications [2]. Furthermore, crystallization may also occur during the thermoplastic shaping because it is very hard to control a uniform forming temperature [30], especially for MGs with a narrow supercooled temperature region.…”

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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“…The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming process may become a promising manufacturing platform for strong metals [13][14][15].…”

Section: Conventional (Classic) Methods For Fabrication Of Mgs Partsmentioning

confidence: 99%

An overview on the conventional and nonconventional methods for manufacturing the metallic glasses

et al. 2017

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Abstract. Metallic glasses (MGs), first discovered in 1959 at Caltech are currently among the most studied metallic materials. MGs called also glassy metals, amorphous metals, liquid metals, are considered to be among the materials of the future. The "classic" methods for industrialization of MGs are : end-casting in copper molds and protected environment, die forging , atomization for obtaining MG powder ,selective laser melting , imprinting in molds, thermoplastic shaping in the super-cooled temperature region. These methods are suitable for producing high value-added precision components but the problems still exists: expensive tools, limited lifetime of tools and the occurring of crystallization. Actually methods (thermoplastic shaping, casting and die forging) are limited by the low flexibility of production and by higher costs of tools and accessories. More suitable methods are greatly desired to machine MGs for their wider applications.

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Accessing thermoplastic processing windows in metallic glasses using rapid capacitive discharge

Cited by 40 publications

References 17 publications

Quantifying the origin of metallic glass formation

Quantifying the origin of metallic glass formation

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

An overview on the conventional and nonconventional methods for manufacturing the metallic glasses

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