High aspect ratio micro mechanical structures made of bulk metallic glass

Geometrically complex, high aspect ratio microstructures and limited aspect ratio nanostructures have been successfully fabricated in supercooled Bulk Metallic Glass (BMG) substrates by molding against patterned Silicon and Silicon dioxide substrates. However, demand exists for similar metallic substrates with high aspect ratio, nanoscale features. Van Der Waals based interfacial energies between the supercooled liquid BMG and the Silicon cavity represent a substantial obstacle to the direct scaling of the molding process to the nanoscale. In an effort to investigate these effects, experiments were conducted using molds of various compositions: Silicon, SiO2 and SiO2 coated with Gold. The Gold coating failed to impact molding performance due to the thin layer deposited. However, drastically superior results were obtained by using a Silicon mold because of the variation in interfacial interaction between the BMG and the mold material. In addition, a theoretical model to predict achievable aspect ratio is presented and was found to be in qualitative agreement with experimental results. Finally, a value for the surface tension of Viterloy-1b within it’s supercooled liquid state was deduced from experimental data.

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Thin Film Superplastic Forming Model for Nanoscale Bulk Metallic Glass Forming

Volume 4: Design and Manufacturing ◽

10.1115/imece2008-68759 ◽

2008 ◽

Author(s):

Catherine Mros ◽

Kavic Rason ◽

Brad Kinsey

Keyword(s):

Thin Film ◽

Aspect Ratio ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

High Aspect Ratio ◽

Process Model ◽

Flow Model ◽

Superplastic Forming ◽

Viscous Term ◽

Aspect Ratios

Geometrically complex, high aspect ratio microstructures have been successfully formed in Bulk Metallic Glass (BMG) via superplastic forming against silicon dies [1–3]. Although nanoscale features have been created in a similar fashion, there exists a demand to develop these metallic nanofeatures into high aspect ratio nanostructures with controlled geometries. In past research a process model was created to predict the achievable nanoscale feature sizes and aspect ratios through a flow model [4]. The flow model assumes force equilibrium with a viscous term to account for the required force to produce flow and a capillary pressure term required to overcome surface effects which are significant at the nanoscale. In this paper, a thin film model to predict the pressure distribution across the BMG during the forming process when it is in the supercooled liquid state is presented. Silicon molds with various nanofeatures were produced using Deep Reactive Ion Etching to achieve high aspect ratio dies over a relatively large area in order to validate these models.

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Preparation of high aspect ratio surface microstructures out of a Zr-based bulk metallic glass

Microelectronic Engineering ◽

10.1016/s0167-9317(03)00096-0 ◽

2003 ◽

Vol 67-68 ◽

pp. 405-409 ◽

Cited By ~ 21

Author(s):

A.A. Kündig ◽

M. Cucinelli ◽

P.J. Uggowitzer ◽

A. Dommann

Keyword(s):

Aspect Ratio ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

High Aspect Ratio ◽

Surface Microstructures

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Compressive properties of bulk metallic glass with small aspect ratio

Journal of Materials Research ◽

10.1557/jmr.2007.0064 ◽

2007 ◽

Vol 22 (2) ◽

pp. 501-507 ◽

Cited By ~ 34

Author(s):

F.F. Wu ◽

Z.F. Zhang ◽

S.X. Mao

Keyword(s):

Plastic Deformation ◽

Aspect Ratio ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

Deformation Behavior ◽

Shear Bands ◽

Compressive Load ◽

Small Aspect Ratio ◽

Compressive Properties ◽

Deformation Ability

The quasi-static compressive deformation behavior of a Vitreloy 1 bulk metallic glass (BMG) with an aspect ratio of 0.25 was investigated. It is found that the friction and the confinement at the specimen–loading platen interface will cause the dramatic increase in the compressive load, leading to higher compressive strength. In particular, the BMG specimens show great plastic-deformation ability, and plenty of interacted, deflected, wavy, or branched shear bands were observed on the surfaces after plastic deformation. The formation of the strongly interacted, deflected, wavy, or branched shear bands can be attributed to the triaxial stress state in the glassy specimens with a very small aspect ratio.

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High aspect ratio grating by isochronal imprinting of less viscous workable Gd-based metallic glass for neutron phase imaging

Intermetallics ◽

10.1016/j.intermet.2016.09.004 ◽

2016 ◽

Vol 78 ◽

pp. 55-63 ◽

Cited By ~ 7

Author(s):

Maryam Sadeghilaridjani ◽

Kosuke Kato ◽

Takenao Shinohara ◽

Wataru Yashiro ◽

Atsushi Momose ◽

...

Keyword(s):

Aspect Ratio ◽

Metallic Glass ◽

High Aspect Ratio ◽

Phase Imaging

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The more shearing, the thicker shear band and heat-affected zone in bulk metallic glass

Journal of Materials Research ◽

10.1557/jmr.2008.0258 ◽

2008 ◽

Vol 23 (8) ◽

pp. 2133-2138 ◽

Cited By ~ 16

Author(s):

H. Guo ◽

J. Wen ◽

N.M. Xiao ◽

Z.F. Zhang ◽

M.L. Sui

Keyword(s):

Aspect Ratio ◽

Shear Band ◽

Metallic Glass ◽

Shear Deformation ◽

Bulk Metallic Glass ◽

Heat Affected Zone ◽

Shear Bands ◽

Source Model ◽

Ion Milling ◽

Low Aspect Ratio

In a compression test for a Zr-based bulk metallic glass, a dominant shear band was preserved before fracture by a cylindrical stopper. A heat-affected zone (HAZ) ∼10 μm thick together with shear band was discovered in the center of the deformed sample by preferential ion milling. By using a low aspect ratio sample for compression, diverse micron-scaled HAZs among multiple shear bands were also revealed. Based on above experimental results and the isothermal source model, it was found that the thickness of shear band and its HAZ increased continuously with the progression of shear deformation.

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Geometry-sensitive plasticity of a monolithic bulk metallic glass

MRS Proceedings ◽

10.1557/proc-1048-z05-06 ◽

2007 ◽

Vol 1048 ◽

Author(s):

WenFei Wu ◽

Yi Li

Keyword(s):

Aspect Ratio ◽

Plastic Strain ◽

Metallic Glass ◽

Bulk Metallic Glass ◽

New Method ◽

Catastrophic Failure ◽

Sample Geometry ◽

Glassy Alloys ◽

Geometry Dependence ◽

Orthogonal Geometry

AbstractWe report a strong geometry-dependence of compressive plasticity in a Zr-based bulk metallic glass (BMG). With a standard orthogonal geometry, the Zr-based BMG typically fractured at a plastic strain less than 2%. However, by modifying the sample geometry while maintaining the sample aspect ratio, a large apparent compressive plastic strain over 10% was achieved consistently. These results present a new method on arresting the catastrophic failure of the glassy alloys and offer ways for BMGs in engineering applications.

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