Fabrication and Deformation of Metallic Glass Micro-Lattices

Recent progress in micro‐ and nanofabrication techniques enables the creation of hierarchically architected microlattices with dimensional control over six orders of magnitude, from centimeters down to nanometers. This hierarchical control facilitates the exploration of opportunities to exploit nano...

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Bibliographic Details
Published in:Advanced engineering materials 2014-07, Vol.16 (7), p.889-896
Main Authors: Rys, Jan, Valdevit, Lorenzo, Schaedler, Tobias A., Jacobsen, Alan J., Carter, William B., Greer, Julia R.
Format: Article
Language:English
Subjects:
Amorphous materials
Deformation mechanisms
Ductile brittle transition
Fracture mechanics
Metallic glasses
Nanostructure
Structural materials
Wall thickness
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Summary:Recent progress in micro‐ and nanofabrication techniques enables the creation of hierarchically architected microlattices with dimensional control over six orders of magnitude, from centimeters down to nanometers. This hierarchical control facilitates the exploration of opportunities to exploit nano‐sized material effects in structural materials. In this work, we present the fabrication, characterization, and properties of hollow metallic glass NiP microlattices. The wall thicknesses, deposited by electroless plating, were varied from ≈60 nm up to 600 nm, resulting in relative densities spanning from 0.02 to 0.2%. Uniaxial quasi‐static compression tests revealed two different regimes in deformation: (i) Structures with a wall thickness above 150 nm failed by catastrophic failure at the nodes and fracture events at the struts, with significant micro‐cracking and (ii) Lattices whose wall thickness was below 150 nm failed initially via buckling followed by significant plastic deformation rather than by post‐elastic catastrophic fracture. This departure in deformation mechanism from brittle to deformable exhibited by the thin‐walled structures is discussed in the framework of brittle‐to‐ductile transition emergent in nano‐sized metallic glasses. This work presents the fabrication, characterization and properties of hollow metallic glass nickel‐phosphorous microlattices. We discovered that at wall thicknesses below ≈150nm the mechanical properties can no longer be calculated by classical models, with strengths nearly an order of magnitude higher than predicted. This is caused by a shift in deformation mechanism from post‐elastic catastrophic failure in thick‐walled structures to localized plastic deformability, which emerges as a result of brittle‐to‐ductile transition in nano‐sized metallic glasses. These findings suggest a viable and economic route to design and fabricate high‐strength, lightweight structural materials by combining structural effects with material size effects.
ISSN:1438-1656
1527-2648
DOI:10.1002/adem.201300454