Fabrication and Deformation of Metallic Glass Micro-Lattices

Authors


  • The authors gratefully acknowledge the financial support of DARPA through the Materials with Controlled Microstructural Architecture program and of JRG's NASA Early Career grants. The authors are grateful to Ramathasan Thevamaran and Ladan Salari for helping on bulk compression testing, Scott Godfrey for FE simulations, Lucas Meza and Dongchan Jang for fruitful discussions and the Kavli Nanoscience Institute (KNI) at Caltech for providing support and infrastructure.

Abstract

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.

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