3D nano-architected metallic glass: Size effect suppresses catastrophic failure

Abstract

We investigate the mechanical behavior of 3D periodically architected metallic glass nanolattices, constructed from hollow beams of sputtered Zr-Ni-Al metallic glass. Nanolattices composed of beams with different wall thicknesses are fabricated by varying the sputter deposition time, resulting in nanolattices with median wall thicknesses of ~88 nm, ~57 nm, ~38 nm, ~30 nm, ~20 nm, and ~10 nm. Uniaxial compression experiments conducted inside a scanning electron microscope reveal a transition from brittle, catastrophic failure in thickerwalled nanolattices (median wall thicknesses of ~88 and ~57 nm) to deformable, gradual, layerby-layer collapse in thinner-walled nanolattices (median wall thicknesses of ~38 nm and less).As the nanolattice wall thickness is varied, large differences in deformability are manifested through the severity of strain bursts, nanolattice recovery after compression, and in-situ images obtained during compression experiments. We explain the brittle-to-deformable transition that occurs as the nanolattice wall thickness decreases in terms of the "smaller is more deformable" material size effect that arises in nano-sized metallic glasses. This work demonstrates that the nano-induced failure-suppression size effect that emerges in small-scale metallic glasses can be proliferated to larger-scale materials by the virtue of architecting.

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