Honeycomb Structures of Bulk Metallic Glasses

A combination of lithography and thermoplastic forming allows us to fabricate honeycombs from bulk metallic glass (BMG) precisely and to manipulate its structure selectively. Characteristics of the honeycomb such as the ligament length, thickness, and radius of curvature at the joints of the cells are varied to determine how changes in these characteristics affect properties under uniaxial in‐plane compression testing. It is found that the deformation behavior of BMG honeycombs can be controlled through microstructural design, from brittle to ductile, by changing the length to thickness ratio of the ligaments. The ability to absorb energy of BMG honeycombs exceeds honeycombs of most other materials due to the utilization of a size effect, which result in plasticity. Besides the usage for BMG honeycombs, the technique provides a general method to effectively characterize complex microstructural architectures and tailoring these architectures to the specifications of the material used.     

3D printing metals like thermoplastics: Fused filament fabrication of metallic glasses

Whereas 3D printing of thermoplastics is highly advanced and can readily create complex geometries, 3D printing of metals is still challenging and limited. The origin of this asymmetry in technological maturity is the continuous softening of thermoplastics with temperature into a readily formable state, which is absent in conventional metals. Unlike conventional metals, bulk metallic glasses (BMGs) demonstrate a supercooled liquid region and continuous softening upon heating, analogous to thermoplastics. Here we demonstrate that, in extension of this analogy, BMGs are also amenable to extrusion-based 3D printing through fused filament fabrication (FFF). When utilizing the BMGs’ supercooled liquid behavior, 3D printing can be realized under similar conditions to those in thermoplastics. Fully dense and amorphous BMG parts are 3D printed in ambient environmental conditions resulting in high-strength metal parts. Due to the similarity between FFF of thermoplastics and BMGs, this method may leverage the technology infrastructure built by the thermoplastic FFF community to rapidly realize and proliferate accessible and practical printing of metals.