Plasticity in small-sized metallic systems: Intrinsic versus extrinsic size effect

Mechanical behavior of high-entropy alloys

Overview on micro- and nanomechanical testing: New insights in interface plasticity and fracture at small length scales

Mechanistic investigation of a low-alloy Mg–Ca-based extrusion alloy with high strength–ductility synergy

We report the synthesis, mechanical properties, and deformation mechanisms of polycrystalline, platinum nanocylinders of grain size d = 12 nm. The number of grains across the diameter, D/d, was varied from 5 to 80 and 1.5 to 5 in the experiments and molecular dynamics simulations, respectively. An abrupt weakening is observed at a small D/d, while the strengths of large nanopillars are similar to bulk. This “smaller is weaker” trend is opposite to the “smaller is stronger” size effect in single crystalline nanostructures. The simulations demonstrate that the size-dependent behavior is associated with the distinct deformation mechanisms operative in interior versus surface grains.

/pdf/size-dependent-deformation-of-nanocrystalline-pt-nanopillars-32wwvg9l1o.pdf

Size-Dependent Deformation of Nanocrystalline Pt Nanopillars

Size effects in Al nanopillars: Single crystalline vs. bicrystalline

The threat of micro-meteoroid and orbital debris (MMOD) collisions with spacecraft and satellites has been increasing with the increasing worldwide use of low earth orbit. Providing low-areal-density shielding for the mitigation of these high velocity impacts is essential for ensuring successful and cost effective missions. Here, we report results obtained from hypervelocity impact testing on bulk metallic glass (BMG) matrix composites. Their carbide-like hardness, low melting temperatures, ultra-high strength-to-weight ratio and the ability to be processed like polymers are material attributes ideally suited for spacecraft shielding, particularly as an outer wall bumper shield.

Allison Kunz

Papers

Size effects in Al nanopillars: Single crystalline vs. bicrystalline

Investigating Amorphous Metal Composite Architectures as Spacecraft Shielding

Continuum modeling of dislocation starvation and subsequent nucleation in nano-pillar compressions