high velocity impact

The ability to transform the crystal structure of metals in the solid-state enables tailoring their physical, mechanical, electrical, thermal, and optical properties in unprecedented ways. We demonstrate a martensitic phase transformation from a face-centered-cubic (fcc) structure to a hexagonal-close-packed (hcp) structure that occurs in nanosecond timescale in initially near-defect-free single-crystal silver (Ag) microcubes impacted at supersonic velocities.

In an article published today in Science, we have demonstrated the creation of an extreme gradient-nano-grained (GNG) structure in single-crystal microcubes through high-velocity impact. We use the defect-free single-crystal silver microcubes, synthesized using a seed-growth process, as the model system, and fire them at supersonic velocities onto a rigid target to create the GNG structure.