Laser shocking of nanocrystalline materials: Revealing the extreme pressure effects on the microstructural stability and deformation response

Abstract

We present the first results of laser-driven flyer plate experiments on a nanocrystalline copper-tantalum (NC–Cu–Ta) alloy. A pulsed Nd:YAG laser (1.2 J/pulse, 10 ns) is used to accelerate an Al foil disk (25 μm × ∼800 μm) off a glass substrate at velocities of 0.8 and 2.4 km/s through a small air gap and impact the NC–Cu–Ta target. The flyer velocities were determined from a high-speed video and extensive post-impact analyses were conducted using advanced electron microscopy revealing the formation of a band structure leading to a non-trivial upper bound for the breakdown of an extremely stable NC-microstructure and physical-properties.