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.

Highlights

  • Laser-driven flyer plates, produced by laser-plasma acceleration of thin metal foils adhered to a glass substrate, could be a method to access such extreme regimes in NC materials, along with any transition in the deformation mode

  • We present the first results of laser-driven flyer plate experiments on a nanocrystalline copper-tantalum (NC–Cu–Ta) alloy

  • 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

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Summary

Introduction

Laser-driven flyer plates, produced by laser-plasma acceleration of thin metal foils adhered to a glass substrate, could be a method to access such extreme regimes in NC materials, along with any transition in the deformation mode (slip vs twining). It has been previously determined that such nanoclusters play an important role in dictating the mechanical response as well as stabilizing the matrix grain size under the application of stress and temperature, such as during processing and high rate mechanical testing.9,13,16 To evaluate microstructural stability under extreme rates, the NC–Cu–3Ta (at.%) disks were impacted by laser-driven flyer plates at 0.8 km/s ($9 GPa shock pressure) and 2.4 km/s ($34 GPa shock pressure).

Results
Conclusion

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