Study on the behavior of randomly distributed Al-Cu nanopowders by laser shock dynamic compaction

To address the unique challenges presented by the dynamic compaction of realistically distributed nanopowders under laser shock, which differs from the compaction process of regularly arranged powders. A study investigates the laser shock dynamic compaction (LSDC) behavior of randomly distributed nano Al-Cu powders. The aim was to investigate the microstructural evolution and densification of randomly distributed nano Al-Cu powders during LSDC and to assess the effect of varying nano Cu content on the density and mechanical properties of Al-Cu nanopowder compacts. Using a self-developed LSDC platform, nano aluminum and nano copper powders were uniformly mixed in mass ratios of 5 %, 10 %, and 15 %, producing compacts with a density of 95.36 %. A model was established via the Gurney energy equation to link laser energy to upper punch velocity, and the compaction response of the nanopowders at different velocities was simulated. Molecular dynamics (MD) modeling, constructed using Atomsk and LAMMPS software, closely represented actual conditions, allowing characterization of crystal structure changes, dislocation evolution, and other behaviors during laser shock compaction. Results indicated that increasing nano Cu content led to a gradual decrease in the microhardness of Al-Cu compacts. Across shock velocities from 500 to 1500 m/s, the material exhibited three stages: solid non-densification, solid densification, and liquid densification. The study quantified temperature distribution and dislocation density during laser shock, clarifying compaction mechanisms at various shock velocities. These findings reveal the microstructural evolution, temperature distribution, and densification processes in the laser dynamic compaction of randomly distributed nano Al-Cu powders, providing theoretical support for LSDC technology applications in nanomaterial development.