Dynamic compaction of nickel nanopowders: Experiment and MD simulation using the laser shock method

Abstract

In this paper, a method of dynamic compaction of nanopowders by laser shock is proposed, which is suitable for the compaction of micro-parts with the advantage of high strain rate and controllability. The effect of pre-pressure and laser energy on the mechanical properties and microstructural characteristics of nickel compacts were analysed experimentally. The results indicate a progressive improvement in the mechanical properties of nickel billets with increasing prepressure and laser energy. Notably, under the prepressure of 3 GPa and laser energy of 1.8 J, dense nickel compacts were achieved with the relative density of 94.45% and the microhardness of 170–240 Hv. Molecular dynamics simulation reveals that at a certain pressure threshold, plastic deformation, lattice modification, and dislocation slip occur among nanoparticles, causing strain hardening and a gradual increase in relative density. Furthermore, nanoparticle size inversely correlates with the compaction pressure. The main bonding mechanism of particles is cold welding.