Laser shock dynamic compaction of aluminum powder

Abstract

Dynamic compaction establishes shock waves that produces a violent dynamic mechanical response in powder. This process can realize the high-density compaction of powder to fabricate the compact of powder metallurgy parts with excellent performance. A new method for dynamic compaction of powder using laser shock on a small scale is proposed. It exhibits the unique advantages of a pulsed laser, such as high strain rate and dynamic shock force, and suitable for micro-part manufacturing. The experiment on the dynamic compaction of spherical aluminum powder was completed under five different laser energies. The effects of laser energy and powder packing state on the mechanical properties of the final compact and Microstructure of the compact, including the upper, failure, and cross section surfaces, were analyzed. Results showed that the mechanical properties of the aluminum compacts gradually improved with the increase of laser energy. The nearly fully dense aluminum compacts were successfully compressed at 1800 mJ laser energy with a final relative density of 99.72%. Moreover, the Microhardness of the compacts improved by approximately 60%. The simulation results using multi-particle finite element method (MPFEM) show that with the propagation of the generated shock wave in the compact, particles had large plastic deformation that filled the pores during the laser shock dynamic compaction of aluminum powder. The simulation and experimental results show that the main connection mechanism of particles is cold welding. The dense packing of powder before compaction could considerably improve the propagation of shock waves, and the initiation and growth of inter-particle cracks were reduced.