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Two types of Mg-Cu composition system graded density impactors used for complex loading (shock loading and quasi-isentropic compression) are designed by the elastic-plastic hydrodynamic method in this paper. Mixtures of metal powders in the Mg-Cu system are cast into a series of 17 and 25 uniform compositions ranging from 100% Mg to 100% Cu. The graded density impactors are launched to the stationary 10 μm aluminum film and 12 mm LiF window targets by a two-stage light-gas gun in the National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, CAEP, and the resulting wave profiles are measured with the DISAR system. Hydrodynamic simulation results are perfectly consistent with the experiments. Our work in this paper will set up a foundation for further research of controllable loading/releasing routes and rate experiments in the future.

We designed an Mg-W functionally graded-density materials system with two different sequences of density–thickness distributions and fabricated disk-like pellets with the graded-density materials by elaborate stacking of different metal powder layers, followed by a one-step hot-pressure sintering process. The microstructures of the sintered pellets were characterized using a scanning electronic microscope and a scanning acoustic microscope. The pellets were used as graded-density impactors (GDIs) to test their capabilities to produce complex particle-velocity wave profiles along a specified thermodynamic path. The wave profile was obtained from reverse-impact experiments using a two-stage light gas gun in which the GDI flyer impacted a lithium fluoride window. The particle-velocity history at the impact surface of the LiF window was deduced from the interference fringe numbers of the distance interferometer system for any reflector records. For GDIs consisting of nine composition layers of graded-density materials, the particle velocity profiles displayed combined shock loading and quasi-isentropic compressing and release processes. The impactor, consisting of 12 composition layers, produced wave profiles that contained shock loading, quasi-isentropic reloading, controlled releasing, and recompressing and released processes. The wave profiles simulated using a hydrodynamic computer model developed in house agree well with the experimental results as well as other theoretical results.