Experimental study on dynamic response of micron aluminum powder.

It is important to investigate the dynamic compression of granular materials, owing to their extensive applications in powder metallurgy, material processing, and ammunition engineering. This study investigates the dynamic compression behavior of micron-sized Al powders under various loading conditions using a split-Hopkinson pressure bar. We record the development of the speckle field and measure the surface temperature of the Al powder specimen during dynamic loading using a high-speed camera and an infrared temperature measurement system, respectively. Additionally, we compare the morphology of the specimens subject to different loadings using scanning electron microscopy after the test. Our results show that the temperature of the Al powder specimen continued to increase after loading, which is different from that of solid materials. The result indicates that there were interactions between particles when impact pulse ended. It was also observed that after the confined loading, there was no melting between particles. However, in the unconfined cases, particles melted and merged, which occurred because the friction between particles is violent. Thus, heat generation is not significant when the radial motion is restricted. Finally, we observed that there was a small amount of particles melting phenomenon after single-pulse loading, owing to insufficient impact energy and the small deformation of particles. However, in cases with multiple impacts without lateral constraints, the particles melted and formed dense Al blocks. Our work defines the sintering mechanism of Al powder and paves the way for related applications. [ABSTRACT FROM AUTHOR]