Effect of Punch Shape on Dynamic Compacted Powders

In the present study, the thin film forming of pure aluminum powders is carried out by a dynamic compaction method. The influence of processing parameters on the density, mechanical properties and microstructures of compacted powders is investigated. The control of stress wave is also attempted in order to obtain a high compacting stress due to the superimpose of stress waves. The dynamic powder compaction is carried out by an electromagnetic induction method. This method allows easy control of stress pulse. Two kinds of punches with a straight shape and a sudden increase in cross section are used for the dynamic powder compaction. Pure Al powders of 37 mu m in average are used as a raw material for the compaction. The compactions are carried out at room temperature in air. A density measurement shows that the compacted Al powders have a relative density of 0.90-0.97. As the stress has increased with a superimpose of the incidence stress wave and reflection stress wave in using the punch with the sudden increase in cross section, the bending strength of the compacted powders is stronger than the one in using the punch with a straight shape.