Warm dynamic compaction of Al6061/SiC nanocomposite powders

Abstract

Powder dynamic compaction is one of the new methods for the production of nanocomposites. In this paper, Al6061/SiCnp nanocomposite is compacted using warm dynamic compaction by simultaneous application of heat and dynamic compressive waves. A comparison between the results of this study and those reported in the literature confirms that the warm dynamic compaction methods are superior to cold dynamic and quasi-static compaction method in densification of nanocomposites especially for high volume fractions of nano particles reinforcement. Mechanical and microstructural characterization of the samples is carried out to investigate the effects of temperature and content level of reinforcement. The results indicate that the increase of nano reinforcement content in warm dynamic compaction leads to reduction of the relative density and increase of hardness and the compressive strength. Moreover, higher compaction temperatures result in enhanced density and lower hardness. It is shown that samples compacted using warm dynamic compaction exhibit lower spring back and ejection force and also the distribution of mechanical properties is significantly more homogeneous. Sensitivity analysis showed that temperature increase has the most effect on homogeneity improvement and reducing dimensional change. Microscopic analyses verified that higher compaction temperature leads to lower porosity and improved metal particle bonding. It seems that agglomeration of nanoparticles and destructive phenomena such as capping and delamination are the main reasons for loss of compressive strength at room temperature. These issues are resolved in warm dynamic compaction by increasing the compaction temperature which leads to better bonding between particles.