The Effect of Pre-compaction on Dynamic Compaction Process of Al/SiCNanocomposite Powder

The effect of quasi-static pre-compaction on the mechanical and microstructural properties of Al7075/SiC and Al6061/SiC nanocomposites fabricated by dynamic compaction is investigated in this study. The increase in initial density by quasi-static pre-compaction plays an important role on properties of dynamic compacted metal powders. Pre-compaction is a useful operation in high velocitycompaction (strain rates 105s-1 to 107s-1) which can improve the green density of final compacted sample. However, it is shown in this work that pre-compaction of powder followed by lower strain rates compaction process (101s-1 to 103s-1)may lead to lower density, hardness, and even strength of the compacts. Damage and embrittlement were observed almost in all of the samples compacted initially before dynamic compaction. Investigations show that intensive cold work on pre-compacted samples may be one of the reasons of lower densification. Also, less free space between particles in precompacted specimens which may result in lower particles velocity and weaker bonding is believed tobe another affecting factor.

Keywords:

Nanocomposite , dynamic compaction , pre-compaction , Al7075 , Al6061 , SiC nanoparticle