Compaction behavior of Al6061 and SiC binary powder mixture in the mushy state

• Compaction of Al6061–SiC powder mixture in the semi-solid state was studied for the first time.
• Compaction mechanism of binary powder system was identified for various conditions.
• Overall compaction behavior was similar regardless of hard phase amount at a given liquid fraction.

Synthesis of ceramic particle reinforced metal composites in the semi-solid state enables fabrication of fully dense composites at relatively low pressures. Only limited study, however, has been found on the compaction behavior and mechanism of the ceramic-metal, binary powder system in the semi-solid state. In this study, the effects of silicon carbide (SiC) volume fraction (0–60%) and aluminum alloy 6061 (Al6061) liquid fraction (0–100%) on the compaction behavior of Al6061–SiC binary powder mixture were investigated. The results showed that the Al6061 liquid fraction significantly influenced the liquid factor (KL), reinforcement factor (KH), and final density of the powder compact. The liquid factor decreased exponentially as the liquid fraction of Al6061 increased. Higher liquid content can weaken the powder structure and lower the reinforcement factor. On the other hand, excessive amount of liquid will lower the final density because of the squeeze out of the liquid from the die. A full density, Al6061–50 vol.% SiC composite can be obtained with 150 MPa compaction pressure when the liquid fraction is between 25% and 40%.