Fabrication of Al6061 composite with high SiC particle loading by semi-solid powder processing

Aluminum alloys reinforced with silicon carbide (SiC) particles have been studied extensively for their favorable properties in structural and thermal applications. However, there has been only limited research into investigating the loading limit of a reinforcement phase of a metal matrix composite. In this paper, semi-solid powder processing (SPP), a fabrication method that exploits the unique behavior of a solid–liquid mixture, was used to synthesize SiC particle-reinforced Al6061. A high volume loading (>45 vol.%) of SiC in Al6061 matrix was investigated by varying the SiC loading volume fraction, forming pressure, SiC particle size and Al6061 particle size. The compaction and synthesis mechanism of the composite by SPP was discussed based on reinforcement phase compaction behavior and processing parameters. Microstructure, hardness, fracture surface and X-ray diffraction results were also analyzed. Results showed that SPP can achieve over 50 vol.% loading of SiC in Al6061 matrix with near theoretical density.