Abstract: In this study, SiC/AA6061 composites with different SiC volume fractions (5%, 10%, 15% and 20%) were fabricated by spark plasma sintering. The deformation behaviour of the composites was studied by uniaxial compression test at temperatures from 573 K to 773 K and strain rates between 0.001 s^-1 and 1 s^-1. Results indicate that the flow stress of SiC/AA6061 composites increases with the increase of SiC volume fraction, with the decrease of deformation temperature and with the decrease of strain rate. The main deformation mechanism of the composites is dynamic recrystallisation (DRX), and the DRX degree depends on the processing parameters of deformation. Higher SiC volume fraction, higher deformation temperature and lower deformation strain rate promote the occurrence of DRX. The strain rate sensitivity and deformation activation energy of SiC/AA6061 composites are calculated. Results show that with the increase in deformation temperature and the decrease in SiC volume fraction, the strain rate sensitivity of the composites increases. From 573 K to 773 K, the average deformation activation energy of 5vol.%SiC/AA6061, 10vol.%SiC/AA6061, 15vol.%SiC/AA6061 and 20vol.%SiC/AA6061 are 207.91, 230.88, 237.7 and 249.87 kJ mol^-1, respectively. The optimum hot working zone of the SiC/AA6061 composites is in the temperature range of 723 K to 773 K at strain rates from 0.1 s^-1 to 1 s^-1.

Key words: Spark plasma sintering, Hot deformation, Al alloy matrix composites