Abstract:Powder mixture of pure Al and oxidized SiC was consolidated into 10% (mass fraction) SiC_p/Al composites at 523 K by equal channel angular pressing and torsion (ECAP-T). The interfacial bonding of the composites was characterized by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The selected area electron diffraction (SAED) for the interface was investigated. The elements at the interface were scanned by energy dispersive spectroscopy (EDS) and the EDS mapping was also obtained. X-ray diffraction (XRD) analysis was carried out for the composites fabricated by 1 pass, 2 passes and 4 passes ECAP-T. According to the XRD analysis, the influences of ECAP-T pass on the Bragg angle and interplanar spacing for Al crystalline planes were studied. The results show that after ECAP-T, the interface between Al and SiC within the composites is a belt of amorphous SiO₂ containing a trace of Al, Si and C which diffused from the matrix and the reinforcement. With the growing ECAP-T pass, the Bragg angle decreases and interplanar spacing increases for Al crystalline planes, due to the accumulated lattice strain. The increasing lattice strain of Al grains also boosts the density of the dislocation within Al grains.

Key words: metal matrix composites; severe plastic deformation; interface; lattice strain; dislocation density