Effect of plastic deformation treatment on microstructure and comprehensive properties of SiCw reinforced 2000 series aluminium matrix composites

SiC whisker (SiCw) reinforced 2000 series aluminium matrix composites (AMCs) with superior strength of 500 MPa were successfully prepared by traditional powder metallurgy, plastic deformation and heat treatment. The effect of plastic deformation treatment on their microstructure and comprehensive properties were investigated using an optical microscope (OM), scanning electron microscope (SEM) and its equipped energy dispersive spectrometer (EDS), respectively. The phases and contribution of dislocation strengthening were analysed using an X-ray diffraction (XRD). The results showed that the secondary extrusion had the best effect on the grain refinement and dispersing reinforcement; and the forging also increased the number of equiaxed grains, which failed to completely eliminate the pore defects. The relative density of primary extruded AMC was 98.05%, which was improved after the secondary extrusion and forging by 1.46 and 1.07%, respectively. Compared with the primary extruded AMC, the electrical conductivity was reduced by 3.47% after the secondary extrusion and increased by 8.40% after the forging. On the basis of primary extruded AMC, the secondary extrusion increased the hardness, tensile strength and elongation by 14.16, 6.15, and 6.67%, respectively; while the forging slightly decreased the hardness, tensile strength and elongation by 3.15, 2.85, and 6.67%, respectively.