Extrusion and heat treatment characteristics of 35% SiCp/6061Al composites

Silicon carbide particle (SiCp)-reinforced 6061 aluminum (SiCp/6061Al) composites were produced by vacuum hot-press sintering technology and were subjected to hot extrusion and T6 treatment. The microstructures of the composite materials were characterized by scanning electron microscopy and transmission electron microscopy. The density, tensile strength, hardness and conductivity of the composite materials were determined. The effects of hot extrusion and solution temperature on the microstructures and properties of SiCp/6061Al composites were investigated. The results show that hot extrusion can improve the microstructures and properties of the composite materials. After hot extrusion, the compact density improved from 98·09 to 99·10%, while the tensile strength was enhanced from 270 to 301 MPa. The properties of the composite materials can be further improved after T6 treatment. With increase in solution temperature, the dissolvable phases gradually mix and dissolve completely, with only a small quantity of insoluble phase remaining in the matrix, the hardness and tensile strength of composites first increase and then decrease, and the electrical conductivity decreases initially and attains stability after some time. After the solid is dissolved at 530°C and subjected to aging, the comprehensive property of SiCp/6061Al composite improves significantly. The tensile strength reaches 336 MPa, and the hardness is 101 HB.