Processing of ultra-high strength SiCp/Al-Zn-Mg-Cu composites

The ultra-high strength SiCp/Al-10%Zn-3.6%Mg-1.8%Cu-0.36%Zr-0.15%Ni composite was prepared by spray co-deposition followed by extrusion process. The heat treatment processing, microstructures and mechanical properties of the as-processed composite were investigated. The well-bonded SiC/Al interfaces and fine grains of matrix alloy were obtained in the as-extruded composite. The precipitated phase MgZn2 dissolved during solid solution treatment at 490 degrees C for 1 h, but the Cu-rich phase was residual in the matrix. Comparatively, the Cu-rich phase dissolved into the matrix alloy exposed at 470 degrees C for 1 h and then at 490 degrees C for 1 h. The composite heat-treated with 470 degrees C/1 h + 490 degrees C/1 h + 120 degrees C/28 h exhibited high modulus above 100 GPa and ultra-high strength about 785 MPa, which was 30 MPa higher than that of the same composite treated with 490 degrees C/1 h + 120 degrees C/28h processing. The low elongation of the composite can be attributed to the breakage of SiC particulates and interfacial debonding of SiC/Al. (C) 2008 Elsevier B.V. All rights reserved.