Preparation of SiCp/Al–Si composites

In this study, billets of silicon carbide particle (SiCp)/aluminum (Al)–silicon (Si) composites were prepared by the one-way press method. The cold billets were sintered in nitrogen atmosphere and hot extruded. The effect of different holding pressures and holding times and the duration of different applied pressure on cold-press billet were studied. Moreover, the influence of the different extrusion ratios and extrusion speeds on the composite bars was studied. The microstructure and tensile strength of materials were affected by the heat treatment temperature. The composites were characterized by scanning electron microscopy and tensile stress measurements. Results show that the cold-press billet is most intact when it is pressed at 500 MPa for 30 min and incubated for 30 min. In the process of hot extrusion, the surface of composite bar is smoothest when the extrusion temperature, ratio and speed are, respectively, 480°C, 15:1 and 1 mm/s. Compared with cold-press billet, the density of the composite is increased significantly from 78·84 to 98·86% after hot extrusion. As solid solute at 500°C for 4 h and then aging at 190°C for 6 h, the tensile strength of the composite is best, reaching up to 280·42 MPa.