Processing Route Optimization and Characterization of Al6063–SiCp Metal-Matrix Composite Sheets

Abstract

The target of this study is to develop routes for processing Al–SiCp (SiC particulate) sheets with improved microstructures; namely, the uniform distribution of SiCp and minimized porosity throughout the whole material, thereby improving its mechanical properties. Al–SiCp composites reinforced with 5, 10, and 15 vol.% SiC and having three average sizes of 29, 17, and 8.5 µm were produced using a semi-automated stir-casting machine; finally, the bars were hot rolled to get the final sheet dimensions. The rolling steps were performed based on the results of thermomechanical simulations performed on the cast blocks. The first rolling steps were applied according to a safe rolling schedule to avoid cracking via encouraging dynamic recrystallization. The last rolling steps were performed to improve the hardness and strength of the metal matrix composites (MMCs). A refinement in grain size from an average of 420 µm in the as-cast condition to an average of about 85 µm after rolling was observed. Some heterogeneity in grain size was observed where the regions with larger, elongated grains were associated with the zones depleted by SiCp reinforcement. Reinforcing with SiCp led to a small increase in tensile strength of 10–20 MPa, and this was further improved to about 60 MPa and 110 MPa for the 5 and 10 vol.% SiCp conditions, respectively, after a T6 heat treatment.

Keywords

• Al–SiC composites
• stir casting
• thermomechanical simulation
• dynamic recrystallization
• hot rolling
• tensile properties