Co-continuous silica–aluminum composite

In this work, a metal matrix composite Al–5SiO2 was produced using fossil silica fibers spikes as reinforcement. After being heat-treated at 600 °C, the original fiber morphology was retained but its microstructure has changed from solid silica to the interconnected Al–Al2O3 interlaced phases known as co-continuous structure. Powder metallurgy, using commercial aluminum powder and the silica fibers as starting materials, followed by hot extrusion were used to produce the composite. The co-continuous microstructure was obtained partially or totally on the fibers as the result of the reduction reaction, which occurs during the heat treatment, by solid diffusion and by the liquid Al–Si alloy, in local equilibrium, produced by the silicon released during the reaction. The internal structure of the fibers was characterized on polished and fractured samples using SEM and optical microscopy. The heat-treated samples were submitted to uniaxial tensile tests and the results were compared with results obtained from annealed and original work-hardened conditions. Microstructure analyses and tensile tests showed a strong interfacial bonding between the fibers and the matrix in the heat-treated extruded samples, justifying the higher UTS obtained, compared with work-hardened and annealed conditions.