TiO2 ceramic particles-reinforced aluminum matrix composite prepared by conventional, microwave, and spark plasma sintering

Aluminum-10wt% TiO2 metal matrix composites were fabricated with conventional, microwave, and spark plasma sintering processes. Aluminum and nano-sized TiO2 powders were mixed using a high-energy mixer, and the sintering process was done at 450? by spark plasma sintering and 600? under both microwave and conventional heating. The results showed microwave sintering led to form Al3Ti intermetallic compounds with flaky shape, while in the conventional heating at the same sintering temperature, Al3Ti was formed and confirmed by X-ray diffraction and scanning electron microscope investigations. Moreover, the nano-sized TiO2 particles as reinforcement with no additional phase were obtained by spark plasma sintering at the lowest sintering temperature. The maximum bending strength of 254 +/- 12MPa and Vickers hardness of 235 +/- 13 were measured for samples sintered in microwave as a consequence of Al3Ti formation. The SEM and energy-dispersive X-ray spectroscopy analyses showed uniform distribution of Al3Ti particles in the microstructure of microwave sintered samples and nonuniform distribution of agglomerated Al3Ti particles and porosities in samples sintered by spark plasma sintering and conventional heating.