Spark plasma sintering ( SPS ) is a sintering technique utilizing uniaxial force and a pulsed direct current to perform metallic or ceramic particles consolidation in very short times. The high heating and cooling rates allow to prevent excessive grain growth favoring densification. Spark Plasma Sintering has been recognized, in the recent past, as a very useful method to produce metal matrix composites with enhanced mechanical and wear properties. Obviously, the materials final properties are strongly related to the reinforcement types and percentages as well as to the processing parameters employed during synthesis. The present paper analyses the effect of microscopic and nanometric alumina particles, blended to pure aluminum in different combinations, on the final properties of metal matrix composites produced via . The ed composites were friction stir processed (FSWed), the processing forces and the heat input in the materials were analyzed. The microstructural and mechanical behavior of the processed materials is shown to be strongly dependent on the starting materials properties and on the employed processing parameters during FSW.