The microstructure and mechanical properties of an Al–CuO in-situ composite produced using friction stir processing

Abstract Friction stir processing (FSP) was applied to produce aluminum based in situ composite from powder mixtures of Al–CuO. Fabricating the in-situ composite required combining the hot working nature of FSP and the exothermic reaction that occurs between aluminum and CuO. The reinforcements in the composite include nanometer-sized Al 2 O 3 and Al 2 Cu particles. These Al 2 O 3 nanoparticles were present in the form of clusters, which were identified as amorphous in the FSPed specimen. The average Al grain size in the FSPed composite was approximately 1 μm. The composite exhibited superior strength and ductility. The major contributions to the high strength of the composite are the ultrafine grained structure of aluminum matrix and the fine dispersion of nanometer-size reinforcing particles inside aluminum grains.