Mechanical Properties of Nanometric Al<SUB>2</SUB>O<SUB>3</SUB> Particulate-Reinforced Al-Al<SUB>11</SUB>Ce<SUB>3</SUB> Composites Produced by Friction Stir Processing

Abstract

Aluminum matrix composites reinforced with nanometer sized Al2O3 particles were produced from powder mixtures of Al and CeO2 by the use of friction stir processing (FSP). This approach has combined hot working nature of FSP and exothermic reaction between Al and oxide. In the composites, Al2O3 particles (∼10 nm in size) and Al11Ce3 intermetallic compound were formed in situ by oxide-aluminum displacement reaction. The aluminum matrix of the composites has an average grain size about 400 nm. The composites produced exhibit high strength both at ambient and elevated temperatures. It is mainly attributed to the uniform dispersion of nanometer sized Al2O3 particles, which not only contribute significantly to the strength by the Orowan mechanism but also stabilize the fine structure at elevated temperatures.