Correlation of Fine Scale Microstructure and Mechanical Properties of Copper-Alumina Nanocomposites

Considerable efforts have been made to manufacture metal matrix composites (MMCs) in the solid state to enhance the mechanical properties by adding various volume fractions of alumina powder to achieve higher homogeneity of ceramic particles in the matrix. Here, we present the fine scale microstructure, interfacial characteristics and mechanical properties of the copper-alumina composite. The fine scale microstructure was characterized by transmission electron microscopy (TEM) to study the nature of oxide precipitates formed during internal oxidation of copper–aluminum alloy. We used nanoindentation to obtain the hardness and modulus of the composite and demonstrated that the enhancement of strength mostly stems from the nanocrystalline oxide particles. Furthermore, we observed that the elastic modulus of the composite is 15% greater that of the commercially pure copper. The improvement in modulus is shown to be associated with the formation of nanocrystalline coper oxide (Cu₂O) or copper–oxygen (Cu–O) clusters in copper matrix.