Precipitated Al2O3 phase characterization in internally oxidized Cu-Al alloy sheets

Cu-Al2O3 composite sheets were prepared by Cu-Al alloy sheet internal oxidation. The Al2O3 precipitation phase was extracted from the Cu-Al2O3 composite sheets. The Cu-Al2O3 composite sheets were melted and then solidified to prepare Cu-Al2O3 bulk composite ingot. The crystal types and distribution of precipitated Al2O3 phase in the Cu-Al2O3 composite sheets and the ingot were investigated. In the Cu-Al2O3 composite sheet, the crystal types of the Al2O3 precipitation phase include γ-Al2O3, α-Al2O3 and θ-Al2O3. The main γ-Al2O3 phase has a coherent interface with the Cu matrix, and the amount of α-Al2O3 and θ-Al2O3 phases decreases from the surface to the bulk. During composite sheets melting, dispersed Al2O3 particles aggregated, and became isolated from the Cu matrix. Most of the γ-Al2O3 phase was transformed into the α-Al2O3 phase.