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

Abstract

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.