Effects of Al Content on the Physical Properties of Al₂O₃ Dispersion-Strengthened Copper Alloys

Abstract

Based on three kinds of CuAl alloy powders with Al mass fraction of 0.18, 0.55 and 1.95%, respectively, as raw materials and Cu₂O powder as oxidant, three dispersion-strengthened copper alloy powders with Al₂O₃ content of 0.34, 1.00 and 3.19%, respectively, were prepared by internal oxidation using the optimal internal oxidation parameter. Hot pressing was subsequently adopted to prepare Al₂O₃ dispersion-strengthened copper (Cu–Al₂O₃) alloys. The effects of Al₂O₃ content on microstructures and properties of alloy powders and sintered alloys were studied. The results showed that the microhardness of three alloy powders after internal oxidation was significantly improved and increased with increasing Al₂O₃ content. But the difference between powders with 1.00 and 3.19% Al₂O₃ content was small. The relative densities of sintered alloys with lower Al₂O₃ content, i.e. 0.34 and 1.00%, were both above 99%. However that with higher Al₂O₃ content, i.e. 3.19%, was only 97.8%. With increasing Al₂O₃ content, electrical conductivity decreased and hardness increased obviously. The electrical conductivity and hardness (HRB) of three alloys were 86.0, 71.5, 60.0% IACS, and 68.8, 84.3, 91.0, respectively.