Comparison study on the annealing behaviors of dispersion strengthened copper alloys with different nanoparticles

Abstract

The hardness measurement, optical microscopy (OM), and transmission electron microscopy (TEM) microstructure observation on the annealing behaviors of Cu-Al 2O 3 (2.25 vol.% and 0.54 vol.% Al 2O 3) and Cu-0.52vol.%Nb alloys were carried out. The results show that with the increase of annealing temperature, the hardness of Cu-Al 2O 3 alloys decreases slowly. No change of the fiber structure formed by cold rolling in the Cu-2.25vol.%Al 2O 3 alloy is observed even after annealing at 900°C, and the higher dislocation density can still be observed by TEM. Less combination of fiber formed by cold rolling and subgrains are observed in the Cu-0.54vol.%Al 2O 3 alloy annealed at 900°C. With the increase of annealing temperature, the hardness of the Cu-0.52vol.%Nb alloy exhibits a general decreasing trend, and its falling rate is higher than that of the Cu-Al 2O 3 alloys, indicating that its ability of resistance to softening at elevated temperature is weaker than that of the Cu-Al 2O 3 alloys. However, when annealed at a temperature of 300–400°C, probably owing to the precipitation strengthening of niobium, the hardness of the Cu-0.52vol.%Nb alloy arises slightly. The fibers formed by cold rolling become un-clear and un-straight and have less combination, and considerably more subgrains are observed by TEM.