Enhanced strength of a high-conductivity Cu-Cr alloy by Sc addition

A new Cu-Cr-Sc alloy was designed, prepared and subjected to deformation heat treatment. Transmission electron microscopy (TEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) were employed to investigate the effects of Sc on the microstructural changes in the Cu-Cr alloy in different states, examine the changes in the precipitates during aging, reveal the intrinsic correlation between the structure and property in the peak aging state, and evaluate the Sc distribution in the Cu-Cr alloy. The addition of Sc significantly increased the yield strength of the Cu-Cr alloy by ~ 24.6% after aging at 480 °C for 1 h, while it had a high electrical conductivity of 81.5% international annealed copper standard (IACS). This enhancement was attributed to the effective inhibition of Cr phase coarsening and recrystallization through the addition of Sc, which strengthened the alloy. Furthermore, in the Cu-Cr-Sc alloy, most of the Sc atoms precipitated as the Cu₄Sc phase, with a small amount of Sc segregating at the grain boundaries to pin them. This grain boundary pinning helped to inhibit grain growth and further improve the strength. The main strengthening mechanisms identified in Cu-Cr-Sc alloys were dislocation strengthening and precipitation strengthening.