Effect of microalloying with different contents of Al and Sc on the microstructure and properties of pure copper

Copper, as a key conductor material for high-power devices, is severely restricted in high-temperature environments and high-end applications due to its low strength and insufficient high-temperature stability. In this study, Cu-Al-Sc alloys with different contents were prepared based on the regulation strategy of an Al/Sc atomic ratio of 3, and the effects of microalloying with different Al and Sc contents on the microstructure and properties of pure copper were systematically investigated using OM, EBSD, and TEM. The results show that the Cu-0.021Al-0.012Sc alloy has the best comprehensive performance. In the cold-rolled state, its electrical conductivity, hardness, and tensile strength are 94.4% IACS, 139.8 HV, and 403 MPa, respectively. After high-temperature treatment at 850 °C for 30 min, the electrical conductivity and hardness are 97.6% IACS and 86.4 HV, respectively. The grain size is refined from 237.49 μm to 77.88 μm, and the softening temperature is increased from 165 °C to 515 °C. The significant increase in softening temperature is mainly attributed to a dual mechanism: Firstly, the solid solution of Al and Sc causes lattice distortion and hinders dislocation slip, while Sc segregation at grain boundaries reduces grain boundary energy and inhibits recrystallization nucleation and growth. Secondly, the precipitation of oxide phases pins grain boundaries and dislocations, inhibiting the transformation of deformation texture (Brass/S) to recrystallization texture (Cube/Goss), and the inhibitory effect increases with the increase of Sc content, thereby significantly improving the anti-softening performance of pure copper.