Copper-Based Alloys with Optimized Hardness and High Conductivity: Research on Precipitation Hardening of Low-Alloyed Binary CuSc Alloys

Abstract

Copper alloys, combining optimized strength with high electrical and thermal conductivity, are analyzed in-depth, in order to meet the increasing requirements of today’s and tomorrow’s applications in the electrical and automotive industries. The conducted research analyzes alloys with up to 0.3 wt.% scandium, as an alloying element with limited solubility in copper. For the simultaneous enhancement of mechanical strength and conductivity, precipitation hardening is the conducted process method, accompanied by experimental and simulation-based investigations. Therefore, the influence of aging temperatures, in the range of 350 °C to 500 °C, is analyzed in combination with 25%, 50%, and 75% prior cold deformation. CuSc starts precipitating at 375 °C, without prior cold working, whereas mechanical deformation refines the growing intermetallic precipitates. Higher temperatures improve the formation of precipitates but carry the risk of overaging. The first key achievement is to use a thoroughly examined thermomechanical treatment, investigating the growth of precipitates to reach significantly higher hardness than the benchmark alloy, CuZr0.15. Furthermore, the analyzed CuSc alloys show advantages in the investigated recrystallization behavior, making them, especially, applicable for higher operating temperatures. Future research will assess ternary alloying combinations, to further scoop the latent potential of CuSc alloys.