Influence of alloying elements and composition on microstructure and mechanical properties of Cu-Si, Cu-Ag, Cu-Ti, and Cu-Zr alloys

This study aims to quantitatively compare the effects of alloying elements on the microstructures and mechanical properties of Cu–Si, Cu–Ag, Cu–Ti, and Cu–Zr binary alloys over an alloying content range up to 2 wt%. The alloys were produced using vacuum arc melting, followed by homogenization and cold-rolling into plates. Subsequently, the annealing response of the cold-rolled plates was examined over a temperature range of 200–700 °C. The as-cast alloys show distinct microstructural features attributable to the alloying elements. Following the homogenization and cold-rolling processes, substantial microstructural transformations were observed. The analysis of mechanical properties revealed that solid solution hardening played a dominant role in increasing strength in Cu–Si alloys. Cu–Ag alloys displayed a minor increase in strength with alloying content, implying the influence of Cu–Ag precipitates on strength. Conversely, Cu–Ti and Cu–Zr alloys demonstrated remarkable strength improvements due to the presence of intermetallic precipitates and grain size reduction. While all other alloys displayed an inverse relationship between strength and elongation with increasing alloying content, the Cu-Si alloys exhibited a simultaneous enhancement of both strength and elongation. This effect can be attributed to the twinning-induced plasticity, brought about by the reduction of stacking fault energy in Cu through the addition of Si.