Effect of trace copper on electrical and mechanical properties of pure silver wire

This study investigates the effect of trace copper (0.05 wt.%) doping on the electrical and mechanical properties of high-purity (99.99%) silver wire. Compared to pure Ag, the Ag-0.05Cu alloy exhibits minimal electrical degradation, with resistivity increasing only 0.63% (1.6005 vs. 1.5905 × 10 −8 Ω·m) in the annealed state. Crucially, trace Cu significantly enhances mechanical performance: in the work-hardened state, it achieves a 126% increase in tensile strength (399.9 vs. 317.6 MPa) and a 171% boost in microhardness (97.7 vs. 57.2 HV). Furthermore, Cu doping dramatically improves aging stability, retaining >98% hardness after 365 days at ambient temperature, versus ∼35% retention for pure Ag. This is attributed to Cu-induced grain refinement (22.4 vs. 55.2 μm), enhanced dislocation pinning, and suppressed recrystallization kinetics. The results demonstrate that ultralow Cu microalloying optimally balances silver’s high conductivity with superior strength and long-term stability for demanding electrical applications.