| 1 | Copper–Silver (CuAg) Silver-bearing copper wire | Approximately 0.05–0.25% silver; balance copper | Approximately 95–101% IACS, depending on silver level and processing | Higher creep resistance and strength retention than commercially pure copper; hard-drawn wire can provide substantially higher tensile strength than annealed wire | Maintains high conductivity while improving softening resistance and dimensional stability at elevated temperature | Higher material cost than pure copper; the conductivity benefit is smaller than the cost increase at low silver additions | High-speed motors, traction machines, generators, aerospace electrical systems, and high-temperature electromagnetic windings | Best high-conductivity upgrade |
| 2 | Copper–Chromium–Zirconium (CuCrZr) Precipitation-hardening copper alloy | Typically about 0.5–1.2% chromium and 0.03–0.30% zirconium; balance copper | Approximately 75–85% IACS after suitable heat treatment | Commonly about 450–700 MPa for strengthened wire, with strong resistance to softening at elevated temperature | Excellent combination of conductivity, mechanical strength, wear resistance, and thermal stability | Lower conductivity than CuAg or high-purity copper; heat treatment and processing control are important | High-current motor windings, resistance-welding equipment, generator components, demanding industrial coils, and compact electrical machines | Best strength–conductivity balance |
| 3 | Copper–Nickel–Silicon (CuNiSi) Age-hardenable copper alloy | Usually about 1–4% nickel and 0.5–2% silicon; exact composition varies by grade | Approximately 30–60% IACS, depending on composition and temper | Often about 600–900 MPa in precipitation-hardened conditions | High tensile strength, good fatigue resistance, and strong resistance to stress relaxation | Significantly lower conductivity than copper–silver alloys; requires controlled aging treatment for maximum performance | High-stress coils, compact motors, spring-like electrical contacts integrated into winding systems, and vibration-prone assemblies | Best for high mechanical loading |
| 4 | Low-Tin Copper (CuSn0.1–CuSn0.3) Lightly alloyed tin copper | Approximately 0.1–0.3% tin; balance copper | Approximately 80–95% IACS, depending on tin content and processing | Moderately higher strength and improved softening resistance than pure copper | Improved resistance to thermal softening and creep with relatively small conductivity loss | Not as strong as CuCrZr or CuNiSi; conductivity decreases as tin content rises | Automotive and industrial motor windings, elevated-temperature coils, and applications requiring a practical balance of cost and durability | Best practical upgrade for general windings |
| 5 | Higher-Tin Copper / Phosphor Bronze (CuSn4–CuSn8) Tin-rich copper alloy wire | Approximately 4–8% tin; some grades may include a small phosphorus addition | Typically about 13–45% IACS, depending on tin level and metallurgical condition | Often about 450–800 MPa, with good fatigue strength and spring characteristics | High strength, good fatigue resistance, and good resistance to corrosion and stress relaxation | Substantially lower conductivity and higher resistive heating than high-conductivity copper alloys | Specialized sensor coils, spring-loaded electromagnetic components, small actuators, control devices, and low-current windings | Specialist high-strength option |
| 6 | Copper–Tellurium (CuTe) Free-machining copper alloy | Approximately 0.4–0.7% tellurium; balance copper | Approximately 85–95% IACS | Moderate strength; valued more for manufacturability than for maximum tensile performance | Excellent machinability while retaining relatively high electrical conductivity | Not generally selected for the highest-strength or highest-temperature winding duty; tellurium content requires appropriate recycling and process controls | Machined electromagnetic components, formed terminals, specialized coils, and assemblies where machining efficiency is important | Best for manufacturability |