CuNi2Si
CW111CNickel-silicon precipitation-hardened copper — high conductivity (35-45% IACS) + high strength (UTS 600-750 MPa aged). THE lead-free alternative to CuBe2 for connectors where Be toxicity is a concern. Used for high-reliability connectors, relay springs, IC sockets, and automotive electrical contacts. Trade names: C70250 (Wieland), Corson alloy.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | UNS | USA | UNS C70250 | C70250 | REF |
| 🇪🇺 | EN | Europe | CuNi2Si / CW111C | CW111C | 100% |
Sources: ASTM B422, EN 12163
Chemical composition comparison (wt%)
Side-by-side: CuNi2Si (EN) (EN 12163) vs CuNi2Si / CW111C (EN) (EN 12163)
| Element | CuNi2Si (EN) | CuNi2Si / CW111C (EN) | Overlap |
|---|---|---|---|
| Si | 0.4–0.8% | 0.4–0.8% | OK |
| Ni | 1.6–2.5% | 1.6–2.5% | OK |
| Cu | — | — | — |
Mechanical properties
Aged
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 600–750 | MPa |
| Yield Strength | 500–650 | MPa |
| Elongation | 5–12 | % |
| Elastic Modulus | ≥ 131 | GPa |
| Density | ≥ 8.81 | g/cm3 |
Compatibility verdict
CuNi2Si and CuNi2Si / CW111C: 100% composition match
Close equivalents but NOT identical.
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