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UNS C70260 (CW111C) Nickel-Silicon Copper

C70260 copper is a copper-nickel alloy formulated for primary forming into wrought products. CW111C is the EN numeric designation for this material. C70260 is the UNS number.

It can have a moderately high electrical conductivity among wrought copper-nickels. In addition, it has the lowest embodied energy and a moderately high thermal conductivity.

The properties of C70260 copper include five common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C70260 copper to: wrought copper-nickels (top), all copper alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

120 GPa 17 x 106 psi

Elongation at Break

9.5 to 19 %

Poisson's Ratio


Shear Modulus

44 GPa 6.3 x 106 psi

Shear Strength

320 to 450 MPa 47 to 65 x 103 psi

Tensile Strength: Ultimate (UTS)

520 to 760 MPa 75 to 110 x 103 psi

Tensile Strength: Yield (Proof)

410 to 650 MPa 59 to 94 x 103 psi

Thermal Properties

Latent Heat of Fusion

220 J/g

Maximum Temperature: Mechanical

200 °C 400 °F

Melting Completion (Liquidus)

1060 °C 1940 °F

Melting Onset (Solidus)

1040 °C 1910 °F

Specific Heat Capacity

390 J/kg-K 0.093 BTU/lb-°F

Thermal Conductivity

160 W/m-K 90 BTU/h-ft-°F

Thermal Expansion

17 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

40 to 50 % IACS

Electrical Conductivity: Equal Weight (Specific)

40 to 51 % IACS

Otherwise Unclassified Properties

Base Metal Price

31 % relative


8.9 g/cm3 560 lb/ft3

Embodied Carbon

2.7 kg CO2/kg material

Embodied Energy

43 MJ/kg 19 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

46 to 140 MJ/m3

Resilience: Unit (Modulus of Resilience)

710 to 1810 kJ/m3

Stiffness to Weight: Axial

7.3 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

16 to 24 points

Strength to Weight: Bending

16 to 21 points

Thermal Diffusivity

45 mm2/s

Thermal Shock Resistance

18 to 27 points

Alloy Composition

Among wrought copper alloys, the composition of C70260 copper is notable for including silicon (Si) and phosphorus (P). Silicon is used to increase strength at the expense of ductility. It also lowers the melting temperature and raises the fluidity of the alloy. Phosphorus is used as an alloy deoxidizer, and to reduce vulnerability to dezincification.

Copper (Cu) 95.8 to 98.8
Nickel (Ni) 1.0 to 3.0
Silicon (Si) 0.2 to 0.7
Phosphorus (P) 0 to 0.010
Residuals 0 to 0.5

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM B422: Standard Specification for Copper-Aluminum-Silicon-Cobalt Alloy, Copper-Nickel-Silicon-Magnesium Alloy, Copper-Nickel-Silicon Alloy, Copper-Nickel-Aluminum-Magnesium Alloy, and Copper- Nickel-Tin Alloy Sheet and Strip

ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015