UNS C17500 (CW104C) Cobalt-Beryllium Copper
C17500 copper is a lightly alloyed grade of copper, formulated for primary forming into wrought products. CW104C is the EN numeric designation for this material. C17500 is the UNS number. Additionally, the EN chemical designation is CuCo2Be. And the British Standard (BS) designation is C112. Older literature may refer to this material as ASMT Alloy 10, but this is now discouraged.
It has the highest base cost among wrought coppers. In addition, it has a moderately high embodied energy and a moderately low thermal conductivity.
The properties of C17500 copper include four 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 C17500 copper to: wrought coppers (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
6.0 to 30 %
Fatigue Strength
170 to 310 MPa 25 to 45 x 103 psi
Poisson's Ratio
0.34
Rockwell B Hardness
38 to 99
Shear Modulus
45 GPa 6.5 x 106 psi
Shear Strength
200 to 520 MPa 29 to 75 x 103 psi
Tensile Strength: Ultimate (UTS)
310 to 860 MPa 45 to 120 x 103 psi
Tensile Strength: Yield (Proof)
170 to 760 MPa 25 to 110 x 103 psi
Thermal Properties
Latent Heat of Fusion
220 J/g
Maximum Temperature: Mechanical
220 °C 430 °F
Melting Completion (Liquidus)
1060 °C 1940 °F
Melting Onset (Solidus)
1020 °C 1870 °F
Specific Heat Capacity
390 J/kg-K 0.092 BTU/lb-°F
Thermal Conductivity
200 W/m-K 120 BTU/h-ft-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
24 to 53 % IACS
Electrical Conductivity: Equal Weight (Specific)
24 to 54 % IACS
Otherwise Unclassified Properties
Base Metal Price
60 % relative
Density
8.9 g/cm3 550 lb/ft3
Embodied Carbon
4.7 kg CO2/kg material
Embodied Energy
73 MJ/kg 31 x 103 BTU/lb
Embodied Water
320 L/kg 38 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
30 to 120 MJ/m3
Resilience: Unit (Modulus of Resilience)
120 to 2390 kJ/m3
Stiffness to Weight: Axial
7.5 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
9.7 to 27 points
Strength to Weight: Bending
11 to 23 points
Thermal Diffusivity
59 mm2/s
Thermal Shock Resistance
11 to 29 points
Alloy Composition
Among wrought copper alloys, the composition of C17500 copper is notable for including beryllium (Be) and cobalt (Co). Beryllium is used to permit precipitation hardening (which increases strength) without much effect on electrical conductivity, but at the cost of substantial toxicity. Cobalt is used to improve strength.
| Cu | 95.6 to 97.2 | |
| Co | 2.4 to 2.7 | |
| Be | 0.4 to 0.7 | |
| Si | 0 to 0.2 | |
| Al | 0 to 0.2 | |
| Fe | 0 to 0.1 | |
| res. | 0 to 0.5 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B441: Standard Specification for Copper-Cobalt-Beryllium, Copper-Nickel-Beryllium, and Copper-Nickel-Lead-Beryllium Rod and Bar (UNS Nos. C17500, C17510, and C17465)
Copper: Its Trade, Manufacture, Use, and Environmental Status, Gunter Joseph, 2001
Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993