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UNS C96700 (Alloy 72C) Nickel-Beryllium Copper

C96700 copper is a copper-nickel alloy formulated for casting. Cited properties are appropriate for the heat treated (HT) condition. C96700 is the UNS number for this material. Older literature may refer to this material as ASTM Alloy 72C, but this is now discouraged.

It has the highest base cost among cast copper-nickels. In addition, it has the highest tensile strength and the highest embodied energy.

The graph bars on the material properties cards below compare C96700 copper to: cast 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

140 GPa 20 x 106 psi

Elongation at Break

10 %

Poisson's Ratio

0.33

Rockwell C Hardness

26

Shear Modulus

53 GPa 7.7 x 106 psi

Tensile Strength: Ultimate (UTS)

1210 MPa 180 x 103 psi

Tensile Strength: Yield (Proof)

550 MPa 80 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

310 °C 580 °F

Melting Completion (Liquidus)

1170 °C 2140 °F

Melting Onset (Solidus)

1110 °C 2040 °F

Specific Heat Capacity

400 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

30 W/m-K 18 BTU/h-ft-°F

Thermal Expansion

15 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

90 % relative

Density

8.8 g/cm3 550 lb/ft3

Embodied Carbon

9.5 kg CO2/kg material

Embodied Energy

140 MJ/kg 61 x 103 BTU/lb

Embodied Water

280 L/kg 34 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

99 MJ/m3

Resilience: Unit (Modulus of Resilience)

1080 kJ/m3

Stiffness to Weight: Axial

8.9 points

Stiffness to Weight: Bending

20 points

Strength to Weight: Axial

38 points

Strength to Weight: Bending

29 points

Thermal Diffusivity

8.5 mm2/s

Thermal Shock Resistance

40 points

Alloy Composition

Among cast copper alloys, the composition of C96700 copper is notable for including zirconium (Zr) and beryllium (Be). Zirconium is used to increase recrystallization temperature and to permit or facilitate certain forms of heat treatment. Beryllium is used to permit precipitation hardening (which increases strength) without much effect on electrical conductivity, but at the cost of substantial toxicity.

Copper (Cu) 62.4 to 68.8
Nickel (Ni) 29 to 33
Beryllium (Be) 1.1 to 1.2
Manganese (Mn) 0.4 to 1.0
Iron (Fe) 0.4 to 1.0
Titanium (Ti) 0.15 to 0.35
Zirconium (Zr) 0.15 to 0.35
Silicon (Si) 0 to 0.15
Lead (Pb) 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

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993