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.
| Cu | 62.4 to 68.8 | |
| Ni | 29 to 33 | |
| Be | 1.1 to 1.2 | |
| Mn | 0.4 to 1.0 | |
| Fe | 0.4 to 1.0 | |
| Ti | 0.15 to 0.35 | |
| Zr | 0.15 to 0.35 | |
| Si | 0 to 0.15 | |
| Pb | 0 to 0.010 | |
| res. | 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