UNS C64700 Nickel-Silicon Bronze
C64700 bronze is a bronze formulated for primary forming into wrought products. Cited properties are appropriate for the TF00 (precipitation hardened) temper. C64700 is the UNS number for this material. Additionally, the EN chemical designation is CuNi2Si.
It has a fairly high thermal conductivity among wrought bronzes. In addition, it has a moderately high electrical conductivity and a moderately low ductility.
The graph bars on the material properties cards below compare C64700 bronze to: wrought bronzes (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
9.0 %
Poisson's Ratio
0.34
Shear Modulus
44 GPa 6.3 x 106 psi
Shear Strength
390 MPa 57 x 103 psi
Tensile Strength: Ultimate (UTS)
660 MPa 96 x 103 psi
Tensile Strength: Yield (Proof)
560 MPa 82 x 103 psi
Thermal Properties
Latent Heat of Fusion
220 J/g
Maximum Temperature: Mechanical
200 °C 400 °F
Melting Completion (Liquidus)
1090 °C 1990 °F
Melting Onset (Solidus)
1030 °C 1890 °F
Specific Heat Capacity
390 J/kg-K 0.093 BTU/lb-°F
Thermal Conductivity
210 W/m-K 120 BTU/h-ft-°F
Thermal Expansion
17 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
38 % IACS
Electrical Conductivity: Equal Weight (Specific)
38 % IACS
Otherwise Unclassified Properties
Base Metal Price
31 % relative
Density
8.9 g/cm3 550 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)
57 MJ/m3
Resilience: Unit (Modulus of Resilience)
1370 kJ/m3
Stiffness to Weight: Axial
7.3 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
21 points
Strength to Weight: Bending
19 points
Thermal Diffusivity
59 mm2/s
Thermal Shock Resistance
24 points
Alloy Composition
Among wrought copper alloys, the composition of C64700 bronze is notable for including silicon (Si) and nickel (Ni). Silicon is used to increase strength at the expense of ductility. It also lowers the melting temperature and raises the fluidity of the alloy. Nickel is used to improve strength (particularly at elevated temperatures) and corrosion resistance.
| Cu | 95.8 to 98 | |
| Ni | 1.6 to 2.2 | |
| Si | 0.4 to 0.8 | |
| Zn | 0 to 0.5 | |
| Fe | 0 to 0.1 | |
| Pb | 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 B411: Standard Specification for Copper-Nickel-Silicon Alloy Rod and Bar
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