# 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 10 ^{6} psi*

Elongation at Break

10 *%*

Poisson's Ratio

0.33

Rockwell C Hardness

26

Shear Modulus

53 *GPa* 7.7 *x 10 ^{6} psi*

Tensile Strength: Ultimate (UTS)

1210 *MPa* 180 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

550 *MPa* 80 *x 10 ^{3} 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/cm ^{3}* 550

*lb/ft*

^{3}Embodied Carbon

9.5 *kg CO _{2}/kg material*

Embodied Energy

140 *MJ/kg* 61 *x 10 ^{3} BTU/lb*

Embodied Water

280 *L/kg* 34 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

99 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

1080 *kJ/m ^{3}*

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 *mm ^{2}/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