# UNS C64800 Cobalt-Silicon Bronze

C64800 bronze is a bronze formulated for primary forming into wrought products. Cited properties are appropriate for the H04 (full hard) temper. It has the highest electrical conductivity among wrought bronzes. In addition, it has the highest thermal conductivity and a moderately high base cost.

The graph bars on the material properties cards below compare C64800 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 10 ^{6} psi*

Elongation at Break

8.0 *%*

Poisson's Ratio

0.34

Shear Modulus

44 *GPa* 6.4 *x 10 ^{6} psi*

Shear Strength

380 *MPa* 55 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

640 *MPa* 94 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

630 *MPa* 91 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

220 *J/g*

Maximum Temperature: Mechanical

200 *°C* 390 *°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

260 *W/m-K* 150 *BTU/h-ft-°F*

Thermal Expansion

17 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

65 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

66 *% IACS*

## Otherwise Unclassified Properties

Base Metal Price

33 *% relative*

Density

8.9 *g/cm ^{3}* 550

*lb/ft*

^{3}Embodied Carbon

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

Embodied Energy

43 *MJ/kg* 18 *x 10 ^{3} BTU/lb*

Embodied Water

310 *L/kg* 37 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

51 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

1680 *kJ/m ^{3}*

Stiffness to Weight: Axial

7.4 *points*

Stiffness to Weight: Bending

18 *points*

Strength to Weight: Axial

20 *points*

Strength to Weight: Bending

19 *points*

Thermal Diffusivity

75 *mm ^{2}/s*

Thermal Shock Resistance

23 *points*

## Alloy Composition

Among wrought copper alloys, the composition of C64800 bronze is notable for including chromium (Cr) and cobalt (Co). Chromium additions permits certain types of heat treatment to improve mechanical strength. Cobalt is used to improve strength.

Cu | 92.4 to 98.8 | |

Co | 1.0 to 3.0 | |

Si | 0.2 to 1.0 | |

Fe | 0 to 1.0 | |

P | 0 to 0.5 | |

Ni | 0 to 0.5 | |

Sn | 0 to 0.5 | |

Zn | 0 to 0.5 | |

Cr | 0 to 0.090 | |

Pb | 0 to 0.050 | |

res. | 0 to 0.5 |

All values are % weight. Ranges represent what is permitted under applicable standards.