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ASTM B685 Palladium-Copper Electrical Contact Alloy

ASTM B685 alloy is a precious metal alloy formulated for use in electrical contacts. It has a moderately low electrical conductivity and can have a moderately high tensile strength among precious metal electrical contact alloys.

The properties of ASTM B685 alloy include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare ASTM B685 alloy to: precious metal electrical contact alloys (top), all alloys in the same category (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

Poisson's Ratio


Shear Modulus

43 GPa 6.3 x 106 psi

Tensile Strength: Ultimate (UTS)

660 to 1060 MPa 95 to 150 x 103 psi

Thermal Properties

Latent Heat of Fusion

180 J/g

Melting Completion (Liquidus)

1230 °C 2240 °F

Melting Onset (Solidus)

1200 °C 2180 °F

Specific Heat Capacity

300 J/kg-K 0.071 BTU/lb-°F

Thermal Expansion

14 µm/m-K

Other Material Properties


11 g/cm3 670 lb/ft3

Electrical Conductivity: Equal Volume

5.0 % IACS

Electrical Conductivity: Equal Weight (Specific)

4.1 % IACS

Common Calculations

Stiffness to Weight: Axial

6.1 points

Stiffness to Weight: Bending

15 points

Strength to Weight: Axial

17 to 27 points

Strength to Weight: Bending

16 to 21 points

Thermal Shock Resistance

28 to 46 points

Alloy Composition

Palladium (Pd)Pd 59 to 60.5
Copper (Cu)Cu 39.5 to 40.5
Silver (Ag)Ag 0 to 0.1
Zinc (Zn)Zn 0 to 0.060
Iron (Fe)Fe 0 to 0.050
Cadmium (Cd)Cd 0 to 0.050
Lead (Pb)Pb 0 to 0.030
Aluminum (Al)Al 0 to 0.0050
Residualsres. 0 to 0.2

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

Followup Questions

Further Reading

ASTM B685: Standard Specification for Palladium-Copper Electrical Contact Material