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
0.37
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
Density
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
| Pd | 59 to 60.5 | |
| Cu | 39.5 to 40.5 | |
| Ag | 0 to 0.1 | |
| Zn | 0 to 0.060 | |
| Fe | 0 to 0.050 | |
| Cd | 0 to 0.050 | |
| Pb | 0 to 0.030 | |
| Al | 0 to 0.0050 | |
| res. | 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