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ASTM B628 Silver-Copper Eutectic Electrical Contact Alloy

ASTM B628 Ag-Cu is a precious metal alloy formulated for use in electrical contacts. It has a moderately high electrical conductivity among the precious metal electrical contact alloys in the database.

The properties of ASTM B628 Ag-Cu include nine common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare ASTM B628 Ag-Cu 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

83 GPa 12 x 106 psi

Elongation at Break

1.1 to 17 %

Poisson's Ratio


Shear Modulus

31 GPa 4.4 x 106 psi

Shear Strength

210 to 430 MPa 31 to 63 x 103 psi

Tensile Strength: Ultimate (UTS)

350 to 760 MPa 50 to 110 x 103 psi

Thermal Properties

Latent Heat of Fusion

140 J/g

Melting Completion (Liquidus)

780 °C 1430 °F

Melting Onset (Solidus)

780 °C 1430 °F

Specific Heat Capacity

280 J/kg-K 0.066 BTU/lb-°F

Thermal Expansion

19 µm/m-K

Other Material Properties


10 g/cm3 630 lb/ft3

Electrical Conductivity: Equal Volume

84 % IACS

Electrical Conductivity: Equal Weight (Specific)

75 % IACS

Common Calculations

Stiffness to Weight: Axial

4.6 points

Stiffness to Weight: Bending

14 points

Strength to Weight: Axial

9.5 to 21 points

Strength to Weight: Bending

11 to 18 points

Thermal Shock Resistance

16 to 34 points

Alloy Composition

Silver (Ag)Ag 71 to 73
Copper (Cu)Cu 26.6 to 29
Zinc (Zn)Zn 0 to 0.060
Iron (Fe)Fe 0 to 0.050
Cadmium (Cd)Cd 0 to 0.050
Phosphorus (P)P 0 to 0.030
Lead (Pb)Pb 0 to 0.030
Nickel (Ni)Ni 0 to 0.010
Aluminum (Al)Al 0 to 0.0050
Residualsres. 0 to 0.21

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

Followup Questions

Similar Alloys

Further Reading

ASTM B628: Standard Specification for Silver-Copper Eutectic Electrical Contact Alloy

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015