CuNi2Si – UNS.C64700  Nickel Silicon Copper, which is an age-hardening alloy, higher alloyed in comparison with CuNi1.5Si, for current-carrying formed parts. It has an a-structure with very fine precipitations and recommends itself both for lead frames which require a high rigidity of the pins and for connector with high demands on the electrical conductivity, strength and relaxation behavior. In addition, the CuNi2Si can also be used for current-carrying formed parts and contact springs due to its good fatigue strength, forming and spring properties.

Chemical Composition:

Ni: 1.60-2.20%
Si: 0.40-0.80%
Fe: 0.10% Max.
Zn: 0.50% Max.
Cu: Balance
Note: Copper plus additions equal 99.50% minimum.

Typical Physical Properties:

Specific Gravity: 8.80-8.90 g/cm3
Coefficient of Thermal Expansion per °C: 17 x 10-6 /K (20-300°C)
Electrical Conductivity (% IACS): 38 (22 Ms/m)
Thermal Conductivity (W/mk): 250 
Modulus of Elasticity (10 3 MPA): 130

Note: 
1). the units are based upon US Customary.
2). the typical physical properties apply to age hardened products.

International Specification:

Rods/Bars/Plates/Sheets: UNS.C64700,  RWMA Class 3

European Standards: CuNi2Si, DIN 2.0855, CW111C to EN