What is an alloy of copper and nickel used in electrical resistance wire?

Alloy wires of copper and nickel come in many varieties and are sometimes called cupro-nickels.

They can be found containing:
  • Copper with 10% nickel
  • Copper with 30% nickel
  • Copper with 25% nickel with 0.05-0.4% manganese
  • Copper with 45% nickel (also known as constantan)

Alloy wire containing both copper and nickel retain their strength at elevated temperatures compared to copper alloys without nickel. Also, they are beneficial in outstanding resistance to corrosion, particularly from sea water.