What is "cunife"

Cunife is an alloy of copper (Cu), nickel (Ni), iron (Fe), and in some cases cobalt (Co). The alloy has the same linear coefficient of expansion as certain types of glass, and thus makes an ideal material for the lead out wires in light bulbs and thermionic valves. It is a magnetic alloy and can be used for making magnets.

Fernico exhibits a similar property.

• Cunife 1 consists of 60% Cu, 20% Ni, and 20% Fe.
• Cunife 2 consists of 60% Cu, 20% Ni, 17.5% Fe, and 2.5% Co.

At one point Fender Musical Instruments Corporation used Cunife magnets in their Wide-Range humbucking pickups, however discontinued use, due to Cunife being hard to source.