Wikipedia
Elgiloy
Elgiloy (Co-Cr-Ni Alloy) is a "super-alloy" consisting of 39-41% Cobalt, 19-21% Chromium, 14-16% Nickel, 11.3-20.5% Iron, 6-8% Molybdenum, and 1.5-2.5% Manganese.
It is used to make springs that are corrosion resistant and exhibit high strength, ductility, and good fatigue life. These same properties led to it being used for control cables in the Lockheed SR-71 Blackbird airplane.
Elgiloy specifications: AMS 5876, AMS 5833, UNS R30003