Patent attributes
A copper alloy having an improved combination of yield strength and electrical conductivity consists essentially of, by weight, from 1% to 2.5% of nickel, from 0.5% to 2.0% of cobalt, from 0.5% to 1.5% of silicon, and the balance is copper and inevitable impurities. Further, the total nickel plus cobalt content is from 1.7% to 4.3%, the ratio of nickel to cobalt is from 1.01:1 to 2.6:1, the amount of (Ni+Co)/Si is between 3.5 and 6, the electrical conductivity is in excess of 40% IACS and the yield strength is in excess of 95 ksi. An optional inclusion is up 1% of silver. A process to manufacture the alloy includes the sequential steps of (a). casting; (b). hot working; (c). solutionizing; (d). first age annealing; (e). cold working; and (f). second age annealing wherein the second age annealing temperature is less than the first age annealing temperature.