Patent ID: 6893514

Claim:
A high-mechanical strength copper alloy, consisting essentially of 3.5 to 4.5% by mass of Ni, 0.7 to 1.0% by mass of Si, 0.01 to 0.20% by mass of Mg, 0.05 to 1.5% by mass of Sn, 0.2 to 1.5% by mass of Zn, and less than 0.005%bymass (including0%bymass) of S, with the balance being made of Cu and inevitable impurities, wherein a diameter of a crystal grain in tne alloy is from more than 0.00 1 mm to 0.025 mm; and the ratio (a/b), between a longer diameter a of a crystal grain on a cross section parallel to a direction of final plastic working, and a longer diameter b of a crystal grain on a cross section perpendicular to the direction of final plastic working, is 1.5 or less, wherein the alloy has a tejisile strength of 800 N/mm 2 or more, and wherein the alloy has a stress relaxation ratio of 10% or less.