US Patent 7338631 Copper alloy and method of manufacturing the same

This copper alloy contains at least zirconium in an amount of not less than 0.005% by weight and not greater than 0.5% by weight, includes a first grain group including grains having a grain size of not greater than 1.5 μm, a second grain group including grains having a grain size of greater than 1.5 μm and less than 7 μm, the grains having a form which is elongated in one direction, and a third grain group including grains having a grain size of not less than 7 μm, and also the sum of α and β is greater than γ, and α is less than β, where α is a total area ratio of the first grain group, β is a total area ratio of the second grain group, and γ is a total area ratio of the third grain group, based on a unit area, and α+β+γ=1.