Beryllium-free high-strength copper alloys
A beryllium-free high-strength copper alloy includes, about 10-30 vol % of L1 2 -(Ni,Cu) 3 (Al,Sn), and substantially excludes cellular discontinuous precipitation around grain boundaries. The alloy may include at least one component selected from the group consisting of: Ag, Cr, Mn, Nb, Ti, and V, and the balance Cu.
1. A method for manufacture of an essentially beryllium (Be) free copper based alloy comprising by volume 10%-30% of a multicomponent, intermetallic phase based on a L1 2 -(Ni,Cu) 3 (Al,Sn) microstructure comprising the steps of:
(a) forming an ingot consisting essentially of by weight percent 19-24% nickel (Ni), 3-6.5% tin (Sn), 1.2-2.0% aluminum (Al), optionally up to 1% by weight of at least one element (X) selected from the group consisting of silver (Ag), chromium (Cr), manganese (Mn), niobium (Nb), titanium (Ti) and vanadium (V), no more than 0.06% beryllium (Be), no more than 0.05% boron (B) and the balance copper (Cu), and
(b) heat treating the alloy by an aging heat treatment including at least a first step and a second step, wherein the first step includes heating the alloy to a temperature between 600° C. and the solvus temperature of the L1 2 phase kept below and less than 800° C. and the second step includes heating the alloy to a temperature between 450 and 550° C.
2. The method of claim 1 further including at least one homogenization step at about 850° to 900° C. before the aging steps.