Characterisation of the precipitation in Al-Li-Cu-Mg-(Mn, Zr) alloys

Abstract

The three-dimensional atom probe has been used to characterize the precipitates in two Li-containing 2xxx series aluminium alloys: Al-6Li-Cu-Mg-0.2Mn (alloy A) and Al-6Li-Cu-Mg-0.03Zr (alloy B). The alloys have been heat treated at 150?C for times in the range 6-24 h. In alloy A, the particles identified can be classified into two categories: those rich in Cu and Mg (similar to GPB zones and S' precipitates); and spherical particles rich in Li (?' precipitates). Clusters rich in Li are also observed. The same phases are observable in alloy B, although growth of the ?' phase precipitates is accompanied by the formation of a Zr-rich phase similar to ?'