Characterization of the precipitation in Al–Li–Cu–Mg–(Mn, Zr) alloys

Abstract

The 3D atom probe has been used to characterise the precipitates in two Licontaining 2xxx series aluminium alloys: Al-6Li-Cu-Mg-0.2Mn (Alloy A) and Al6Li-Cu-Mg-0.03Zr (Alloy B). The alloys have been heat-treated at 150°C for a range of times varying from 6h to 24h. 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 δ', spherical particles rich in Li. Clusters rich in Li, are observed in addition to these particles. The same phases are observable in the Alloy B, though the growth of the δ' phase precipitates is accompanied by the formation of a Zr-rich phase similar to β'.

Analytical modelling of the influence of local mixed mode displacements on roughness induced crack closure

“…Extensive study of these alloys microstructure was performed using TEM and DSC and is presented in refs. [15,16,17,18]. For the present study, all alloys were artificially aged at 190ºC for 12 hours.…”

Formation mechanisms of precipitates in an Al–Cu–Li–Zr alloy and their effects on strength and electrical resistance of the alloy

“…The main endothermic peaks appeared around 650 • C in DSC curves. In other research, this temperature was attributed to the melting point of AA2090 alloy [16,17]. One also can observe in this figure that by increasing the heating rate, peak of precipitation (T f p ) shifted from 255 • C to 275 • C while the peak of dissolution (T d p ) shifted from 482 • C to 520 • C. Effects of heating rate on precipitation of T 1 phase is presented in Fig.…”

Relations between microstructure, precipitation, age-formability and damage tolerance of Al–Cu–Mg–Li (Mn, Zr, Sc) alloys for age forming

“…The size of the clusters is similar for the three ageing conditions. The average composition of the clusters does not vary greatly with time [15]. In addition to the clusters, Cu/Mg-rich precipitates were observed.…”

“…Three dimensional atom probe (3DAP) analysis on alloys 3, 4 and 6 was performed by Davin and coworkers [15,16] using an energy-compensated optical position sensitive atom probe. For all alloys studied by 3DAP Cu-Mg co-clusters were identified after ageing at 150ºC.…”