Precipitation Sequences in Two Al-Li-Cu Alloys
The precipitation sequences in two Al-Li-Cu alloys with similar Cu concentration and different Li concentration have been studied by small-angle X-ray scattering using synchrotron light, in combination with transmission electron microscopy. The sequence ranges from phases formed during natural ageing to the hardening ones obtained by artificial ageing at 155°C. It is found that the low Li-containing alloy shows first Cu-rich clusters at room temperature followed by T1 precipitates, while the high Li-containing alloy shows first δ’-Al3Li precipitates and then formation of T1 phase in coexistence with the δ’. The influence of alloy composition on T1 nucleation and growth kinetics is discussed in light of the experimental results.
Yves Bréchet, Emmanuel Clouet, Alexis Deschamps, Alphonse Finel and Frédéric Soisson
B. Decreus et al., "Precipitation Sequences in Two Al-Li-Cu Alloys", Solid State Phenomena, Vols. 172-174, pp. 267-272, 2011