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MM: Fachverband Metall- und Materialphysik
MM 38: Structural materials
MM 38.4: Talk
Wednesday, April 2, 2014, 11:00–11:15, IFW B
Delta' precipitation in Al-Cu-Li alloys — •Pascal Neibecker1, Haider Ferdinand1, and Al-Kassab Tala'at2 — 1University of Augsburg, Augsburg, Germany — 2King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
Due to their high strength, high Young's modulus and low density, Al-Cu-Li alloys are of special interest in aerospace applications. The process mainly responsible for the excellent mechanical properties of these alloys is precipitation hardening. Understanding the microstructure evolution upon artificial aging of Al-Cu-Li alloys and the corresponding underlying mechanisms is thus of great importance. In mechanically untreated binary Al-Li and ternary Al-Cu-Li alloys with a high Li content, the major hardening phase is the metastable delta' (Al3Li) phase which already partly develops during natural aging of the alloy. The formation mechanism leading to delta' precipitation thereby was controversially discussed in the last decades.
This work investigates the kinetics of the delta' evolution in an Al-1.7 at. % Cu- 5.6 at. % Li model alloy upon artificial aging at 160 °C with Differential Scanning Calorimetry and Atom Probe Tomography. Here, the volume fraction and size evolution of the delta' phase is determined and additionally, by using the Pearson coefficient, quantitative statements about Li and Cu ordering in the alloy are made. The findings give insights into the formation mechanism of the delta' phase in Al-Cu-Li alloys.