Dresden 2017 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 22: Poster session I

MM 22.34: Poster

Monday, March 20, 2017, 19:00–20:00, P4

A detailed atomic investigation of the clustering and precipitation on a Friction-Stir-Welding simulated Al-Cu-Li(-Mg) alloy (AA2198) — •Danny Petschke, Frank Lotter, and Torsten Staab — Lehrstuhl für Chemische Technologie der Materialsynthese, Röntgenring 11, 97070 Würzburg

Al-Cu-Li-(Mg) alloys find wide applications in aviation and aerospace technology due to the reduction of weight and their high strength at the same time. After rolling sheets of these alloys, a defined heat treatment, following the solution annealing, leads to the formation of mainly T1-precipitates (Al2CuLi). These precipitates are highly efficient in blocking dislocation movements and, therefore, are responsible for the high strength of the alloy. When these sheets are joined by Friction-Stir-Welding (FSW), temperatures occurring in the Weld-Nugget (WN) are close to the material's solution treatment temperature (490-510°C). Hence, the T1-precipitates are completely dissolved in this region, which results in a significant hardness-drop of 25%. Obviously, only GP-zones/GPB-zones and CuMg-clusters of several Ångström in size are formed directly after welding by diffusion processes not understood in detail, yet. We followed the precipitation kinetics directly after Friction-Stir-Welding with DSC, SAXS and Positron-Annihilation-Spectroscopy (PAS). Therefore, a Welding-Simulator was developed to reproduce the temperature profile in the welded material.