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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session

MM 18.32: Poster

Montag, 31. März 2014, 18:00–20:00, P4

Microstructural analysis of the creep behavior of directionally solidified eutectic NiAl-Cr — •Antje Krüger, Michael Klimenkov, and Anton Möslang — Institute for Applied Materials - Applied Materials Physics, Karlsruhe Institute of Technology (KIT)

NiAl with its low creep resistance at T > 600 °C can be strengthened by the refractory element Chromium. The directionally solidified eutectic composite NiAl-34Cr (at%) forms long Cr-fibers with diameters between 200 nm and 700 nm depending on the production process. NiAl-Cr shows at high temperatures a better oxidation and creep resistance and a reduced brittle to ductile transition temperature (BDTT) than the binary system NiAl. Typical applications for this material would comprise devices in gasturbines and aeroplane turbines to get an improved energy efficiency.

In our study we present first results of creep tests measured at constant compressive loads and constant temperatures above 700 °C under vacuum conditions. The cylindrical specimens were manufactured by wire electro-discharge machining with a diameter of 3mm and a length of 6 mm. The microstructure of the tested specimens is analyzed by TEM. With this facility we can have a look on the microstructure to find out which mechanisms are responsible for the deformation and how the Cr-fibers strengthen the NiAl-matrix. Further investigations are done by EDX measurements and selected area diffraction patterns (SADP) to get information on the chemical composition and the crystal orientation of the NiAl matrix, the Cr fibers and the interface.

The authors thank the Helmholtz association for financial support.