Dresden 2003 – wissenschaftliches Programm

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M: Metallphysik

M 32: Intermetallische Phasen II

M 32.4: Vortrag

Mittwoch, 26. März 2003, 17:15–17:30, IFW B

The influence of the chemical composition on the local lattice parameters of matrix and ordered precipitate phase in nickel-base superalloys investigated with convergent beam electron diffraction (CBED) — •Florian Pyczak¹, Horst Biermann², and Haël Mughrabi¹ — ¹Materials Science and Engineering, University Erlangen-Nürnberg, Erlangen, Germany — ²Institut für Werkstofftechnik, TU Bergakademie Freiberg, Freiberg, Germany

Nickel-base superalloys play an important role as high temperature materials. The soft nickel matrix is hardened with a high volume fraction of Ni₃(Al,Ti,…) precipitates, which can be as small as 300 nm. The aim of this study is to measure the effects of different alloying elements on the local lattice constant of each of the two phases. A transmission electron microscope (TEM) is used to determine the lattice constants with the necessary high lateral resolution by convergent beam electron diffraction (CBED), while the chemical composition can be determined with energy dispersive spectroscopy (EDS). These investigations were performed on nickel-base superalloys with different chemical composition in as received, heat treated and creep deformed state. The results should lead to a better understanding, how different alloying elements influence the lattice constants of matrix and precipitate phase and how these strain states change due to changes in the shape of the precipitate phase and the loss of coherency at the matrix-precipitate interface during high temperature annealing and deformation.