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M: Metallphysik
M 32: Intermetallische Phasen II
M 32.4: Talk
Wednesday, March 26, 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.