Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 16: Structural Materials

MM 16.1: Vortrag

Dienstag, 15. März 2011, 11:00–11:15, IFW D

Temperature dependent lattice misfit in Nickel-base superalloys - Simulation and experiment — •Steffen Neumeier and Mathias Göken — Lehrstühl für Allgemeine Werkstoffeigenschaften, Universität Erlangen-Nürnberg, Erlangen, Deutschland

Ni-base superalloys are widely used in high temperature applications like jet engines and land-based turbines, because of their excellent high temperature properties. They derive their excellent high temperature strength and creep resistance from the presence of a high volume fraction of Ni₃Al γ^′ precipitates (L1₂ structure), which are embedded coherently within the face centred cubic (A1) γ matrix. The magnitude and sign of the lattice misfit between γ and γ^′ are important parameters affecting the microstructural evolution and high temperature strength of Ni-base superalloys. Therefore the knowledge of the lattice misfit at application temperature is of great importance. In this study the lattice misfit of several 1^st, 2^nd and 4^th generation Ni-base superalloys in dependence of temperature has been measured by means of HRXRD and compared with lattice misfit simulations based on thermodynamic calculations. The influence of the thermal expansion coefficients and the change in the chemical composition of both γ and γ^′ due to the γ^′ dissolution with increasing temperature has been taking into account. The experimentally measured γ and γ^′ lattice parameters could be reproduced by the simulation and the γ/γ^′ lattice misfit could be reasonably predicted.