Dresden 2009 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 31: Topical Session High Temperature Materials II

MM 31.5: Talk

Wednesday, March 25, 2009, 16:15–16:30, IFW A

Modelling of topologically close packed phases in Ni-based superalloys based on thermodynamic and kinetic CALPHAD calculations — •Ralf Rettig and Robert F. Singer — Institute of Science and Technology of Metals, Department of Materials Science and Engineering, University of Erlangen, Martensstr. 5, D-91058 Erlangen, Germany

Single crystal Nickel-based superalloys are important high temperature load bearing materials used in particular for turbine blades in industrial gas turbines and aero engines. These materials show unique high-temperature properties up to high homologous temperatures. Nevertheless modern superalloys are often susceptible to brittle topologically close packed (TCP) phase formation. The aim of the current development of gas turbines is to reduce carbon dioxide emission and fuel consumption and therefore to increase efficiency. To achieve that, the firing temperature has to be increased and materials have to be found that are capable of enduring higher temperatures. Prospective candidates are single crystal superalloys with additions of rhenium and ruthenium. In this study computer modelling based on thermodynamic and kinetic CALPHAD calculations is used to systematically explore the mechanisms of phase stability regarding TCP phase formation in complex single crystal superalloys containing rhenium and ruthenium. Methods are developed for quantitative prediction of TCP phase fractions in dependence of time, temperature and alloy composition and an evaluation with experimental results is presented.