Place: Department of Metallurgy and Materials, University of Birmingham, Birmingham, UK
Nils Warnken, Department of Metallurgy and Materials, University of Birmingham, Birmingham, United Kingdom
Superalloys are a class of metallic alloy developed over the last decades especially for high temperature applications. Ni-based single crystal superalloys form a subgroub which are
used for turbine blades and vanes in the hottest section of gas turbines. Based on nickel,
these alloys contain significant amounts of approximately ten alloying elements. In order
to obtain the best high temperature properties these alloys are directionally solidified and
subsequently heat treated. Heat treatment cycles of modern single crystal superalloys
take up to three days at temperatures around 1330 °C.
The work presented here aims at deriving a modelling approach for the microstructure evolution in directionally solidied single crystal superalloys and the subsequent solution heat treatment. The modelling approach comprises phase-field simulations couples to calculation of phase equlibria and diffusion data via the CALPHAD method.
Microstructure simulations for the whole geometry of a turbine blade are still not possible, even on todays supercomputers. Therefore an isothermal section approach is introduced to bridge the length scales between the thermal field and the microstructure. The results of the solidication and solution heat treatment simulations are compared with experimental results.