ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Phase-field simulation of microstructure evolution in superalloys

Date: 09.11.2009
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 especi ally 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 signifi cant amounts of approximately ten alloying elements. In order to obtain the best high temperature properties these alloys are directionally solidi fied 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 solidi ed single crystal superalloys and the subsequent solution heat treatment. The modelling approach comprises phase- field simulations couples to calculation of phase equlibria and diff usion 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 solidi cation and solution heat treatment simulations are compared with experimental results.

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