Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.60: Poster

Montag, 11. März 2013, 18:00–20:00, Poster E

Phase field modeling of interdiffusion microstructures in Ni-base superalloys — •Leslie Mushongera, Micheal Fleck, and Heike Emmerich — University of Bayreuth

The effect of the refractory element rhenium(Re) on the kinetics of coarsening in negatively misfitting ni-based superalloys during heat treatment is studied. A multicomponent phasefield model coupled with inputs from thermodynamic and kinetic databases to provide the relevant driving forces is developed. In order to realistically capture the complex nature of interdiffusion, the CMSX4 and CMSX6 superalloys with well-defined weight percent contents are analyzed.

Microstructural evolution is first studied in the presence of a lattice misfit with inhomogeneous elastic constants. Cuboidal precipitates arranged in a square array are formed. We then study the system under external load along a cubic axis. It is observed that the precipitates become anisotropic and the orientation differs depending on the sign of the applied stress. Simultaneously, we determine the mechanism by which Re reduces coarsening. It is seen that Re additions substantially reduce the rate of precipitate coarsening by keeping their shape almost cuboidal, which is the interfacial energy minimizing configuration. Re also reduces coarsening by hindering the growth of the rafts. In addition,we derive stereological measures to characterize the kinetics of coarsening.