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A. Redermeier, E. Povoden-Karadeniz, E. Kozeschnik:
"First principles aided thermodynamic modeling of TCP phases in Ni-base superalloys";
Talk: X. seminar of Central European PhD students in Material Science, Kosice; 2016-04-04 - 2016-04-06.

The addition of refractory elements, like Mo, Re and W, to single-crystal Ni-base superalloys enhances solid solution strengthening. Unfortunately, these elements also promote the occurrence of topologically closed structures (TCP) phases, which decrease - due to their brittleness - the mechanical properties. Ru and Co, on the other hand, may decrease the formation of the TCP phases. Hence, it is desirable to get a deeper understanding of the thermodynamic impacts of different alloying elements and furthermore to provide quantitative results for the dependency between the volume fraction of TCP phases and the amount of alloying elements. Here, we calculate the binding enthalpies of different TCP phases by using first principles calculations. Combining the first principles results with the CALPHAD method enables us to predict the relative phase stabilities of different TCP phases. This work will provide a profounder understanding of the effect of alloying elements in Ni base superalloys.

TCP phases, Ni base superalloys, first principles, CALPHAD