The suppression of topologically close-packed phases (TCP) in nickel-based single-crystal superalloys by the addition of ruthenium is modeled with a fully multicomponent mesoscale precipitation model based on the numerical Kampmann-Wagnermethod using thermodynamic CALPHAD-calculations. For the application of the model in ruthenium-containing superalloys, mobility assessments of the binary systems nickel-ruthenium (NiRu) and nickel-rhenium (Ni-Re) were performed to create a new mobility database. It is postulated that the dominating effect of ruthenium regarding more sluggish TCP-phase precipitation is a change of interface energy reducing the number of precipitates nucleating. The precipitation sequences occurring during TCPphase precipitation can be explained using CALPHAD thermodynamics.

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