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Abstract

Superalloys are of technological importance since they exhibit superior properties at elevated temperatures. Ni-base superalloys possess the unusual microstructure composed of thin γ-phase channels combined with dominant γ′-phase precipitates. In this study, dislocation induced strains at the interface are used to describe coherent and semi-coherent interfaces. We find, that there is a driving force which prevents precipitate coalescence. Moreover, the presented study shows that in contrast to coherent interfaces, semi-coherent interfaces significantly reduce repulsive stresses in the gamma-channels and promote precipitate coalescence. This knowledge is then used in a phase field simulation to investigate the microstructure evolution during long term aging of γ/γ′-forming cobalt base superalloys is analyzed.