γ′-phase morphology of Ni-based single crystal superalloys as an indicator of the stress concentration in the vicinity of pores

The morphological evolution of the γ′-phase in the vicinity of pores in a second generation Ni-based single crystal superalloy has been studied during the very first hours of high temperature/low stress creep. Over a critical pore size, kinetics of γ′-phase directional coarsening depends on the stress concentration around the pore. It is shown, using finite element modeling, that both differences in kinetics and orientation dependence of γ′-precipitates rafting derive from the local principal elastic stress field.Under such conditions, γ′-phase morphological evolution can be considered as an indicator of the local stress field.