Microscopic analysis of creep and damage of γ-γ′ two-phase nickel base superalloy

The microscopic evolution of creep and damage of a nickel base superalloy under elevated temperature tension was analyzed by assuming that the size and distribution of gamma' phase in alloy are random. The deformations and damages of gamma-matrix phase and gamma' precipitate phase under high temperature were calculated by using temperature dependent crystal viscoplastic damage constitutive relation. The calculated results show that the random distribution model of gamma' phase can describe non-uniformed microstructure deformation, stress distribution and local shearing band, and can predict the different possible damages in nickel base alloy. The results were compared with those calculated by simplifying period cell model without considering the randomness for the gamma' precipitates, which indicated the random distribution model is more reasonable than the simplifying period cell model.