Nickel-based superalloy, relation between non-linear ultrasound and microstructure changes due to creep damages

Nickel-based superalloy, Inconel 718, has high temperature strength effected by γ”(Ni 3 Nb) phase at approximately 973 K. Inconel 718 is characterized in that the γ”-phase disappearance leading to the creep destruction. In the study, we applied the nonlinear ultrasonic for evaluation the creep damage and the microstructural degradation in γ”for Inconel 718 plates. The nonlinear ultrasonic holds the potential of becoming the primary means of characterizing creep in metals, because it can probe the change of dislocation structure during the creep. Its sensitivity to microstructural evolutions during the creep is often higher than that of linear properties. We elucidated the relationship between microstructural change and the evolutions of nonlinear acoustic characterizations three-wave- interacting, with electromagnetic acoustic resonance (EMAR) throughout the creep lifetime, nonlinearly was relationship change in dislocation density. X‐ray diffraction and EBSD, SEM images supported this view.