In Situ Synchrotron HEXRD Study on the Deformation Mechanism of a Nickel-Based Superalloy during Medium-Temperature Compression

Abstract

The γ′ phase has an important influence on the deformation mechanism of solid-solution strengthening nickel-based superalloys. The microfracture behavior of the alloy depends on the mechanism of stress and strain partitioning between the γ and γ′ phase under load. In this study, the in situ synchrotron radiation high-energy X-ray diffraction technique was used to observe the deformation process of the FGH96 nickel-based superalloy with a γ′ volume fraction of about 40% at 650 °C and 750 °C. The results show that the (111) reflection had the greatest stiffness and showed plastic deformation first; while the (200) reflection bore a larger load. The γ phase yielded first and began to deform plastically; then the load was transferred to the γ′ phase. At 650 °C, the plastic deformation of the γ′ phase was relatively higher; while at 750 °C, the γ′ particle basically maintained elastic deformation with a tiny amount of plastic deformation.