|About this Abstract
||10th International Symposium on Superalloy 718 and Derivatives (2023)
||Superalloy 718 and Derivatives
||Tailoring the γ- γ′-γ″ Dual Superlattice Microstructure of Ni-based Superalloy IN725 by High Temperature Aging and Nb/Ta Additions for Superior Creep Properties
||Stoichko Antonov, Chang-Yu Hung, Jeffrey A. Hawk, Paul D. Jablonski, Martin Detrois
|On-Site Speaker (Planned)
Next generation energy systems require superior resistance to creep deformation due to the considerably pro-longed exposure times at operating stress and temperature. To improve the elevated temperature properties of Inconel alloy 725 (IN725), a corrosion resistant alloy, several variants with different Ti/Al ratio and judicious amounts of Nb and Ta were made. Furthermore, a high temperature aging (HTA) heat treatment – where a higher temperature first step was used to promote precipitate phase formation - was explored. These adjustments allowed tailoring of the amount and type of precipitate strengthening which led to significant increases in time to failure. The Ti/Al ratio was used to design alloys with preferential formation of γ′ or γ″ precipitates. Compact morphology precipitates, which have superior coarsening resistance, were formed in alloys with a low Ti/Al ratio. The HTA increased the creep life of various alloy formulations up to a maximum improvement of 371% as compared to the standard aging heat treatment. The Nb and Ta additions had a similar effect on increasing creep life by promoting and stabilizing γ″ precipitation. The positive effect of the additions was even more pronounced when coupled with the HTA. Although the low Ti/Al ratio resulted in favorable microstructures, the effect on the creep life was less evident than that of the HTA. The findings of this study enable design of dual superlattice alloys through microstructural engineering that yields superior performance alloys and can be applied to a wide range of alloys in the 718 and derivative family.
||Definite: At-meeting proceedings