Precipitate coarsening and its effects on the hot deformation behavior of the recently developed γ'-strengthened superalloys

Abstract Recently, the γ′-strengthened superalloys are of great interests in high temperature applications due to their excellent high temperature strength which is derived from the γ′ strengthening phase. For these γ′-strengthened superalloys, the changes in morphology, size and distribution of γ′ precipitates due to coarsening during thermal exposure have a significant impact on the properties of alloys. This article briefly summarizes the recent advances on the coarsening behavior of gamma prime precipitates in the recently-developed γ′-strengthened superalloys and its effects on the hot deformation behavior of superalloys, drawing specific examples on Allvac® 718PlusTM and Ni3Al-based intermetallic superalloys. It is found that the particle size plays an important role in morphological evolution of γ′ precipitates. For instance, the morphology of γ' precipitates evolves from cuboidal to strip-like or other complex structures in Ni3Al-based intermetallic alloys, while the γ' precipitates in Allvac® 718Plus alloy always present near-spherical morphology due to the relatively small initial particle size. The Lifshitz-Slyozof-Wagner (LSW) theory and its modifications, as well as Trans-Interface Diffusion Controlled (TIDC) theory have been applied to describing the coarsening kinetics of γ' precipitates. Additionally, the hot deformation behavior of γ′-strengthened superalloy is found to be greatly influenced by the coarsening of γ′ precipitates.