Influence of Homogenization Duration on Interdendritic Phase Elimination and Hardness Behavior in AD۷۳۰ Nickel-based Superalloy

In this study, the effect of homogenization time on the microstructural evolution and mechanical properties of the cast AD۷۳۰ superalloy at ۱۱۰۰ °C was investigated. The as-cast microstructure consisted of a dendritic structure along with interdendritic phases, including η phase, Laves phase, γ/γ′ eutectic, and MC carbides. Microscopic examinations and localized analyses revealed that the eutectic and Laves phases were completely dissolved during the early stages of homogenization, while the η phase disappeared after ۱۰ hours of treatment. Prolonging the homogenization time promoted chemical uniformity and gradual elimination of the dendritic structure, resulting in a nearly uniform microstructure after ۲۵ hours. However, at this stage, the formation of voids was detected, indicating adverse effects due to over-homogenization. Hardness measurements showed a continuous decrease in hardness with increasing homogenization time, attributed to the gradual dissolution of the strengthening γ′ precipitates. Based on these results, an optimal homogenization duration of ۱۵ to ۲۰ hours at ۱۱۰۰ °C is suggested, which can eliminate undesirable phases and enhance compositional uniformity while avoiding structural defects.

کلیدواژه ها:

AD۷۳۰ superalloy ، Homogenization treatment ، Microstructural refinement ، Interdendritic phase elimination ، Hardness reduction