Impact of Aging Temperature on the Performance of a Nickel-Iron-Based Superalloy

In this study, the effects of aging temperature on the microstructure and properties of a nickel-iron (Ni-Fe)-based superalloy were investigated. On the one hand, owing to the increase in the size and particle spacing of Ni3Al (γ′) precipitate, long-term aging induced a significant drop in the alloy strength. Moreover, the increasing aging temperature from 700 °C to 750 °C further induced more than 75 MPa decline in the alloy yield strength. Furthermore, it led to a decrease in the critical stress because of dynamic recrystallization. On the other hand, the long-term aging increased the alloy’s ductility. The crack propagation along the grain boundary was inhibited, because of the decreasing grain boundary brittleness. Although the grain boundary precipitates changed from carbide to γ′ when the aging temperature increased, a distinct change in the alloy’s ductility was not observed. The transmission electron microscopy results showed that both precipitates were sheared by the grain boundary during the alloy deformation. These results confirm that aging temperature has less effect on alloy’s ductility.