High-Temperature Pre-deformation and Rejuvenation Treatment on the Microstructure and Creep Properties of Ni-Based Single-Crystal Superalloys

In-Situ Monitoring of Phase Transition and Microstructure Evolution in Ni-Based Superalloys by Electrical Resistivity: Direct Comparison With Differential Scanning Calorimetry and Application to Case Studies

“…[69] After the heat treatment, and as expected from the experiment design, a high density of c/c¢ interfacial dislocation networks (white arrows), coarsened c¢ precipitates, and tertiary c¢ precipitates within c matrix (black arrows) are visible in the ECCI image of this sample (see Figure 14(c)). [65] These features are all in accordance with previous studies on pre-strain effect on Ni-based SX superalloys. [65,69] Microstructure observation revealed following changes after the heat treatment at 1100 °C: increase of dislocation density; increase of precipitate number density; pores that nucleated and grew during dislocation development.…”

“…[65] These features are all in accordance with previous studies on pre-strain effect on Ni-based SX superalloys. [65,69] Microstructure observation revealed following changes after the heat treatment at 1100 °C: increase of dislocation density; increase of precipitate number density; pores that nucleated and grew during dislocation development. From the fundamental results on Waspaloy, presented in a previous section, the distribution of finer c precipitates strongly affects the resistivity of the material.…”

“…[63,64] For this rejuvenation study, the temperature 950 °C was selected since deformation type at this temperature can trigger recrystallization at a relatively low strain magnitude. [29,65,66] After the tensile pre-straining shown in Figure 5(b), the same material was heated using the ETMT with the following rejuvenation treatment; 5 K/s to 1100 °C fi 1 K/s to 1225 °C fi 30 minutes dwell at 1225 °C fi 5 K/s to 1100 °C fi 6 hours dwell at 1100 °C fi 5 K/s to 100 °C. The rejuvenation temperature was chosen based on the DSC data (Figure 6(c)).…”

“…This concept is taken from pre-straining studies on Ni-based SX superalloys that showed elastic strain around slip bands that accelerates the development of a c/c¢ interfacial dislocation network and c¢ precipitate coarsening. [65,[67][68][69] Tensile deformation was performed on CMSX-4Ò at room-temperature (RT) using the ETMT system and interrupted at 7 pct plastic strain. The same CMSX-4Ò sample was then heat-treated at 1100 °C for 6 hours by DC current in the ETMT to develop a dislocation network and coarsen precipitates.…”