With these alloys the TTT diagram will not show phase transformations as such (there often aren't any like you have with steels), but the time-temperature relationships for various precipitates. Since many precipitates are deleterious to one or more properties, it is important to understand how they can evolve during processing and later in service.
The text by Dupont, Lippold & Kiser has some discussion on precipitation and strain aging cracking in Waspaloy (but no TTT diagram).
"Everyone is entitled to their own opinions, but they are not entitled to their own facts."