Precipitation in Spray-Formed in 718

Abstract

The precipitation of the y', y" and 6 phases in a spray-formed version of IN 7 18 has been studied by hardness measurement and metallographic examination of samples subjected to solution treatment at 1025C followed by isothermal treatments between 620 and 1010C up to 100 h. The precipitation processes were compared to those in a wrought (ring-rolled) version of the alloy subjected to the same heat treatments. Time-temperature-hardness diagrams for the two alloys were constructed. Small differences were observed between the two materials but these can at least partly be attributed to differences in composition. For the spray-cast material the &phase solvus temperature was determined and the growth kinetics of the y" phase established Suprralloys 71 8. 625. 706 and Various Derivati~cs