Control of γ′ particle size and volume fraction in the high temperature superalloy Udimet 700

Experiments were conducted to determine the chemical composition, volume fraction and particle size of the γ′ precipitate in Udimet 700 as a function of temperature and time. Growth of the γ′ particles was found to followt ^1/3 diffusion controlled coarsening kinetics. The composition of γ′ varied only slightly with temperature and was independent of time. From this information, a method was developed to estimate the volume fraction and average particle size of the γ′ precipitate for any given heat treatment. It is suggested that this approach could be applied to other γ′ strengthened superalloys.