The Growth kinetic of γ̍ Precipitations in cold rolled Waspaloy

The effect of temperatures and times of aging heat treatment on the characteristics and growth kinetic of γ̍ Precipitations were investigated in cold rolled Waspaloy superalloy, in this article. The 1 mm cold rolled strap were stabilized at 845 ˚C and then the samples were aged at 730, 460 and 800 ˚C until 23 hours. The microstructure of samples especially γ̍ phases were assessed with optical and scanning electron microscopy. The volume fraction and size of γ̍ particles were measured and analyzed. The microstructural and data analysis results showed that the growth kinetic of γ̍ Precipitations obey the LSW theory and the particle growth controlled via volume diffusion and coalescence of precipitates. The measured activation energy of γ̍ Precipitations that is thermally activated is 265 kJ/mol. This value is about equal to activation energy for diffusion of Al and Ti in FCC Ni that are 270 and 256 kJ/mol, respectively.