The evolution of delta-phase in a superplastic Inconel 718 alloy

An Inconel 718 sheet alloy was tested in tension at a temperature of 965 C and an initial strain rate of 10–4 s–1 corresponding to the conditions for optimum superplastic deformation. Detailed observations and quantitative measurements record the evolution of the d-phase during tensile deformation. The experiments show that the total precipitation of the d-phase increases with strain but there is a decrease with strain in the number density of the needle/plate d-phase particles and a corresponding increase with strain in the number density of the blocky/globular d-phase particles.