In-layer radiometry and high-resolution autoradiography were used to examine the self-diffusion along the internal interfaces in the single crystal ingots of Ni3Al-based superalloy obtained by high-gradient or low-gradient solidification. The permeability, by diffusion, of the interfaces was measured at 700 to 900C and the activation energies were calculated. The structure of the primary precipitations was examined through electron microprobe analysis and the precipitated phases were identified. The effect of the temperature gradient of solidification on the diffusion parameters was discussed. Ni3Al-based (alloyed) intermetallide (ordered γ′ phase) was known as the general strengthening phase in the modern nickel-based superalloys. Increasing the phase fraction and making the phase chemistry more complex and favorable were the very means that to a large extent had controlled improvement of the service characteristics of the superalloys during their 50-year history.Self-Diffusion of Nickel on the Internal Interfaces in a Superalloy Based on Multialloyed Ni3Al Intermetallide. Aristova, E.Y., Belova, E.N., Bondarenko, Y.A., Buntushkin, V.N., Ginsburg, S.S., Kablov, E.N., Nefedov, V.G., Razumovskii, I.M.: Russian Metallurgy, 1996, 3, 83-9

Table 32

Bulk diffusivity of 63Ni in B-doped Ni3Al