Volume, grain boundary and phase boundary Ni self-diffusion in Ni3Al-based alloys with Cr, Mo, Hf, Ta and with B were studied at 750 to 1100C. The sectioning technique followed by autoradiography was used for determination of the concentration profiles. The diffusion data obtained prove that in the range of 750 to 950C, intercrystalline boundaries made a dominant contribution to the overall diffusion flow. The grain boundary diffusion coefficients were 4 to 5 orders higher than the bulk ones, and the activation energy was 25 to 30% lower. The phase boundary diffusion coefficients were 3 to 4 orders higher than the bulk ones, and the activation energy was 10% lower. An increase in the aluminium content resulted in a decrease in the diffusion permeability of both grain and phase boundaries.

Ni Self-Diffusion in Alloyed Ni3Al. Bokstein, B.S., Bokstein, S.Z., Spitsberg, I.T.: Intermetallics, 1996, 4[7], 517-23