The self-diffusion of 63Ni along boundaries in Ni-24.9Al-4.8at%W was investigated by using radiotracer and serial sectioning techniques. By using the near-surface parts of the profiles, which reflected lattice diffusion, the volume diffusion coefficients were estimated. In the case of pure Ni3Al, the agreement of the high-temperature results with published data was good. By using the bulk diffusion results, and by analyzing the tails of the measured profiles, grain-boundary diffusivities were calculated for 1373 to 1023K. It was found that these could be described by the relationship:

D (m3/s) = 3.3 x 10-12 exp[-217(kJ/mol)/RT]

N.P.Zulina, E.V.Bolberova, I.M.Razumovskii: Acta Materialia, 1996, 44[9], 3625-31