Diffusion in the γ'-phase was investigated at 1423 to 1523K by using pseudo-binary diffusion couples. It was found that the concentration gradient of Re appeared to promote up-hill diffusion of Al. The cross interdiffusion coefficient, DAlReNi, was independent of matrix ordering since it was qualitatively comparable between those in the γ'-Ni3Al and γ-Ni phases. The tracer diffusion coefficient for Re in Ni3Al was estimated by extrapolation, and the activation energy was consistent with the site preference of the element. The diffusivity in the γ’ phase could be described by:

D(m2/s) = 1.5 x 101exp[-467.5(kJ/mol)/RT]

These results suggested that the diffusion of Re was controlled mainly by the formation of antisite defects in the Ni sub-lattice, with a negligible contribution from the antisite bridge mechanism.

E.Mabruri, S.Sakurai, Y.Murata, T.Koyama, M.Morinaga: Materials Transactions, 2008, 49[6], 1441-5