Tracer/sectioning techniques were used to study the diffusivity of 60Co in single crystals of α-type material at 871 to 1145K. It was found that the diffusivity of Co was some 5 orders of magnitude more rapid than that of Ti. On the basis of the data, it was concluded that diffusion parallel to, and perpendicular to, the c-axis could be described by:

parallel:     D (cm2/s) = 1.9 x 10-2 exp[-27.2(kcal/mol)/RT]

perpendicular:     D (cm2/s) = 3.2 x 10-2 exp[-30.0(kcal/mol)/RT]

It was suggested that an interstitial-type mechanism was operating.

H.Nakajima, M.Koiwa, Y.Minonishi, S.Ono: Transactions of the Japan Institute of Metals, 1983, 24[10], 655-60