Diffusion of 44Ti and 63Ni in TiAl single crystal Original Research Article

Tracer diffusion of 44Ti and 63Ni in γ-TiAl has been investigated using single crystal samples by the ion-beam sputter-sectioning technique in the temperature range from 1133 to 1307 K and from 1053 to 1278 K, respectively. The tracer diffusion coefficients have been measured in the directions parallel and perpendicular to [001] axis. The diffusion of 44Ti in the direction perpendicular to the [001] axis is almost an order of magnitude faster than that parallel to the [001] direction. The cause of the anisotropy of the diffusion coefficient has been discussed in view of the defect structure and the correlation of the jump vectors of successive vacancy jumps. On the other hand, the anisotropy for 63Ni diffusion is less significant. It is suggested that Ni atoms diffuse more randomly in the two kinds of sublattices.