Diffusion measurements were performed at 870 to 1100K, parallel or perpendicular to the c-axes of monocrystalline samples of the -phase. The diffusion profiles were determined by means of secondary ion mass spectrometry. It was found that the diffusivity in high-purity material could be described by:

D (cm2/s) = 1.0 x 10-1 exp[-3.0(eV)/kT]

The parallel/perpendicular diffusion anisotropy ratio was less than unity for the high-purity material.

G.M.Hood, H.Zou, J.A.Roy, R.J.Schultz, N.Matsuura, J.A.Jackman: Journal of Nuclear Materials, 1996, 228[1], 43-6