The diffusion of Nb was analyzed via in-depth profiling using secondary ion mass spectrometry. The Nb diffusivity was lower, by about an order of magnitude, than that for self-diffusion. The data could be described by:

D (m2/s) = 3.15 x 10-4 exp[-338.7(kJ/mol)/RT]

It was concluded that Nb diffusion occurred substitutionally via thermal vacancies in the Ti sub-lattice.

J.Breuer, T.Wilger, M.Friesel, C.Herzig: Intermetallics, 1999, 7[3-4], 381-8