Data on Nb diffusion at 1200 to 1500K were obtained by using electron probe microanalysis. It was found that the temperature dependence of the diffusivity could be described by:

D(cm2/s) =1.04 x 10-2exp[-48.2(kcal/mol)/RT]

It was shown that the diffusivity of Nb was almost an order of magnitude higher than the self-diffusion of Ni. It was concluded that the large difference (78.31kJ/mol) in the activation energies reflected the existence of a rather large impurity-vacancy binding energy.

R.V.Patil, G.B.Kale: Journal of Nuclear Materials, 1996, 230[1], 57-60