Diffusion in Ti–54Al–10at%Nb was investigated over a wide temperature range by using radiotracer techniques. Sectioning was performed by grinding or sputtering in order to measure the tracer diffusivities at high and low temperatures, respectively. An almost linear Arrhenius dependence was found:

D (m2/s) = 1.9 x 10-5 exp[-280(kJ/mol)/RT]

Heavily alloying γ-TiAl with 10at%Nb significantly increased the Nb diffusivity. This was attributed to elastic distortion of the L10 structure of TiAl, induced by the over-sized Nb atoms, which decreased the activation barriers for atomic diffusion.

S.Divinski, F.Hisker, C.Klinkenberg, C.Herzig: Intermetallics, 2006, 14[7], 792-9