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) = 4.0 x 10-4 exp[-304(kJ/mol)/RT]

Heavily alloying γ-TiAl with 10at%Nb significantly increased the Ti 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