Line-broadening of Mössbauer resonance was used to study in the γ phase at 1200 to 1390C. The results could be described by:

D (m2/s) = 1.5 x 10-4 exp[-3.1(eV)/kT]

A.Heiming, K.H.Steinmetz, G.Vogl, Y.Yoshida: Journal of Physics F, 1988, 18[7], 1491-503