It was found that the data for 1100 to 1400C could be described by:

D (cm2/s) = 2.61 x 10-2 exp[-16.7(kcal/mol)/RT]

J.Gerlach, F.Heisterkamp, H.G.Kleist, K.Mager: Metall, 1966, 20, 1272-8