The diffusive behavior of Al in 6N-purity material was studied at 240 to 550C. The results could be described by:

D (cm2/s) = 3.5 x 10-2 exp[-28.75(kcal/mol)/RT]

F.Y.Fradin, T.J.Rowland: Applied Physics Letters, 1967, 11[6], 207-9