By analyzing the evaporation kinetics of Al from Ta alloys which contained 0.0027 to 0.0067at%Al, at 1700 to 2000K, it was deduced that the Al diffusivity was described by:

D (cm2/s) = 1.5 x 100 exp[-73.1(kcal/g-atom)/RT]

G.I.Nikolaev, N.V.Bodrov: Zhurnal Fizicheskoi Khimii, 1978, 52[6], 1430-3