The migration of 57Co in monocrystals was studied, at 1680 to 2270K, by using a sectioning method which involved anodic oxidation. It was found that the data could be described by:

D (cm2/s) = 1.6 x 10-1 exp[-118.7(kcal/mol)/RT]

It was concluded that Co diffusion in W monocrystals was normal, and agreed with the pattern which was exhibited by the diffusion of W-series impurities. As a result, the diffusion was assumed to involve a monovacancy mechanism.

S.M.Klotsman, S.V.Osetrov, A.N.Timofeev: Physical Review B, 1992, 46[5], 2831-7

The best linear fits to the solute diffusion data ([5] to [25]) yield:

H (sd): Ln[Do] = 1.49E – 21 (R2 = 0.87); W(sd): Ln[Do] = 0.33E – 16.1 (R2 = 0.63)