The self-diffusion of 59Fe was measured, in the paramagnetic range, in alloys which contained between 1.5 and 12at%Si. The grain-boundary diffusion was characterized by a slight decrease in the diffusion parameters, in alloys which contained up to 2at%Si, followed by a regular increase:

1.48at%Si:     D (cm3/s) = 6.0 x 10-6 exp[-193(kJ/mol)/RT]

6.55at%Si:     D (cm3/s) = 2.8 x 102 exp[-334(kJ/mol)/RT]

8.64at%Si:     D (cm3/s) = 1.1 x 107 exp[-422(kJ/mol)/RT]

12.1at%Si:     D (cm3/s) = 7.3 x 106 exp[-413(kJ/mol)/RT]

The grain boundary diffusion behavior was not attributed to segregation effects, but to a possible change in the grain-boundary structure.

D.Treheux, L.Vincent, P.Guiraldenq: Acta Metallurgica, 1981, 29[5], 931-8