The migration of Zn was studied, at temperatures ranging from 180 to 235C, by measuring concentration profiles across grain boundaries which were essentially perpendicular to the surface of thick Al foils. The latter were coated with Zn and were annealed for a time which was sufficient to produce a steady flow of Zn, along the boundaries, from one side of the foil to the other. The Zn concentration was determined by carrying out energy-dispersive X-ray analyses in a transmission electron microscope. The results (table 26) could be described by:

D (cm2/s) = 0.018 exp[-112(kJ/mol)/RT]

and agreed well with the values which were obtained by extrapolating high-temperature data.

S.Varadarajan, R.A.Fournelle: Acta Metallurgica et Materialia, 1992, 40[8], 1847-54