Manganese diffusion in chromia was studied in polycrystals and oxide films formed by the oxidation of Ni-30Cr alloy at 700 to 1100C under an O pressure of 10-4atm. After depositing Mn onto the chromia surface and diffusing, the Mn penetration profiles were determined by means of secondary ion mass spectrometry. In all cases, the diffusion profiles exhibited 2 domains. In the first domain, using the solution of Fick's law for diffusion from a thick film into a semi-infinite medium, the bulk diffusion coefficients were determined. In the second domain, use of the LeClaire model permitted the grain boundary diffusion parameter to be obtained. The Mn diffusion did not depend significantly upon the nature or microstructure of the chromia. The activation energy for grain boundary diffusion was not very different from that obtained for bulk diffusion; due probably to segregation phenomena.

First Study of Manganese Diffusion in Cr2O3 Polycrystals and Thin Films by SIMS. A.C.S.Sabioni, A.M.Huntz, L.C.Borges, F.Jomard: Philosophical Magazine, 2007, 87[12], 1921-37