The results showed that C in solid solution could markedly decrease the grain boundary diffusivity in these alloys. It was suggested that caution should be exercised when relating the results of thin-foil experiments to bulk samples. This was because the kinetics of dislocation spreading had been shown to be slower in bulk samples as compared with thin foils. Although the calculated activation energies in thin-foil studies suggested that grain boundary diffusion predominated, it was thought to be possible that bulk diffusion played an important role in the deformation of bulk samples. Because different mechanisms could be rate-controlling in thin-foil and bulk samples, it might not be possible to correlate experimentally determined grain boundary diffusion parameters for thin foils and bulk samples.

J.L.Hertzberg, G.S.Was: Scripta Metallurgica et Materialia, 1995, 33[8], 1193-9