The diffusion of C atoms between the bulk and (100) surface was studied directly between 1400 and 2000K for the first time. The difference in the activation energies of C dissolution and precipitation was found for the case where the diffusion fluxes of dissolved and precipitated C atoms were in equilibrium. This difference defined the enrichment of the surface by C, relative to the bulk. The experimentally found activation energy for C dissolution was 3.9eV. The activation energy for C precipitation was estimated to be 1.9eV. The latter value was close to the energy for bulk C diffusion in Mo.

Carbon Diffusion between the Volume and Surface of (100) Molybdenum. N.R.Gall, E.V.Rutkov, A.Y.Tontegode: Technical Physics, 2002, 47[4], 484-90