The diffusion of C atoms between the volume and the surface of (100) Mo was directly studied between 1400 and 2000K (i.e., at process temperatures) for the first time. The balance of C atoms in the system was determined. The difference in the activation energies of C dissolution and precipitation, ΔE = Es1 – E1s, was found for the case when the diffusion fluxes of dissolved and precipitated C atoms were in equilibrium. This difference defines the enrichment of the surface by C relative to the bulk. The experimentally found activation energy of C dissolution was Es1 = 3.9eV. The activation energy of C precipitation was estimated at E1s = 1.9eV. The latter value was close to the energy of bulk diffusion of C 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