Direct experimental study of the equilibrium diffusion of carbon atoms between the (100)Mo surface and the bulk

A direct experimental study of the diffusion of carbon atoms between the (100)Mo surface and the bulk has been carried out at process temperatures in the range $1400$–$2000$ K, and the total balance of carbon atoms in the system has been determined. The difference in the activation energies of carbon dissolution and precipitation $\Delta E=E_{S1}-E_{1S}$ has been found under conditions of a dynamic equilibrium between both processes. This difference determines the temperature dependence of the degree of surface enrichment with carbon in reference to the bulk. The activation energy of the dissolution of carbon atoms has been determined in special experiments ($E_{S1}=3.9$ eV), and the activation energy of the precipitation of carbon atoms $E_{1S}$ has been calculated ($E_{1S}=1.9$ eV), which turns out to be close to the energy of carbon bulk diffusion in molybdenum.