Theoretical study of interstitial atoms distribution in the bulk and at the surface of crystal. Surface segregation

Abstract

A theoretical investigation of diffusion, distribution and thermally activated redistribution of impurity interstitial atoms C (hydrogen, carbon) about the volume and surface both of crystalline films and massive crystals AB has been carried out. These crystals have bcc lattice and various types of free facets. The dependence of hydrogen and carbon filling of the surface and volume interstitial sites upon the films’ temperature and composition have been studied. Changing the temperature or pressure leads to the redistribution of C atoms in the system. The thermally activated processes of C atom redistribution among the volumetric and surface film interstices in AB alloy are investigated. The formulae for the equilibrium concentrations of interstitial atoms and the rate or relaxation time of interstitial atoms redistribution in dependence on concentrations of A, B alloy components, on long range order in A, B atoms distribution at the sites of crystal lattice, on temperature, on interaction energies of atomic pairs AC, BC are determined.