Serhii Bobyr1, Martin Sahlberg1, Joakim Odqvist2, 1Uppsala University, Ångström Laboratory, Lägerhyddsvägen 1, Box 538, SE 751 21, Uppsala, 2KTH Royal Institute of Technology, Department of Materials Science and Engineering, Brinellvägen 23, SE-100 44, Stockholm, Sweden
Diffusion is the most important transfer processes of substances and masses in metals. The theory of diffusion in metals is based on the fundamental concepts of physical kinetics and is very important branch in Material Science. The purpose of this project is to develop a statistical thermodynamic model for the self-diffusion in metals and to apply it for calculating the diffusion coefficients of atoms in metals and alloys. The relationship between the diffusion flux of vacancies and the gradient of their chemical potential has been obtained from the basic principles of statistical thermodynamics. For a solid solution of vacancies in a metal, an expression for the self-diffusion coefficient has been found. To calculate the activation energy of self-diffusion in metals and simple alloys, the statistical calculation model (SCM) was proposed that consider energy calculations from first principles, statistical processing of experimental data on self-diffusion of metals, and a physicochemical model using the correlation relationship between the activation energy of self-diffusion and the melting temperature of metals. The calculations are compared with the known experimental data on the diffusion in iron and other metals with a good agreement between the results. Based on the processing of experimental results on diffusion in metals using SCM, thermodynamic parameters of self-diffusion activation energies in a- and ?-Fe, Ti, V, Mo, W, Ag, Cu and other metals were established. The SCM for self-diffusion in metals and simple alloys was implemented in the corresponding database, including 43 base metals and silicon.
metals; statistical thermodynamics; self-diffusion; vacancies; pre-exponential factor; activation energy.
