The study of diffusion of hydrogen atoms in the crystal lattice of fcc metals Pd, Ni, Al, Ag was performed by the method of molecular dynamics. The diffusion characteristics of hydrogen impurity (activation energy of hydrogen atom migration and pre-exponential factor in the Arrhenius equation) in the considered metals were calculated. It is shown that the prevailing mechanism of the over-barrier hydrogen diffusion in fcc metals consists of successive migration through octahedral and tetrahedral pores. During migration, as a rule, the hydrogen atom is not delayed in tetrahedral pores.

Self-diffusion in liquid and solid alloys of the Ti–Al system, including pure Ti and Al metals, is investigated using the molecular dynamics method. Apart from intermetallides Ti₃Al, TiAl, and TiAl₃, disordered alloys with analogous ratios of the components are considered. For these systems, self-diffusion characteristics are obtained separately for Ti and Al atoms. According to obtained results, the diffusion activation energy of both liquid and solid alloys of the Ti–Al system considerably depends on the concentration of components, repeating approximately the phase diagram. The activation energy of disordered alloys turns out to be smaller by 1.5 times than that for ordered alloys. No appreciable difference in the diffusion mobilities of atoms of different species is detected in analysis of self-diffusion in melts and in solid disordered alloys. However, in the case of ordered alloys (especially intermetallides Ti₃Al and TiAl), this difference is manifested clearly: Al atoms diffuse much more slowly than Ti atoms. Diffusion in intermetallide TiAl₃ is anisotropic: main displacements of atoms occur along atomic planes with alternating Ti and Al atoms in the D0₂₂ superstructure packing.

The contributions of different mechanisms of self-diffusion in face-centered cubic metals Ni, Cu, and Al at thermodynamic equilibrium have been analyzed using the molecular dynamics method. The vacancy, divacancy, and cyclic mechanisms of self-diffusion, as well as the mechanisms involving the vacancy migration to the second coordination sphere and the formation and recombination of Frenkel pairs, have been considered. It has been shown that the second in contribution to the self-diffusion after the vacancy mechanism in the metals under consideration is the migration of divacancies. The third is the mechanism involving the formation and recombination of dynamic Frenkel pairs. The cyclic mechanisms (with simultaneous atomic displacements) and the vacancy migration directly to the second coordination sphere in face-centered cubic metals are unlikely.

The migration of the 〈100〉 and 〈111〉 tilt boundaries in Ni and the Ni3Al intermetallic compound is studied by molecular dynamics simulation. The low-angle 〈100〉 boundaries in Ni and Ni3Al...