The changes in the vibrational energies and the signs of changes in the interatomic spacings upon the formation of vacancies in the bulk of metal and in the cores of the crystallite-conjugation regions in polycrystalline transition metals with body-centred cubic and face-centred cubic lattices were determined. The vibrational energy increased upon the formation of a vacancy in the bulk because of a positive relaxation contribution to the change in the force constant of the atoms surrounding a vacancy. Positive relaxation contributions to changes in the force constants and to a corresponding increase in the vibrational energy of the atoms surrounding a vacancy also arose upon the formation of so-called split vacancies in the cores of crystallite-conjugation regions of polycrystalline transition metals with a face-centred cubic lattice. The positive relaxation contributions to the changes in the force constant of atoms in the region of localization of split vacancies were caused by a decrease in the interatomic spacings upon formation, just as in the formation of conventional vacancies in the bulk. The vibrational energy of the immediate environment of vacancies that formed in the crystallite-conjugation region cores in polycrystalline d transition metals with a body-centred cubic lattice decreased because of a negative relaxation contribution to the change in force constants. The cores of the high-angle crystallite-conjugation regions in polycrystalline d transition metals with a body-centred cubic lattice were characterized by a negative internal pressure. Therefore, vacancies with positive relaxation volumes υBCC > 0 were formed in them, causing an increase in the interatomic distances in the nearest environment of such vacancies.

Changes in the Vibrational Energies and Interatomic Spacings upon the Formation of Vacancies in the Volumes and in the Cores of Crystallite-Conjugation Regions of Polycrystalline Transition Metals with Cubic Lattices. S.M.Klotsman, A.N.Timofeev: Physics of Metals and Metallography, 2008, 105[1], 10-8