Part of the book: Titanium Alloys
Nuclear power engineering development is held back by both the nuclear reactor safety reasons and the problems related to creating materials suitable for using in the reactors. These materials must be resistant to radiation, able to stand high temperatures, and stable to the corrosive environments. In this work, the general regularity of the interstitial atoms and vacancy interaction with impurity substitutional atoms of 57Co(57Fe) in bcc lattice metals has been systematically investigated for the first time. The electron states and structure of "impurity-interstitial” atom, "impurity-vacancy" systems, and their mössbauer parameters are defined. For the first time, by the Mössbauer effect study, the complexes annealing stages from isochronal annealing temperature have been defined. The mössbauer imputity atoms vibrations rms amplitude values and their binding energy are determined. It has been experimentally established that atom mobility considerably increases in radiation-damaged zones created by high-velocity charged particles, fission fragments, or ionized displaced atoms. The compound dumbbell state in bcc metals was investigated, and it was shown that unlike fcc metals, in the bcc metals the considerable quadrupole splitting was revealed, which enables us to separate them on different interstitial configurations around 57Co impurity. It was also established that non-cubic charge distribution around a mössbauer atom leads to the electric field gradient that causes the nuclear levels hyperfine splitting owing to quadrupole interaction.
Part of the book: New Trends in Alloy Development, Characterization and Application
This chapter deals with the experimental research and computer simulation of low- and medium-energy (E 0 = 1-30 keV) ion collisions on the surface of a solid and of the accompanying effects, namely scattering, sputtering, and surface implantation. Experimental and computer simulation studies of low-energy (Е 0 = 80–500 eV) Cs+ ions scattering on Ta, W, Re target surfaces and K+ ions scattering on Ti, V, Cr target surfaces have been performed for more accurate definition of mechanism of scattering, with a purpose of evaluation of use of slow ions scattering as a tool for surface layer analysis. The peculiarities of the process of correlated small angle scattering of 5–15 keV He, Ne, Ar, Kr, Xe, and Rn ions by the Cu(100), Ni(100), and V(100) single-crystal surfaces have been investigated by computer simulation. It has been shown that under these conditions the inelastic energy losses become predominant over the elastic ones. The anomalous energy losses observed experimentally at the grazing ion scattering by the single-crystal surface were explained. It has been shown by computer simulation that the peculiarities of the chain effect at direct and reverse relation of masses of colliding particles and rainbow effect at quasi-single and quasi-double scattering of ions, heavier than adatoms, lead to the appearance of characteristic peaks in the energy and angular distributions of scattered ions. Analysis of these peaks and comparison with experiment give an opportunity to control the initial stages of adsorption and identification of adsorption structures with the help of low-energy ion scattering. It has been shown that from the correlation of the experimental and calculated energy distributions of the scattered particles, one may determine a spatial extension of the isolated atomic steps on the single-crystal surface damaged by the ion bombardment. Results obtained can be also used to study short-range order in alloys undergoing ordering. Grazing ion-sputtering processes of Si(001), SiC(001), and Cu3Au(001) surfaces at 0.5–5 keV Ne+ bombardment have been studied by computer simulations. A preferential emission of Cu atoms in the case of Cu3Au (001) surface sputtering is observed. It was shown that in the case of grazing ion bombardment, the layer-by-layer sputtering is possible, and its optimum is observed within the small angle range of the glancing angles near the threshold sputtering angle. The peculiarities of trajectories, ranges, and energy losses of low-energy different-mass ions channeling in thin single crystals of metals and semiconductors have been thoroughly studied by computer simulation. It has been found that in the case of light ions, even at low energy, the main contribution to energy loss is made by inelastic energy losses, whereas for heavy ions, already at E < 10 keV, elastic energy losses exceed inelastic ones. Profiles of the distribution of channeled ions have been calculated depending on the crystal lattice type, kind of ions, and their energy. It has been shown that the channeling of low-energy ions through thin single-crystal metal films can be used to determine the sort and adsorption site of light atoms adsorbed on a clean rear surface.
Part of the book: Radiation Effects in Materials