Papers by Keyword: Nanosegregation

Abstract: Despite nanosegregation of solutes at grain boundaries has been intensively studied in the past decades and numerous theoretical data as well as experimental values on characteristic energies and/or enthalpies and entropies exist some questions remain still unanswered. In this paper some of these questions – Which energetic quantities obtained in different ways, experimentally and theoretically, can be mutually compared What is the segregation site of a solute in the grain boundary core – are discussed in more detail. It will be shown that the entropy of grain boundary segregation plays an important and indisputable role in responding some issues and that understanding of its role will help us to elucidate fundamentals of the grain boundary segregation.

Abstract: An annotated analytical essay of possible nanofabrication and nanotechnology applications is presented with respect to: (1) some techniques and original results [1-4] concerning the regularities and micromechanisms (physics) of the hydrogen fluoride gas activator influence on the diffusion-controlled oxidation processes of titanium, zirconium and zirconium-based alloys with niobium, and also – on nitriding, boriding and carbiding a series of refractory metals (Ti, Zr, Nb, Mo, W, Ta); (2) some techniques, original results and physics of the diffusion-controlled formation processes of the compound-like nanosegregation [5-13] and the results [13-23] on the liquid-like phase at grain boundary regions in metals and alloys. In the scope of this review, a constructive analysis, the Arrhenius-type treatment, and the original data interpretation [16-21] has been carried out for the first time; (3) some techniques, original analytical results, and physics [24, 25] of the diffusion-controlled processes of the hydrogen multilayer intercalation (physisorption of a condensation or clustering type) with carbonaceous nanostructures. The main objective of the given analytical essay is to attract the researchers’ attention to the expediency of such a non-conventional data analysis and interpretation.

Abstract: New possible nanotechnology applications of some original developments and results of studying the regularities and micromechanisms (physics) of the hydrogen °uoride gas activa- tor in°uence on oxidation of titanium, zirconium and zirconium-based alloys with niobium, and also - on nitriding, boriding and carbiding a series of refractory metals (Ti, Zr, Nb, Mo, W, Ta) are elaborated. The new possible nanotechnology applications of the techniques and physics of creating a compound-like nanosegregation or the liquid-like nanosegregation at grain bound- aries in nanostructured metals, i.e. creating of speci¯c cellular type natural nanocomposites, are considered as well.

Abstract: Specific phase transitions to the compound-like impurity nanosegregation structures at dislocations and grain boundaries in metals and their influence on diffusion-assisted processes are considered, mainly, on the basis of the thermodynamic analysis of the related experimental data. The following systems and aspects are in detail considered: (1) the hydride-like nanosegregation of hydrogen at dislocations and grain boundaries in palladium and their influence on the apparent characteristics of hydrogen solubility and diffusivity in palladium; (2) the physics of the anomalous characteristics of diffusion of Fe and other transition impurities in crystalline Al at elevated temperatures, the role of the compound-like nanosegregation (CLNS) of Fe and the others at dislocations and grain boundaries in Al, analysis of the Mössbauer and diffusion data on CLNS of Fe at grain boundaries and dislocations in Al; (3) some new physical aspects of internal oxidation and nitridation of metals (for Cu-0.3%Fe alloy/Cu2O surface layer, and for (Ni-5%Cr) alloy / N2 gas), the role of the compound-like impurity nanosegregation at dislocations and grain boundaries, study results on the deviations from the classical theories predictions and their interpretation. The possibility is considered of nanotechnology applications of the study results for creation of nanostructured metals with compound-like nanosegregation structures at grain boundaries, in order to obtain specific physical and mechanical properties of such a cellural-type nanocomposites. In particular, it can be complex hydride-like, carbide-like, nitride-like, carbide-nitride-like, oxide-like or intermetallide-like nanosegregation structures at grain boundaries of nanostructured metals.