Vladimir D. Klopotov

Structure-phase states in the Cu-Pd-Pt system

A three-dimensional diagram of the structural states in the Cu-Pd-Pt system is formulated using literature data, by geometric construction of multicomponent phase diagrams on the basis of topological principles. Regions of relatively unstable (pretransition) long-period structural-phase states containing nanostructural elements are present in the resulting diagram, in temperature-composition space. The prediction of promising nanostructural functional materials is considered.

Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen’s law.

New organo-mineral peat-based admixtures for cement compositions

The paper proposes a synthesis method of a new effective organo-mineral admixture for cement systems. The study of the admixture production modes at 600 °C and 400 °C in conditions of limited air access is described. It is shown that introduction to the cement system of the peat-based admixture produced at 600 °C allows to achieve a significant improvement in the strength and hydro-physical properties of the cement stone. It is established that the optimal peat processing temperature for production of modifying admixtures is nearly 600 °C. The results of the X-ray phase analysis showed that the product, formed during peat processing at 600 °C, contains in its structure various phases in a nanodispersed state, including fullerenes and other types of nanocarbon. It is shown that the presence of nanocarbon particles change the kinetics and the mechanism of cement and water interaction and, as a consequence, lead to an increase in the strength, water-resistance, and frost-resistance of the cement stone.

Binary phase diagrams based on elements VIIIA and IB periods of the D.I. Mendeleev’s table and features of crystallographic parameters

The data obtained as a result of the analysis of crystallogeometric parameters and the structure of state diagrams of binary systems from elements VIIIA and IB periods of the D.I. Mendeleevs table are presented. It is shown that the classification of the evolution of phase diagrams of binary systems by types, proposed by T.A. Lebedev, correlates with features of concentration dependences of the deviation of atomic volumes in solid solutions from Zen law.

Evolution of the Entropy of Dislocation Structures with Strain in Solid Solutions of Cu-0.5at.% Al

The study on the evolution of the dislocation structure (DS) parameters with strain of solid solutions of Cu-0.5 at.% Al at different test temperatures has been carried out. It has been shown that in substructures with a disordered type of DS (disorder), the disordered mixtures with non-disoriented cells, as well as mixtures of non-disoriented and disoriented cellular structures, the entropy density increases with strain. It has been shown that formation of the cellular substructure corresponds to a diffuse kinetic phase transition of the 1-st kind in the DS. A jump-like decrease in entropy accompanying this phase transition is associated with the annihilation of dislocations in cellular walls and formation of excess dislocation density.

Structural-and-phase states, crystallogeometric and crystallochemical parameters of membrane palladium-based alloys

The results of the analysis of the ordered phase equilibria in binary Cu-Ni, Cu-Pd, and Ni-Pd, and ternary Cu-Ni-Pd systems are presented. It has been established that the packing index in disordered solid solutions of binary systems Cu-Ni, Cu-Pd, and Ni-Pd is close to the value of 0.74, and is accompanied by an insignificant deviation from the Zen law of concentration dependences of atomic volumes. A significant decrease in the packing index has been observed in the ordered phase with a B2 structure in the range of 40 at.% Pd in alloys of the binary system Cu-Pd. The correlation between the jump in hydrogen-permeability and the change in the effective size of atoms-components has been revealed. This phenomenon manifests itself in a significant decrease in the packing index in the ordered phase with a B2 structure in the range of 40 at.% Pd.

Long-period structure in Cu–Pd–Me and Ti–Al–Me metallic alloys

Analysis of the phase diagrams of Cu–Pd–Me systems (Me = Ag, Au, Ni, Pt, Ga) shows that introducing gold and palladium atoms in alloys of stoichiometric composition CuPd and Cu3Pd may give rise to extensive regions of homogeneity of phases with long-period structures after the appropriate heat treatment. In Ti–Al–Me systems (Me = V, Cr, Mn, Mo, Nb, Cu), the regions of homogeneity of Al3(Ti, Me) phases with long-period structures with D022 structure become smaller in the following sequence: V → Mo → Nb → Cr → Mn → Cu.

Phase Formation in the Ti-Y-O System Formed Using High-Energy Methods

A surface alloy of the yttrium/titanium system, enriched with oxygen atoms, has been developed using high-energy methods. Formation of a multilayer multiphase submicron-and nanoscale structure has been revealed. A substantial increase in the microhardness (by ≈3 times), a decrease in the friction coefficient (more than by 2 times) and the wear rate (by ≈3 times) of the doped layer have been revealed.

Crystallographic parameters of compounds and solid solutions in binary systems Cu-Pt and Ga-Pt

The study establishes that the packing index in compounds of the system Cu-Pt is close to the value 0.74 against a slight deviation from the Zen law of atomic volumes. The compounds in the system Ga-Pt have the highest values of the packing index in the range of the equiatomic composition, which greatly exceed ψ for close-packed structures based on FCC and HCP lattices for compounds made of the same kind of atoms. A correlation between singular points on the phase diagram of the system Ga-Pt and high values of the packing index in compounds is established.

Phase stability in binary palladium alloys

The phase equilibria of ordered phases in Pd-Me binary systems (where Me = Co, Rh, Ir, Cu, Ag, Au, Ni, or Pt) are analyzed, so as to find correlations among the crystal-chemical and crystal-geometric factors. The packing coefficient for disordered solid solutions in such palladium-based binary systems is close to 0.74, against the background of slight deviation of the atomic volume from Zen’s law. The increase in the hydrogen permeability in Cu-Pd binary alloys is found to correlate with considerable decrease in the packing coefficient for ordered B2 phase close to 40 at % Pd. In Pd-Me binary systems, with certain combinations of temperature and dimensions, different structural and phase states are formed. When the results are plotted in coordinates of the temperature factor and the dimensional factor, three regions are seen. On that basis, the structural and phase states may be classified as a function of the ratio between the temperature and dimensional factors in palladium-based binary systems. Region I corresponds to systems that only form solid solutions; region II to systems where ordered phases are formed from the solid solution; and region III to compounds in which the solid solutions are stratified.