Спектрально-люминесцентные свойства кристаллов ZrO-=SUB=-2-=/SUB=--Sc-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=--Tb-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

Crystals of the concentration series ZrO2- (8-10) mol.% Sc2O3- (1-2) mol.% Tb2O3 were grown by the method of directional crystallization of the melt from a cold container. Analysis of the spectral-luminescence characteristics of these crystals after growth and after annealing processing in a vacuum revealed the presence of both Tb3 + and Tb4 + ions in them. In crystals ZrO2- (8-10) mol.% Sc2O3- (1-2) mol.% Tb2O3, the presence of a process of non-radiative energy transfer from Tb4 + ions to Tb3 + ions was revealed.

Surface-barrier structures based on solid solutions (In 2 S 3 ) х •(AgIn 5 S 8 ) 1–х

Single crystals of solid solutions (In2S3)x⋅ (AgIn5S8)1–x were grown by the method of directional crystallization of the melt (Bridgman method). Studies of the elemental composition and crystal structure of these single crystals have been carried out. On the basis of solid solutions (In2S3)x⋅ (AgIn5S8)1–x, photosensitive structures have been created for the first time and the photoelectric properties of these structures have been determined. The possibility of using the created structures as broadband photoconverters of optical radiation is shown.

Predicting the properties of nickel-based superalloys directional crystallization

The aim of this work is to obtain predictive regression models, with which it is possible to adequately calculate the mechanical properties of heat-resistant nickel alloys, without prior experiments. Industrial alloys of directional crystallization of domestic and foreign production were selected for research. The values were processed by the method of least squares to obtain correlations with the receipt of mathematical equations of regression models that optimally describe these dependencies. As a result of processing of experimental data, the ratio of alloying elements which can be used for an estimation of mechanical properties taking into account complex influence of the main components of an alloy is offered for the first time. Since the dimensional mismatch of the lattice parameters is associated with the degree of concentration of solid-soluble hardening of γ- and γ'-phases, the efficiency of dispersion hardening of the alloy, creep rate and other properties, the obtained ratio allows to link these properties with multicomponent systems. Regression models are presented, with the help of which it is possible to calculate dimensional mismatch, strength, heat resistance, number of  phases and density of alloys with high accuracy. The regularities of the composition influence on the properties of heat-resistant nickel alloys of directional crystallization are established. It is shown that for multicomponent nickel systems it is possible to predict with high probability misfit, which significantly affects the strength characteristics of alloys of this class. The decrease in the value of misfit is accompanied by an increase in the solubility of the elements in the -solid solution at a value of the ratio of alloying elements of 1.5 - 1.6. However, an increase in the ratio of alloying elements greater than 2 is accompanied by an increase in misfit, because the -solid solution has reached a maximum of dissolution. The perspective and effective direction in the decision of a problem of forecasting of the basic characteristics influencing a complex of service properties of alloys both at development of new heat-resistant nickel alloys, and at perfection of structures of known industrial marks of this class is shown. Keywords: nickel-based superalloys, dimensional mismatch (γ / γ'- mismatch), strength, heat resistance.

Unidirectional crystallization and 3D structure of ternary four-component eutectic of B4C-NbB2-SiC system

Purpose. To investigate the laws of crystallization and formation of 3D morphology of ternary eutectics in system B4C-NbB2-SiC. Research methods. SEM (SE, BSE), РСМА (EDS, WDS), XRD. Results. The micro- and macro-morphology of eutectic colonies in alloys of the system NbB2-SiC-В4С formed during directional crystallization have been investigated. The obtained patterns are embodied in a 3D structural model of (B4C+NbB2+SiC) eutectic cell and from these result, a microscopic kinetics of crystallization of this cell was proposed. The continuity of eutectic phase dendrites from nucleation to the end of growth and inadequacy of ideas about eutectic as a mechanical mixture of small crystals of eutectic phases were shown. Scientific novelty. For the first time a 3D model of a three-phase 4-component eutectic cell of eutectic colony was built. For the first time the possibility of combined microscopic crystallization kinetics of a three-phase eutectics was revealed, including both paired cooperative microscopic kinetics of (SіC+ NbB2) growth and the kinetics of autonomous growth of the third eutectic phase B4C. Practical value. Revealing the pattern of micro and macrostructure formation of a three-phase eutectics, which was formed in the course of directional crystallization, opens up technological prospects for purposeful control of the structure and properties of eutectic alloy due to the change of micro and macro morphological constituents, including the method of modification.

Production of single-crystal seeds [001] from nickeltungsten alloys by directional crystallization

The problem of obtaining priming materials from Ni-W alloys arose in connection with the development of technology for casting single-crystal turbine blades of gas turbine engines (GTE) from hightemperature alloys. This technology uses a seed method for producing single-crystal castings with a crystallographic orientation [001] using seedings from alloys of the Ni-W system with a melting point 120–140°C higher than the casting alloy. The use of such primers greatly simplifies the casting process of turbine blades with a single-crystal structure, increases its reliability both in pass-through furnaces of the PMP-2 type and in high-gradient furnaces of the UVNK-9A type. The article presents the results of the study of the influence of temperature-velocity parameters of directional crystallization, namely, the temperature gradient GZ on the structure of the obtained single-crystal seed blanks, as well as the study of effects of tungsten and carbon on the structure of single-crystal seed blanks, and makes recommendations for optimizing the technological process of single-crystal casting of Ni–W seed blanks adjusting the alloy composition for the seed blanks.