Phase relations in the CuI-SbSI-SbI3 composition range of the Cu–Sb–S–I quaternary system

The phase equilibria in the Cu-Sb-S-I quaternary system were studied by differential thermal analysis and X-ray phase analysis methods in the CuI-SbSI-SbI3 concentration intervals. The boundary quasi-binary section CuI-SbSI, 2 internal polythermal sections of the phase diagram, as well as, the projection of the liquidus surface were constructed. Primary crystallisation areas of phases, types, and coordinates of non- and monovariant equilibria were determined. Limited areas of solid solutions based on the SbSI (b-phase) and high-temperature modifications of the CuI (α1- and α2- phases) were revealed in the system. The formation of the α1 and α2 phases is accompanied by a decrease in the temperatures of the polymorphic transitions of CuI and the establishment of metatectic (3750C) and eutectoid (2800C) reactions. It was also shown, that the system is characterised by the presence of a wide immiscibility region that covers a significant part of theliquidus surface of the CuI and SbSI based phases

PHASE EQUILIBRIA IN THE NaCl–CaCl2–CaO SYSTEM

The phase equilibria of the ternary system CaCl2 – NaCl – CaO in the area which enriched of calcium and sodium chloride were investigated by the methods of differential-thermal analysis and powder X-ray phase analysis. In the systems were determined the equilibrium concentration of calcium oxide and the composition of the phases, which at the same time exist in an equilibrium state at different temperatures. The surfaces of liquidus and solidus were established, the compositions of the sections of the ternary system CaCl2–NaCl–CaO were defined, which recommended for electrochemical reduction of refractory metal oxides (titanium, zirconium and other), which allow electrolysis in the temperature range from 550 to 1000 °С. Five polythermal sections of the NaCl – CaCl2 – CaO ternary system were studied. For each polythermal section the regions of existence of the liquid and solid phases were established. For each polythermal section state diagrams were constructed. Used X-Ray phase analyses it was established the compositions of liquid and solid phases for each polythermal sections. The phases of which the system consists were determined. At a constant ratio of components [NaCl]:[CaCl2] = 1.06 (mol.) in the melts of the ternary system CaCl2 – NaCl – CaO, the equilibrium content of calcium oxide reaches 12.0 mol.%, while their crystallization temperature does not exceed 550 °C. This allows us to recommend mixtures of this composition for electrochemical reduction of refractory metal oxides in a wide range of temperatures (from 550 to 1000 °C) with a high content of both calcium and sodium chlorides (not less than 40 mol.%) and oxide. calcium (up to 12.0 mol.%). The eutectic of this ternary system has a melting point of 480 ° C and corresponds to he composition (mol.%): CaCl2 (45.8) – NaCl (47.0) – CaO (7.2).

Phase relations in the Tl2 Te–TlBiТe2 –TlTbTe2 system

The phase equilibria in the Tl2Te–TlBiТe2–TlTbTe2 concentration area of the Tl–Bi–Tb-Te quaternary system were investigated by using the differential thermal analysis and powder X-ray diffraction techniques. The diagram of the solid-phase equilibria of this system at room temperature was constructed. It was established that the Tl9BiTe6–Tl9TbTe6 section divides the Tl2Te–TlBiТe2–TlTbTe2 system into two independent subsystems. It was found that the Tl2Te–Tl9BiTe6–Tl9TbTe6 subsystem is characterized by the formation of a wide field of solid solutions with a Tl5Te3 structure (δ-phase) that occupy more than 90% of the area of the concentration triangle. The results of X-ray phase analysis of alloys of the Tl9BiTe6–Tl9TbTe6–TlTbTe2–TlBiТe2 subsystem showed the formation of wide regions of solid solutions based on TlTbTe2 and TlBiTe2 along the section of TlTbTe2–TlBiTe2 ((β1- and β2-phases) and made it possible to determine the location of the heterogeneous phase regions in this subsystem. The parameters of crystal lattices of mutually saturated compositions of the β1-, β2-, and δ-phases are calculated from powder diffraction patterns.The paper also presents some polythermal sections, isothermal sections at 740 and 780 K of the phase diagram, as well as projections of the liquidus and solidus surfaces of the Tl2Te–Tl9BiТe6–Tl9TbTe6 subsystem. The liquidus surface consists of three fields of the primary crystallization of α (Tl2Te)-, δ- and β1-phase. The constructed isothermal sections clearly demonstrate that the directions of the tie lines do not coincide with the T–x planes of the studied internal sections, which is characteristic of non-quasi-binary polythermal sections. The obtained new phases are of interest as potential thermoelectric and magnetic materials.

Optimization of the Composition and Structure of Deformable Heat Resistant Aluminum Alloy

The necessity of finding scientifically grounded methods for the development of new heat-resistant, wear-resistant and corrosion-resistant aluminum alloys is presented in the present work. For this purpose, the analysis of modern methods for computer calculation of phase diagrams in multicomponent metal systems using the Thermo-Calc program was carried out. Therefore, a quantitative analysis of the phase diagram the Al-Cu-Mn-Zr system was carried out, as the basis of deformable high-temperature aluminum alloys. Isothermal and polythermal sections of the phase diagram were calculated in this system. The temperatures of phase transformations were calculated. The mass and volume fractions of the phases in the studied alloys were calculated. The range of concentrations and temperatures at which the maximum amount of dispersoids Al20Cu2Mn3 may be achieved, was defined. The minimum amount of Al2Cu phase is calculated, which should correspond to the best heat resistance of alloys. It is substantiated that in the alloys of a new generation of ALTEK type, the use of homogenization and quenching operations is inexpedient, which implies the possibility of a significant reduction in the cost of heat treatment in comparison with industrial alloys, such as 1201.

Phase equilibria in the ternary reciprocal system Li, Ba // BO2, F and growth of bulk β-BaB2O4 crystals

In order to find the optimum solvent for the growth of nonlinear optical β-BaB2O4 crystals, the phase relationships in the ternary reciprocal system Li, Ba // BO2, F have been studied using solid state synthesis, differential thermal analysis and X-ray powder diffraction. Isothermal and polythermal sections of the system Li, Ba // BO2, F are reported. In the studied system, the following compounds are formed: LiBa2B5O10 (melts by peritectic reaction at 930°C, i.e. 1203 K) and LiBaF3 (melts incongruently at 850°C, i.e. 1123 K). Visual polythermal analysis of seeding and growth of β-BaB2O4 crystals in this system was carried out. The primary crystallization field of β-BaB2O4 was defined. Using the top-seeded pulling technique, a β-BaB2O4 crystal of 93 mm in diameter, 34 mm in height and 520 g in weight has been grown.

Effect of Al3Ni and Mg2Si Eutectic Phases on Casting Properties and Hardening of an Al-7% Zn-3% Mg Alloy

The formation of eutectics in Al–Zn–Mg–Ni and Al–Zn–Mg–Si systems is studied by means of metallography, DSC, EPMA, X-ray spectroscopy and thermodynamical calculations. Polythermal sections of the corresponding phase diagrams are constructed. The concentrations and temperatures of binary eutectic reactions L → (Al) + Al3Ni and L → (Al) + Mg2Si in quaternary alloys are determined. Nonequilibrium solidification in Al–7% Zn–3% Mg-based alloys ceases at approximately 480 °C. The alloys close by composition to binary eutectics have considerably improved casting properties as compared to the base Al–7% Zn–3% Mg composition. In particular, hot tearing susceptibility is much less in alloys with Al3Ni or Mg2Si. These results are corroborated by measurements of thermal contraction during solidification. The alloys containing binary eutectics exhibit much lower temperatures of contraction onset and less thermal strain is accumulated in the solidification range. Fine eutectic morphology enables fragmentation and spheroidization of intermetallic particles during annealing. The presence of Al3Ni and Mg2Si particles does not decrease the precipitation hardening effect associated with precipitation of the T′ (AlMgZn) phase. Improved casting properties and good mechanical properties of castings allow the application of Al–Zn–Mg alloys with binary eutectics formed by Al3Ni or Mg2Si as foundry alloys.