Polythermal Sections Research Articles

Solubility of Calcium and Zirconium Oxides in Melts CaO-(CaCl2-MCl)eut and CaO-CaCl2-MCl (M - Li, Na, K)

The behaviour of calcium oxide in eutectics of CaCl2–MCl and zirconium dioxide in polythermal sections of the ternary systems CaO–CaCl2–MCl (where M = Li, Na, K) has been investigation used methods of thermal and X-Ray analysis. It has been shown that equilibrium content of calcium oxide in the melt CaO–CaCl2–LiCl is much higher than similar melt composition CaO–CaCl2–MCl (M = Na, K). It has been established that the solubility of zirconium dioxide in the test melts rises with increasing acidity of the appropriate melt.

Verification of the T–x–y diagram of the Ag–Au–Bi system using a 3D computer model

Using two variants (with and without decomposition of the compound Au2Bi) of a 3D computer model of the T–x–y diagram of the system Ag–Au–Bi, it was shown that the published polythermal sections (both experimental and calculated by the CALPHAD method) agree in the high-temperature range of the T–x–y diagram for phase regions with melt, whereas in the low-temperature range the decomposition of a solid solution based on the compound Au2Bi is not taken into account.

Phase diagram of the Co–Al–W system. structure and phase transformations near the Co3(Al, W) intermetallic composition range

Low-temperature portion of the polythermal section for the Co–Al–W system in the vicinity of the Co3(Al, W) intermetallic composition has been studied experimentally using electron microscopy and hightemperature X-ray diffraction analysis. Low-temperature structural phase transformations and temperature ranges of the existence of phases have been determined. The morphology of Co3(Al, W) intermetallic particles was studied as a function of the tungsten content in alloys.

Effect of Mn, Al, Ni, and C Content on the Equilibrium Phase Composition of Alloys Based on the Fe–Mn–Al–Ni–C System

A Thermo-Calc program is used to calculate isothermal and polythermal sections of diagrams and phase composition for alloys of the Fe–Mn–Al, Fe–Mn–Al–Ni, and Fe–Mn–Al–Ni–C systems. Phase diagrams are used to study the effect of nickel, aluminum, manganese, and carbon on the equilibrium structure of alloys of the Fe–Mn–Al–Ni–C system. Concentration ranges are determined for existence of single-phase γ-alloys in the range 1000–1200°C. It is established that achievement of a considerable aluminum content (10%) and existence of increased specific strength for austenitic alloys of the Fe–Mn–Al–Ni–C system containing not less than 5% Ni is possible with a manganese content of not less than 20% and carbon not less than 1.4%.

3D model of the T–x–y diagram of the Bi–In–Sn system for designing microstructure of alloys

The published experimental and calculated data (binary systems, x–y projection of the liquidus, table of invariant reactions with the liquid phase, and one isothermal and two polythermal sections) were used for constructing a spatial computer model of the T–x–y diagram of the Bi–In–Sn system that was supplemented with the regions of the decomposition of the compound Bi m In n and the polymorphic transformation of tin. It was determined that the T–x–y diagram comprises 173 surfaces and 74 phase regions. Using the model for analyzing the material balances of phases and their microstructural components at all the stages of crystallization was demonstrated.

Phase diagrams with nonstoichiometric intermediate inclusion compounds

A model was presented for the p–T diagram of a binary system comprising a polymer and a highly volatile component in which there are intermediate nonstoichiometric phases. The most characteristic polythermal and polybaric sections of the spatial p–T–x diagram are considered.

Phase Composition of Light-Weight Steels and Alloys Based on the Fe–Mn–Al–C System

A Thermo-Calc program is used to calculate isothermal and polythermal sections of diagrams and phase composition for a series of alloys of the Fe–Mn–Al–Si–Mo–C–N system. Microstructure of these alloys is studied after quenching, hot and warm deformation, and ageing at 550°C. It is established that the phase equilibrium diagram of the Fe–Mn–Al–C system may be used for predicting alloy structure for this system after different forms of treatment. Alloys with a single-phase γ-region in the range 1000–1200°C and containing 20% or more Mn should contain more than 1.5% C with an Al content of 7.5% and more than 2% C with a 9% aluminum content.

Crystallization kinetics of Mg–Cu–Yb–Ca–Ag metallic glasses

The paper presents research into a Mg–Cu–Yb system based metallic glassy alloys. Metallic glasses were prepared using induction melting and further injection on a spinning copper wheel. The effect of alloying by Ag and Ca on the glass forming ability and the kinetics of crystallization of Mg–Cu–Yb system based alloys were studied. The differential scanning calorimeter and X-ray diffractometer were used to investigate the kinetics of crystallization and the phase composition of the samples. An indicator of glass forming ability, effective activation energy of crystallization, and enthalpy of mixing were calculated. An increase of the Ca and Ag content has a positive effect on the glass forming ability, the effective activation energy of crystallization, and the enthalpy of mixing. The highest indicators of the glass forming ability and the thermal stability were found for alloys that contain both alloying elements. The Ag addition suppresses precipitation of the Mg2Cu phase during crystallization. A dual-phase glassy-nanocrystalline Mg structure was obtained in Mg65Cu25Yb10 and Mg59.5Cu22.9Yb11Ag6.6 alloys after annealing. Bulk samples with a composite glassy-crystalline structure were obtained in Mg59.5Cu22.9Yb11Ag6.6 and Mg64Cu21Yb9.5Ag5.5 alloys. A thermodynamic database for the Mg–Cu–Yb–Ca–Ag system was created to compare the process of crystallization of alloys with polythermal sections of the Mg–Cu–Yb–Ca–Ag phase diagram.

Three-dimensional model of phase diagram of Au-Bi-Sb system for clarification of thermodynamic calculations

A three-dimensional (3D) computer model of a T–x–y-diagram for an Au-Bi-Sb system is developed. It is established that it consists of 60 surfaces and 24 phase areas. It is used to show that works devoted to experimental studies and thermodynamic calculations of this system miss two surfaces and two phase areas in the iso- and polythermic sections.

ChemInform Abstract: Phase Equilibria in the Tl—TlI—Se System and Thermodynamic Properties of the Ternary Phases.

AbstractSeveral polythermal sections, the isothermal section at 300 K, and the projection of the liquidus surface of the Tl‐TlI‐Se system are constructed using DTA, XRD, and EMF methods.

Model state diagram for a ternary reciprocal system with a ternary nonstoichiometric incongruent phase

A model melting diagram for a ternary reciprocal system with solid solutions of initial components and a ternary nonstoichiometric intermediate incongruent phase is considered. Some isothermal sections from certain interinvariant regions and the most characteristic polythermal sections are given.

Phase equilibria in the Tl–TlI–Se system and thermodynamic properties of the ternary phases

By using differential thermal analysis (DTA), X-ray analysis and electromotive force (EMF) methods the Tl–Se–I system was investigated in the Tl–TlI–Se composition range. Several polythermal sections, the isothermal section at 300K and the projection of the liquidus surface of the system were constructed. The fields of primary crystallization of phases as well as types and coordinates of non- and monovariant equilibria were determined. Formation of two congruently melting ternary compounds (Tl5Se2I at 720K, and Tl6SeI4 at 705K) was observed. The system is characterized by the existence of wide areas of solid solutions on the base of Tl2Se (α-phase) and Tl5Se2I (δ-phase). The partial molar thermodynamic functions (ΔG‾,ΔH‾,ΔS‾) of thallium as well as the standard integral thermodynamic functions of Tl6SeI4 and Tl5Se2I compounds and Tl5Se3−xIx solid solution (for x=0.2, 0.4, 0.5, and 0.8) were calculated based on the EMF data.

Phase equilibria in the quasiternary system Ag2S–Ga2S3–In2S3 and optical properties of (Ga55In45)2S300, (Ga54.59In44.66Er0.75)2S300 single crystals

The quasiternary system Ag2S–Ga2S3–In2S3 was investigated by differential thermal, X-ray diffraction analyses. The phase diagram of the Ga2S3–In2S3 system and nine polythermal sections, isothermal section at 820K and the liquidus surface projection were constructed. The existence of the large solid solutions ranges of binary and ternary compounds was established. The range of the existence of the quaternary phase AgGaxIn5−xS8 (2.25≤x≤2.85) at 820K was determined. The single crystals (Ga55In45)2S300 and (Ga54.59In44.66Er0.75)2S300 were grown by a directional crystallization method from solution-melt. Optical absorption spectra in the 500–1600nm range were recorded. The luminescence of the (Ga54.59In44.66Er0.75)2S300 single crystal shows a maximum at 1530nm for the excitation wavelengths of 532 and 980nm at 80 and 300K.

THE EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE AND PHASE COMPOSITION OF TI–AL–NB–MO-SYSTEM BASED TNM-TYPE Β-SOLIDIFIED CASTINGS

The work purpose is a study of the effect of hot isostatic pressing (HIP) on the microstructure and phase composition of titanium aluminide based alloys using experimental and computational methods. Isothermal and polythermal sections of the Ti–Al–Nb–Mo system, liquidus, solidus, and other phase change temperatures are calculated by dint of Thermo-Calc program. General character of microstructure after vacuum annealing and HIP-processing at t = 1250 °C is shown to be about identical: γ + α2 eutectoid colonies and relatively compact particles of β and γ phases. However vacuum annealing, unlike HIP, does not result in elimination of casting porosity. The data of metallographic and X-ray microspectroscopic analyses confirm the computational results as a whole.

Calculation of phase equilibria between the gas and the solid phases in the Nb-I and He-Nb-I systems

Phase equilibria in the Nb-I and He-Nb-I systems were calculated. A P-T projection and isobaric sections of the phase diagram of the Nb-I system at 0.1 and 1 atm were constructed. Polythermal sections in the He-Nb-I system are topologically equivalent to the phase diagram of the Nb-I system but have some geometric features. The nature of such features was determined.

Defining Borders of Vitrification Region in the Li2O⋅B2O3-B2O3-Yb2O3⋅B2O3 System

ABSTRACTPhase relations along the Li2O⋅2B2O3-Yb2O3⋅B2O3 polythermal section of the Li2O –B2O3–Yb2O3 system were investigated by differential thermal analysis, x-ray diffraction, and microstructural analysis. The state phase diagram of the Li2O⋅2B2O3-Yb2O3⋅B2O3 section is an eutectic system with invariant eutectic point corresponding to ∼0.2 mole fraction of Yb2O3⋅B2O3 and 800 °C. According to physico-chemical analysis, the Li2O⋅2B2O3-Yb2O3⋅B2O3 polythermal section is quasi-binary, allowing us to partially triangulate the Li2O-B2O3-Yb2O3 system. The borders of the glass formation region were defined in the Li2O⋅2B2O3-B2O3-Yb2O3⋅B2O3 concentration triangle. The vitreous samples showed a semiconducting nature.

TernAPI program for the calculation of ternary phase diagrams with isolated miscibility gaps by the convex hull method

The first public version of TernAPI (ternary diagrams assessment programming interface) software package for ternary phase diagrams calculation by the convex hull method has been developed. Its reliability and efficiency have been proved on a large set of systems of different kind: organic liquids and fluids mixtures, water solutions, salts, oxides, metallic alloys. A remarkable advantage of TernAPI is a stable work in the case of isolated miscibility gaps (“islands”) described by a uniform Gibbs energy surface equation. It also contains several improvements of phase diagram calculation algorithm, a new module for x–T diagrams polythermal sections calculation and possibility of optimization of thermodynamic models parameters. NRTL model parameters for the acetic acid–N,N-dimethylformamide–cyclohexene ternary system have been optimized in this work. The specialized language based on Ruby and YAML is used for the description of thermodynamic models of phases.

Polythermal section Ge-SnAs of the Sn-As-Ge system

The T-x diagram of the polythermal section Ge-SnAs of the Sn-As-Ge system was constructed using the results of X-ray powder diffraction and differential thermal analyses. It was found that the Ge-SnAs section is not quasi-binary. In the ternary system, two four-phase peritectic transformations occur: L + GeAs ↔ Sn4As3 + Ge at 821 K and SnAs ↔ Sn4As3 + GeAs at 834 K.

Modeling the state diagrams of ternary reciprocal systems

A model p-T diagram of a eutectic-type ternary reciprocal system is presented. An isobaric cross section in the form of a projection onto a concentration diagram is shown. Isothermic and polythermic cross sections of a eutectic-type ternary reciprocal fusibility diagram with swept faces of a tetrahedral prism are created. A projection of the diagram of a ternary reciprocal system with solid solutions based on initial components with a ternary nonstoichiometric intermediate phase is considered.

Conditions of formation of “thick” plastic amorphous Fe-Co microwires in Fe75Si10B15-Co75Si10B15 system

Equilibrium and rapidly quenched Fe-Co-Si-B alloys are studied in Fe75Si10B15-Co75Si10B15 cross section. The polythermal cross section is developed in the range of melting and crystallization temperatures. Amorphous ribbons of alloys are produced by melt spinning, and rapidly quenched microwires in a glass sleeve with diameter of the metal core dcore = 10–100 μm are obtained by the Ulitovskii-Taylor technique. The structure and physical and mechanical properties of the alloys are studied. The concentration range of stability of “thick” amorphous plastic microwires with core diameter dcore ≥ 50 μm is determined using analysis of the phase diagram and content-property diagram. A special two-stage crystallization mechanism responsible for high glass-forming ability of microwires is established.