Ternary Eutectic Point Research Articles

Structural and thermodynamic aspects of niobium deposition in the system LiF-KF-K2NbF7

Abstract The complex physico-chemical analysis of the system LiF-KF-K2NbF7, based on the phase diagram, density, surface tension, and viscosity measurements, was performed. The results proved the presence of the congruently melting compound K3NbF8 even in the ternary melts. The calculated co-ordinates of the two ternary eutectic points are: e1: 22.3 mole % LiF, 9.4 mole % KF; 68.3 mole % K2NbF7; te = 649 °C; e2: 45.5 mole % LiF, 51.7 mole % KF; 2.8 mole % K2NbF7; te = 486 °C. The probable inaccuracy in the calculated ternary phase diagram is 4.7 °C. The degree of thermal dissociation of the additive compound K3NbF8 α0 = 0.55 at 1100 K, calculated from the density measurement agrees well with the value determined from the analysis of the phase diagram (α0 = 0.44) as well as from the viscosity measurement (α0 = 0.45 at 1100 K) and refers to the pronounced thermal dissociation of this compound at melting. The formation of K3NbF8 was confirmed by all of the followed physico-chemical parameters and it is the general feature of this system. The deposition of Nb from the LiF-KF-K2NbF7 melts takes place via the reversible, diffusion-controlled two-step reduction mechanism [ NbF 7 ] 2− + e − = [ NbF 6 ] 2− + F − [ NbF 6 ] 2− + 4e − = Nb (0) + 6 F − In the presence of oxygen in the melt the formation of the [NbOF5]2− or/and [NbO2F]− oxyfluorocomplexes takes place, depending on the concentration of O2− anions. Good experimental conditions for niobium deposition process can be expected when nO/nNb(V) 1 inhomogeneous niobium deposits containing niobium oxide solid solution, even a non-metal deposit could be obtained. The diffusion coefficients of electroactive species were calculated from the results of electrochemical measurements.

Phase equilibria in the Ti-rich corner of the Ti-Si-Ga system

Phase relations in the ternary Ti-Si-Ga system have been established experimentally by means of a study of alloy samples in the as-cast condition and annealed at 1350 °C. The alloys were prepared by arc melting. The investigation was carried out using physico chemical methods of analyses (metallography, X-ray powder diffraction, differential thermal analysis, and electron probe microanalysis over a limited composition range with samples containing less than 38 at.% Ga and more than 62 at.% Ti. Liquidus and solidus surface projections, the isothermal section at 1350 °C, and the isopleth at 68 at.% Ti are presented. Three surfaces of primary crystallization of phases have been established: extended ones for Ti5(Si,Ga)3 and β (Ti-base solid solution) and a narrow one of Ti2Ga. The monovariant curves separating these are due to the eutectic reactions L↔β+Ti5(Si,Ga)3 and L↔β+Ti2Ga and to the L+Ti5(Si,Ga)3↔Ti2Ga peritectic reaction. The three-phase region (β+Ti5(Si,Ga)3+Ti2Ga) results from the four-phase eutectic reaction L↔β+Ti5(Si,Ga)3+Ti2Ga. The composition of the ternary eutectic point E and the compositions of the coexisting solid phases have been determined. The solubilities of Si in the gallides, and of Ga in Ti5Si3 and of both the elements in Ti are given.

Phase diagram of the ternary system CeCl 3–KCl–LiCl

The phase diagram of the ternary system CeCl 3–KCl–LiCl has been investigated by means of differential thermal analysis (DTA). It was found that the ternary system can be subdivided into two pseudoternary systems and no ternary compound was found in the whole ternary system. It was determined that there are six surfaces corresponding to the primary crystallization of KCl, LiCl, CeCl 3, K 3Ce 5Cl 18, K 2CeCl 5 and K 3CeCl 6. There are two ternary eutectic points, E 1 (15.6 wt% KCl, 19.3 wt% LiCl, 65.1 wt% CeCl 3; 395°C) and E 2 (13.6 wt% CeCl 3, 50.8 wt% KCl, 35.6 wt% LiCl; 340°C), and one ternary peritectic point, P (68.1 wt% CeCl 3, 13.5 wt% KCl, 18.4 wt% LiCl; 398°C), in the system CeCl 3–KCl–LiCl.

Phase diagram of SmCl 3PbCl 2MgCl 2

The phase diagram of the rare-earth system SmCl 3PbCl 2MgCl 2 has been investigated by DTA. The results of the ternary system are as follows: four liquidus surfaces corresponding to the primary crystallization of SmCl 3, PbCl 2, MgCl 2 and PbSm 3Cl 11, respectively, five secondary crystallization lines, the ternary eutectic point E = 695 K (25.0 mol% SmCl 3, 57.0 mol% PbCl 2), and the ternary peritectic point P = 713 K (31.5 mol% SmCl 3, 48.0 mol% PbCl 2). The reactions between four equilibrium phases are: L P+SmCl 3⇌PbSm 3Cl 11+MgCl 2 L E⇌PbSm 3Cl 11+PbCl 2+MgCl 2

Phase diagram of the system KFKBF 4K 2TiF 6

The phase diagrams of the binary system KBF 4K 2TiF 6 and of the ternary system KFKBF 4K 2TiF 6 were determined using the thermal analysis method. The subsequent coupled analysis of the thermodynamic and phase diagram data was performed to obtain a thermodynamically consistent phase diagram. In the system KFKBF 4K 2TiF 6, the intermediate compound K 3TiF 7 is formed. The K 3TiF 7KBF 4 joint divides the ternary system into two simple eutectic ones. The calculated coordinates of the two ternary eutectic points are: e 1: 26 mol% KF, 69 mol% KBF 4, 5 mol% K 2TiF 6, t e1 = 448°C; and e 2: 4 mol% KF, 69 mol% KBF 4, 27 mol% K 2TiF 6, t e2 = 440°C. The system KBF 4K 2TiF 6 is a simple eutectic one with the calculated coordinates of the eutectic point being 28 mol% K 2TiF 6 and 448°C. The probable inaccuracy in the calculated ternary phase diagram is 11.5°C.

Equilibrium phase diagram of the water-sucrose-NaCl system

The solid-liquid equilibrium phase relationships in the ternary system water-NaCl-sucrose have been established with the aid of DSC measurements in the water-rich region and literature data. The phase coexistence conditions are represented in a plane projection of the three-dimensional phase diagram. The existence of the following stoichiometric hydrates has been taken into account: NaCl·2H 2O, C 12H 22O 11·2.5H 2O, C 12H 22O 11·3.5H 2O and NaCl·C 12H 22O 11·2H 2O. The coordinates of the binary and ternary eutectic and peritectic points are established with varying degrees of confidence.

Effects of Be and Fe additions on the microstructure and mechanical properties of A357.0 alloys

A357 hypoeutectic alloy is a heat-treatable Al-Si-Mg system with a nominal composition of Al-7 pct Si and about 0.6 pct Mg have widespreaded applications, especially in the aerospace and automotive industries. The purpose of this study was to determine the influences of Be and Fe content on the microstructure and mechanical properties of A357.0 alloys. Distinct morphologies were discerned between Be-containing and Be-free alloys. The Be-free alloys contain larger amount of iron-bearing phases with Mg than in Be-containing alloys. The addition of Be can change the plateletlike structure of iron-bearing phases to a comparatively harmless round nodular form. Also, the amounts of iron-rich phases are significantly lower and the silicon particles are smaller and more spherical in the Be-containing alloys. Small amounts of Be in A357.0 caused significant increases in the precipitation kinetics of Mg2Si. It was found that the addition of Be lowers the ternary and binary eutectic melting point. The amount of Mg available to form the major strengthening phase Mg2Si is increased promoting the tensile strength of A357.0 casting. The tensile properties were improved with decreasing Fe content and the addition of Be. The effect is more apparent in the higher Fe alloys than that in the lower Fe alloys.

Phase diagram of the ternary system SmCl 3NaClCaCl 2

The phase diagram of molten salts of the rare earth system SmCl 3NaClCaCl 2 has been investigated by DTA. For four liquidus corresponding to the primary crystallization of SmCl 3, NaCl, CaCl 2 and 2NaCl · SmCl 3, five univariant lines related to the secondary crystallization, ternary eutectic point E = 376°C (33.1 mol% SmCl 3, 46.9 mol% NaCl) and ternary peritectic point P = 389°C (29.3 mol% SmCl 3, 52.6 mol% NaCl) were found.

The reaction of nitrogen with dilute solutions of barium in liquid lithium: electrical resistivity, X-ray phase analysis, kinetic and thermal analysis studies

The reaction of nitrogen with liquid lithium containing dissolved barium which follows a solution–precipitation mechanism has been studied. Initially, nitrogen dissolves in the liquid metal to form an homogeneous solution; the reaction is first order with respect to nitrogen with an activation energy of 33.6 kJ mol–1. Subsequently, it reacts to form a precipitate of Li3N; the Li3N crystallisation face is dependent on the barium content of the solution, nitrogen solubility rising with increasing barium content. The ternary nitride, LiBaN, is only formed on cooling the solution; there is no evidence for Ba2N or Ba3N2 formation. This behaviour contrasts with that in the corresponding Na–M–N (M = Sr or Ba) systems where the solubility is directly proportional to the alkaline-earth metal content of the solution and the precipitating phase is the alkaline-earth metal subnitride. M2N (M = Sr or Ba). Analysis of the crystallisation fields of Li, Li4Ba, LiBaN and Li3N indicated they are separated by monovariant curves which fall from the binary eutectics (Li–Ba, xBa= 0.105 and 416 K; Li–N. degenerate at 453.5 K, Li3N–LiBaN, unknown) through a quasi-peritectic equilibrium involving liquid, lithium, Li4Ba and LiBaN (372 K) to a ternary eutectic point based on liquid, lithium. Li3N and LiBaN (368 K).

Experimental thermodynamics and phase equilibria estimation in Zr-fluoride glasses

Abstract The phase diagram calculation of the ternary system BaF2NaFZrF4 based on the Hoch-Arpshofen model is presented in this paper. The information needed for this calculation comprises the thermodynamic quantities relative to the three pure salts and to the three limiting binary mixtures. The calculated position of the ternary eutectic points is compared with the range composition glass.

Comparative study on the effect of iron and silicon addition on the microstructure and mechanical properties of aluminium-lithium powder atomized alloys

The present work was conducted on a wide series of Al-Si, Al-Li, Al-Li-Si and Al-Li-Fe alloys produced by centrifugal atomization. Solidification in Al-Si powders occurs by heterogeneous nucleation at the interface with the atmosphere, followed by propagation of the solidification front towards the particle centre. Addition of 3% Li to the Al-Si alloys shifts the ternary eutectic point to less than 4% Si. The eutectic structure is a mixture of aluminium and AlLiSi phases. For Al-2.5% Li-1.3% Fe, in addition to δ′-Al3Li phase precipitates, Al3Fe (needle-like) and Al6Fe (globular) phase precipitates are present. The volume fraction of Al3Fe dispersoids is not affected by the presence of the grain boundaries, and is enough to strengthen the precipitation-free zones.

Equilibrium phase diagram for the system PbO-CaO-CuO

In order to obtain essential information on the formation process of the high-Tc phase in the Bi, Pb-Sr-Ca-Cu-O system, phase equilibria in the system PbO-CaO-CuO have been studied, mainly by x-ray diffraction analysis and thermal analysis. Temperature versus composition diagrams were established for the systems PbO-CuO(Cu2O) and PbO(PbO2)–CaO in air. Three invariant points were detected in these systems: a eutectic reaction (PbO + Ca2PbO4 = L) at 847 ± 6°C, a peritectic reaction (Ca2PbO4 = L + CaO) at 980 ± 2°C, and a eutectic reaction (PbO + CuO = L) at 789 ± 3°C. For the system PbO(PbO2)-CaO-CuO, subsolidus phase equilibrium in air was established. The liquidus was also examined at 780, 800, and 820°C, and a ternary (PbO-Ca2PbO4-CuO) eutectic point was detected at 772 ± 6°C.

Crystallization processes in NiTiB glassy alloys of near-ternary-eutectic composition

The crystallization kinetics and mechanisms of three NiTiB glasses have been examined with a view to elucidating the roles of chemical composition and quenched structure on subsequent behaviour. Alloys of composition near a ternary-eutectic point have been chosen because they represent a real and complex situation where several crystalline phases may form simultaneously. Crystallization processes are analysed in terms of nucleation and growth stages. Different nucleation mechanisms have been observed for the different alloys: these seem to be best explained in terms of the detailed, short range ordered structure of the quenched glass. Analysis of crystal glass interface energies, based on structural examination using High Resolution Electron microscopy, indicates that it is not this energy term which controls the nucleation of crystals on annealing the glass. Crystal growth may involve a eutectic mechanism, or a single-phase mechanism controlled by interface or matrix-diffusion kinetics. Crystallization is fastest when eutectic nucleation and growth occurs: formation of the eutectic colony requires a specific sequence of phase nucleation, namely the initial formation of the phase of complex structure followed by the phase of simpler structure.

Influence of manganese on sintering processes in the Ti-Fe system 1. Volume changes in sintering of Ti-Fe-Mn compacts

An investigation was made of the influence of manganese on the sintering processes in the titanium-iron system in the area of temperatures of existence of the first ternary eutectic point. Powders of titanium obtained by hydride-calcium reduction, ferromanganese, and types PZh4M2 and V3 iron were used. A figure presents data on the character of the volume changes in sintering of compacts of mixtures of titanium and iron powders with and without manganese. The x-ray analysis was made on a DRON-0.5 instrument. The profiles of intensities of the x-ray lines of Ti(Fe, Mn) phase present in specimens of mixture II are shown. With an increase in sintering temperature the line, which is diffuse at 1050 degrees C, gradually narrows, and at 1250 degrees C a doublet appears. At the time, the lattice parameter changes from 0.2976 for unalloyed TiFe to 0.2991 nm for Ti(Fe, Mn) obtained at 1250 degrees C. To obtain Ti(Fe, Mn) compounds of the required composition, it is necessary to take into account the amount of evaporated manganese.

Ａｌ‐Ｓｉ‐Ｓｒ３元系状態図の研究

The aluminum corner of Al-Si-Sr ternary alloy system was investigated by means of inverse rate thermal analysis, identification by X-ray diffraction, EPMA analysis and microscopic observation.A ternary compound SrAl2Si2, named "T", exists in this ternary system and Al-T line is considered as a quasibinary system with a eutectic point at 1.1%Si, 2.4%Sr, 645°C. The aluminium corner is divided into two regions by the Al-T quasibinary system. A ternary eutectic point was determined to locate at 575°C, 13.1%Si, 0.03% Sr, which is very close to the Al-Si binary eutectic point. The modification effect of small amount of strontium addition on Al-Si alloys can be regarded to be due to the formation of fine ternary eutectic structure. In the Al-SrAl4-T region, a ternary eutectic point was found to locate at 643°C with 1.7%Si, 2.4%Sr.

Crystallization studies in the aluminum-rich corner of the aluminum-iron-manganese system

A method for determining the compositional areas of primary crystallization of Al-Fe-Mn alloys has been developed and used for the determination of the locations of the eutectic troughs, the ternary eutectic point, and the corresponding variation in composition of the FeAl3 and (FeMn)Al6 phases in the aluminum-rich corner of this system. The method uses slow crystallization in a relatively large and well stirred bath of alloy while periodically taking small samples of slurry at temperature by sucking these into silica tubes, followed by quenching and metallographic and electron probe examination. Growth of individual rounded aluminum and polygonal intermetallic crystals was observed during crystallization along the eutectic troughs.

Effect of nickel on sintering processes in the Ti-Fe system. Part I

Diffusional interaction in the Ti-Fe-Ni system is more vigorous than that in the Ti-Fe system. The temperature of the first ternary eutectic point in the Ti-Fe-Ni system, determined by the contact melting method, is 1040°C. During the sintering of compacts from a mixture of Ti, Fe, and Ni powders at temperatures above the eutectic point growth is observed, whose extent depends on the sintering temperature and the particle size of the powder employed: The smaller the particle size and the higher the sintering temperature, the smaller is the growth.

Search for the most stable PdSiCu metallic glass using the phase diagram approach

It is shown that slow cooling from the melt accompanied by intermittent annealing of alloys in the ternary system PdSiCu produces microstructures in which the “last freezing” areas of a ternary eutectic can be identified and subjected to electron microprobe analysis. In this way the composition of the ternary eutectic point was identified as Pd 80.1Si 14.7Cu 5.2. The combination of the slow cooling and microprobe techniques also permitted us to establish the most probable projection contours of the surfaces of primary crystallization in the eutectic region, as well as to identify the principal primary phases involved. The eutectic composition alloy is an easy glass former with a reduced glass temperature T rg of 0.63. This high value of T rg is the result of the lowest liquidus temperature T 1 of 698 °C attained at the eutectic point. The approach described in this paper is expected to be useful in locating regions of the probable glass-forming alloys in multicomponent systems.

The Quasi Ternary Eutectic System Polyethylene/Hexamethylbenzene/Adamantane

AbstractThis paper describes the crystallisation and melting behaviour of the quasi ternary system composed of heterodisperse polyethylene, and the diluents hexamethylbenzene and adamantane. The simplified theory of melting point depression according to Flory and Huggins predicts a ternary eutectic point for this system, which was verified experimentally by differential scanning calorimetry. Morphological investigations revealed a complex rod‐like eutectic microstructure with characteristic dimensions in the micron range1.

The cryoprotective properties of hydroxyethyl starch investigated by means of differential thermal analysis

Phase transition temperatures of the water-rich part of the H 2O-NaCl-HES ternary system have been studied by means of differential thermal analysis. The experimental data indicate that the protective action of the macromolecular agent HES is different from that of DMSO and glycerol which seems essentially to be due to colligative properties. As expected, there is no evidence of a significant freezing-point depression caused by HES concentrated up to 40 wt%. The occurrence of a ternary eutectic point may therefore be excluded. Instead, an isothermal eutectic trough is observed. The extrapolated course of its projection onto the basal composition triangle indicates that a certain portion of water is absorbed by HES and kept from freezing, i.e., appears to be thermally inert within the range of temperatures studied. The protective action of HES against solution effects, therefore, is attributed to its water-absorptive capacity and kinetics instead of a postponement of lethal salt enrichment to lower temperatures as caused by DMSO or glycerol. Consequently, it is possible to determine a minimum initial HES concentration that completely prevents lethal salt enrichment during cooling. For the case of red blood cells, the derived algebraic expression yields an initial HES fraction of 11 wt% if the respective values are inserted.