Low-melting Eutectics Research Articles

Effect of B2O3 on the viscosity, structure and crystalline phase of CaO–MgO–Al2O3–SiO2–MnO-based high alumina slags

The effects of B2O3 on viscosities, structures and phase transitions of CaO–MgO–Al2O3–SiO2–MnO-(0-8.0 wt%)B2O3 slags were investigated in this work. From the viscosity experimental results, the slag viscosities declined and the Eη decreased from 205.19 to 175.95 kJ/mol with the addition of B2O3 in slags from 0 to 8.0 wt%. From the structure analysis by using FTIR and XPS, B2O3 entered into the silicate network to increase the slag polymerization degree, while the formation of simple two-dimensional BO3 trihedral units could significantly decline the symmetry and stability of the structure. The effects of decreasing the network stability and forming low-melting eutectics were more dominated than the effects of increasing the structure polymerization degree, which could reduce the slag viscosity. Furthermore, adding B2O3 could decrease the slag initial precipitation temperature and change the primary crystal phase of the slag from melilite to spinel. The comprehensive effects of reducing the slag structure stability and decreasing the influence of solid phase on viscosity eventually resulted in the improvement of the slag fluidity.

Evaluation on thermal pyrolysis of biomass straw waste: Focusing aspects of products yields, syngas emissions and solid products characterization

AbstractIn this study, a systematic and quantitative investigation of the pyrolysis characteristics of biomass was conducted in a fixed‐bed tubular reactor, and the influence of pyrolysis temperature on product yields, gas emission characteristics, and syngas compositions as well as physicochemical characterization of resulting solids (i.e., char/ash morphologies, mineral transformations, and elemental compositions) was explored in detail. The pyrolysis experiments were performed under N2, and the resulting solid characterization was detected by XRD, SEM, and EDX. The results indicated that with increasing the pyrolysis temperature from 400 to 800°C, the gaseous product yields increased from 54.9% to 66.7%, while the solid product yield showed a reverse trend, varying within 27.7%–40.5%. Meanwhile, the volume fraction of H2 in syngas increased from 7% to 33%, while the CO2 presented an opposite trend, suggesting that high temperature favored H2 formation and inhibited CO2 formation. On the whole, the CO and CO2 emissions were prior to CH4, H2, and CnHm in sequence. A large amount of sylvite (KCl), quartz (SiO2), dolomite (CaMg(CO3)2), and pyroxene (CaMgSi2O6) in the resulting solids were identified in crystal phases. Higher pyrolysis temperature had a significant influence on solid microstructures, resulting in a relatively higher slagging tendency due to low melting eutectics containing K‐rich and Ca‐rich minerals.

Understanding impacts of introducing CO2 in N2 and operation conditions on physicochemical property and fusion behaviour of solid products during thermal decomposition of corn stalks

The total annual production of corn stalk (CS), a byproduct of corn processing, in China was as high as 3.1 × 108 tons, the utilization of which had great potential. The objective of this study was to investigate the characterization of the resulting solids during thermal conversion of CS under different atmospheres and to deepen the understanding of the effects of introducing CO2 in N2. The impacts of temperature, atmosphere, and particle residence time on the solid yield, ash characteristics were elucidated. It was found that the solid yields decreased with increasing temperature. For a given temperature below 600 °C, the solid yields in 20% CO2/80% N2 were higher than those in N2. But when the temperature was above 600 °C, the opposite trend was observed. Increasing residence time substantially improved carbon conversion. Compared with the solids formed below 600 °C, the 800 °C solids contained more agglomerates, which were composed of K-bearing and Ca-bearing minerals. The ash fusion temperature (AFT) increased with rising pyrolysis/gasification temperature. After substituting N2 with CO2 in the pyrolysis agent, the AFT became higher. Under the current conditions, ash deposition could occur even if the operating temperature was lower than the softening temperature (ST) due to the formation of low melting eutectics.

Microstructure, chemical composition, and dielectric response of CaCu3Ti4O12 ceramics doped with F, Al, and Mg ions

Ceramics with nominal chemical composition CaCu3Ti4O12 (CCTO), CaCu3Ti3.96Al0.04O11.96F0.04 (CCTOAF), and Ca0.98Mg0.08Cu2.94Ti3.96Al0.04O11.96F0.04 (CCTOMAF) were prepared by the solid-state reactions technique. Using SEM, EDX, XPS, EPR, NMR, and complex impedance spectroscopy, the microstructure, elements distribution, chemical composition of grains and grain boundaries, and the dielectric response of ceramics were investigated. In the ССТО, CCTOAF, and CCTOMAF series, the average grain size increases, the degree of copper segregation at the grain boundaries is inversely related to grain size, and the dielectric loss decreases from 0.071 to 0.047 and 0.030, respectively, while dielectric permittivity ε′ at 1 kHz is 5.6 × 104, 7.1 × 104, and 4.3 × 104, respectively. Additives of Al, Mg, F and milled particles (ZrO2, Al2O3, and SiO2) can either partially introduce into the perovskite structure or form low-melting eutectics at the grain boundaries, causing abnormal grain growth. The presence of copper ions in various oxidation states, as well as evidence of exchange spin interactions between them, was confirmed in all samples.

Amorphization of Ethenzamide and Ethenzamide Cocrystals-A Case Study of Single and Binary Systems Forming Low-Melting Eutectic Phases Loaded on/in Silica Gel.

The applicability of different solvent-free approaches leading to the amorphization of active pharmaceutical ingredients (APIs) was tested. Ethenzamide (ET), an analgesic and anti-inflammatory drug, and two ethenzamide cocrystals with glutaric acid (GLU) and ethyl malonic acid (EMA) as coformers were used as pharmaceutical models. Calcinated and thermally untreated silica gel was applied as an amorphous reagent. Three methods were used to prepare the samples: manual physical mixing, melting, and grinding in a ball mill. The ET:GLU and ET:EMA cocrystals forming low-melting eutectic phases were selected as the best candidates for testing amorphization by thermal treatment. The progress and degree of amorphousness were determined using instrumental techniques: solid-state NMR spectroscopy, powder X-ray diffraction, and differential scanning calorimetry. In each case, the API amorphization was complete and the process was irreversible. A comparative analysis of the dissolution profiles showed that the dissolution kinetics for each sample are significantly different. The nature and mechanism of this distinction are discussed.

The effect of TIG welding on the structure and hardness of butt joints made of Inconel 718

The tests discussed in the article aimed to analyse the structure and hardness of the heat affected zone and that of the weld in thin butt joints (1.0 mm) made of Inconel 718 using the TIG method and variable welding linear energy restricted within the range of 45 J/mm to 80 J/mm. The test joints were subjected to visual tests, macro and microscopic metallographic tests, scanning electron microscopy-based structural observations and hardness measurements. The tests concerned with the effect of the TIG welding of butt joints made of 1.0 mm thick sheets (Inconel 718) in laboratory conditions revealed that the most favourable quality of the sheets was obtained when welding arc linear energy was restricted within the range of approximately 45 J/mm to 80 J/mm. An increase in linear energy within the above-presented range led to an increase in the width of the weld and that of the HAZ (observed in the joints subjected to macroscopic metallographic tests). In addition, an increase in linear energy restricted within the aforesaid range increased the grain size in matrix γ (in the HAZ) from approximately 10 μm–20 μm. The structure of the weld contained the zone of columnar grains oriented towards the fusion line as well as large groups of primary grains having the dendritic structure with clearly visible axes of primary dendrites of varied orientation. In addition, the weld structure also contained precipitates in the form of low-melting eutectics located in interdendritic spaces.

Viscosity, crystallization temperature, phase composition, and structure of the low-basicity СаО–SiO2–B2O3–Cr2O3–Аl2O3–МgO slag system

The influence of B2O3 on viscosity, crystallization temperature, phase composition, and structure of fluorine-free slags of the СаО–SiO2–B2O3–2 % Cr2O3–3 % Аl2O3–8 % МgO system in the range of boron oxide content from 0 to 6% and basicity (B = CaO/SiO2 ) equal to 1.0 is studied by vibrational viscometry, phase composition thermodynamic modeling in combination with raman spectroscopy. It is found that boron oxide-free slag has the simplest structure, as indicated by the average amount of bridging oxygen BO equal to 0.73, and has a higher viscosity compared to boron-containing slags of 0.85‒0.60 Pa•s in the temperature range of 1400‒1450°C, and crystallization temperature of 1402°C. This is due to the high proportion of high-temperature compounds in the formed slag. The introduction of 2 to 6% boron oxide complicates the structure of the slag, which is accompanied by an increase in the average amount of bridging oxygen BO to 0.98 and 1.28, respectively. The resulting four-coordination structural elements [BO4], [CrO4] and [AlO4] are embedded in the silicon-oxygen lattice of the slag and complicate it, which increases the degree of polymerization. However, the formation of low-melting eutectics CaO•B2O3 and 2CaO•B2O3 after introduction of 2 and 6% boron oxide, despite the complexity of the structure of the formed slags, leads to a decrease in crystallization temperature to 1346 and 1265°C, an increase in the degree of slag superheating and a decrease in its viscosity to 0.9 and 0.55 Pa•s already at 1350°C. Thus, the addition of boron oxide to slag, despite the structure complication of the formed oxide system, leads to an increase in the liquid mobility of the slag due to the formation of a high proportion of low-temperature phases and a decrease in the proportion of medium- and high-temperature phases and a lower binding energy of boron with oxygen compared to silicon

Improving sintering kinetics and compositional homogeneity of Inconel 625 superalloy open-cell foams made by suspension impregnation method

Open-cell Inconel 625 superalloy foams were prepared by suspension impregnation method which involves replication of pure nickel foam ligaments with a mixed powder suspension and subsequent heat treatments. The objective of the present study is to find a suitable method ensuring complete densification of the superalloy foam ligaments without using low-melting additives and achieving uniform chemical composition at moderate sintering temperatures. Foams prepared using the above methodology were evaluated for the microstructure and compositional variation across the foam ligaments by scanning electron microscopy (SEM) coupled with electron dispersive spectroscopy (EDS). Quasi-static compressive properties of the foams were evaluated. It is shown that if elemental powders of Cr, Mo and Ni are used as additives to the superalloy powder suspension, high ligament density with uniform chemical composition conforming to the Inconel 625 specification is achieved at moderate sintering temperatures. These results are attributed to the formation of low melting eutectics and to acceleration of the diffusion kinetics due to the non-equilibrium thermodynamic conditions created by large compositional gradients in the presence of elemental powders.

Features of the Structure and Electrophysical Properties of Solid Solutions of the System (1-x-y) NaNbO3-xKNbO3-yCd0.5NbO3.

Ferroelectric ceramic materials based on the (1-x-y) NaNbO3-xKNbO3-yCd0.5NbO3 system (x = 0.05–0.65, y = 0.025–0.30, Δx = 0.05) were obtained by a two-stage solid-phase synthesis followed by sintering using conventional ceramic technology. It was found that the region of pure solid solutions extends to x = 0.70 at y = 0.05 and, with increasing y, it narrows down to x ≤ 0.10 at y = 0.25. Going out beyond the specified concentrations leads to the formation of a heterogeneous region. It is shown that the grain landscape of all studied ceramics is formed during recrystallization sintering in the presence of a liquid phase, the source of which is unreacted components (Na2CO3 with Tmelt. = 1126 K, K2CO3 with Tmelt. = 1164 K, KOH with Tmelt. = 677 K) and low-melting eutectics in niobate mixtures (NaNbO3, Tmelt. = 1260 K, KNbO3, Tmelt. = 1118 K). A study of the electrophysical properties at room temperature showed the nonmonotonic behavior of all dependences with extrema near symmetry transitions, which corresponds to the logic of changes in the electrophysical parameters in systems with morphotropic phase boundaries. An analysis of the evolution of dielectric spectra made it possible to distinguish three groups of solid solutions: classical ferroelectrics (y = 0.05–0.10), ferroelectrics with a diffuse phase transition (y = 0.30), and ferroelectrics relaxors (y = 0.15–0.25). A conclusion about the expediency of using the obtained data in the development of materials and devices based on such materials has been made.

Effect of different carbon sources on vacuum carbothermal reduction of low-grade phosphorus ore

In this study, the effect of different carbon sources on the carbothermal reduction of low-grade phosphate ore were examined using FactSage 7.2 calculations and vacuum reduction experiments. The thermodynamic calculations showed that the trend of the effect for three types of reducing agents was generally consistent under 1 Pa pressure and 14% carbon dosage. The reduction effect was maximum when graphite was used as the reducing agent, and a maximum mass of P was obtained at 1250?C. The vacuum experiment results showed that the reduction and volatilization ratios of phosphate rock increased with temperature for different carbon sources. Maximum reduction ratio was obtained using graphite in the temperature range 1250-1300?C. The reduction effect of pulverized coal was optimal at 1350?C, when SiO2, Al2O3 and MgO in the pulverized coal ash were exposed to form low-melting eutectics with CaO due to the increased degree of reaction, and the heat and mass transfer rates were increased. At this time, a maximum reduction ratio of 51.77% of the sample and a maximum volatilization ratio of 82.44% of P were achieved. Considering the cost-effectiveness, pulverized coal was the optimum carbon source for the treatment of low-grade phosphate rock using vacuum carbothermal reduction.

MODIFICATION OF THE CAST STRUCTURE OF AN EN AW 2011 ALLOY WITH HOMOGENIZATION

Aluminium alloys of group 2xxx contain copper as the main alloying element. Copper increases the strength and workability of the alloy, but also reduces the corrosion resistance and weldability. During casting, a nonequilibrium solidification occurs. Therefore, the cast alloy needs to be heat treated with a so-called homogenization process. Homogenization allows us to eliminate crystalline segregations and low-melting eutectics, and also causes changes in the morphology of intermetallic phases. The forming ability is in this way increased. In this research the subject of the investigations was the aluminium alloy with designation EN AW 2011 (AlCuBiPb), whereas the comparative analysis before and after homogenization annealing was made. Homogenization was conducted at 520 °C for 6 h. First, slices from two rods before and after homogenization were cut out, where three samples from each slice of the rod, namely in the middle, on D/4 and at the edge of the slice were prepared. Differential scanning calorimetry (DSC) was performed on all six samples, the results were compared with each other in order to establish the structure homogeneity before and after the homogenization process through the cross-section of the rod. Samples for light (LM) and scanning electron microscopy (SEM) were also prepared, whereas the phase composition and chemical homogeneity were analysed. Using the Thermo-Calc program, the nonequilibrium solidification was simulated and the phase formation during solidification was examined. From the obtained results, it was concluded that the homogenization was carried out successfully, due to a homogeneous chemical distribution in the examined phases and to a fairly homogeneous chemical composition throughout the cross-section of the rod slice.

Liquation cracking in Inconel 617 alloy by Laser and Laser-Arc Hybrid welding

ABSTRACT The present study investigates susceptibility of Inconel 617 to liquation cracking in laser-based welding techniques such as autogenous laser welding (ALW) and laser-MIG hybrid welding (LHW) with variation in heat input. Advanced characterization techniques such as high-speed Nano-Indentation testing and micro X-ray diffraction techniques were utilized to analyze microstructural variations in correlating mechanical behavior of low-melting eutectics formed in partially melted zone (PMZ). Results indicated that the liquation cracking in PMZ was associated with the constitutional liquation reaction between intermetallic carbides and austenite matrix. With increase in heat input, its susceptibility reduced, although with enhancement in grain-boundary liquid film formation and was associated with the constitutional liquation of (Cr, Mo)-rich M23C6 carbides and γ matrix. Combined effect of induced thermal stress with presence of low-melting eutectics in partially melted zone was found to greatly influence liquation-cracking susceptibility in both the welding processes. Indeed, ternary eutectic comprising metallic carbides of Cr and Mo and austenite-matrix with low nano-hardness values compared to that of hard carbides present in base metal and weld fusion zone re-confirmed their influence on cracking susceptibility. Increase in heat input enhanced dissolution of Mo-rich M6C carbides that attributed to stress-relaxation and thereby reduce cracking propensity.

A Study into the Influence of Different Factors on the Behavior of Alkaline Element Concentrations that Cause Bed Agglomeration

In recent years, studies into the processes of bed agglomeration during the combustion of biomass have become increasingly relevant. The agglomeration processes are most largely influenced by the alkaline components of ash, which form low-melting eutectics by reacting with silicates. Therefore, it is very important to determine the critical concentration, primarily, of potassium that forms the most low-melting eutectics in the bed, at which the particles begin to sinter. The experimental studies are aimed at to investigate the effect of the temperature and the concentrations of alkaline elements on the process of particle agglomeration during the combustion of various types of biomass as well as biomass and coal, studying the presence of bed drain, determining the critical concentration of potassium in the bed, and calculating the estimated time before the start of sintering under conditions of an increase of potassium concentration in the bed. The experimental techniques and characteristics of the four studied types of biomass are described. Data on the fraction of agglomerated particles in the bed at different temperatures and concentrations of alkaline elements are given. Upon replacing a part of the sand by iron oxides, agglomeration is observed only at high temperatures (850°C and more). The obtained data are compared with the results of similar experiments carried out under conditions of the fluidized bed; in these experiments, the effects of the fluidization rate, particle size, and excess air on the agglomeration processes are considered. It is noted that the limiting potassium concentration is lowest in the case of a fixed bed. It is shown that real objects should be used when studying the dependence of the behavior of the potassium concentration in the bed on the operation time. The choice of the fraction of bed drain with the addition of a screened material or fresh sand is of practical interest. The calculation techniques and calculated data obtained with use of them on the behavior of the potassium concentration in the bed under various conditions are presented. The fractions of bed drain during combustion of sunflower husks and bark and wood waste are determined. In addition, it is shown that the joint combustion of husks and coal sharply reduces the probability of bed agglomeration.

Effect of different carbon sources on vacuum carbothermal reduction of low-grade phosphorus ore

In this study, the effect of different carbon sources on the carbothermal reduction of low-grade phosphate ore were examined using FactSage7.2 calculations and vacuum reduction experiments. The thermodynamic calculations showed that the trend of the effect for three types of reducing agents was generally consistent under 1 Pa pressure and 14% carbon dosage. The reduction effect was maximum when graphite was used as the reducing agent, and a maximum mass of P was obtained at 1250 ?C. The vacuum experiment results showed that the reduction and volatilization ratios of phosphate rock increased with temperature for different carbon sources. Maximum reduction ratio was obtained using graphite in the temperature range 1250-1300 ?C. The reduction effect of pulverized coal was optimal at 1350 ?C, when SiO2, Al2O3, and MgO in the pulverized coal ash were exposed to form low-melting eutectics with CaO due to the increased degree of reaction, and the heat and mass transfer rates were increased. At this time, a maximum reduction ratio of 51.77% of the sample and a maximum volatilization ratio of 82.44% of P were achieved. Considering the cost effectiveness, pulverized coal was the optimum carbon source for the treatment of low-grade phosphate rock using vacuum carbothermal reduction.

Temperature and deformation conditions of gas bubbles welding at hot rolling

At production of hot-rolled product from middle-carbon and low-carbon steel, a surface defect “rolled-out bubble” is formed sometimes. To decrease rejections by surface defects like this one, it is necessary to know the mechanism of their origination. The comprehensive study by methods of micro-X-ray-spectral and X-ray-phase analysis on internal surface of the rolled-out bubbles and areas, located in the direct vicinity of the defects mentioned, allowed to determine the content of isolations, localized at the internal surface of the defects. The content was as follows (%, mas.): quartz - 24, tridymite - 28, magnetite - 48. By the method of differential scanning calorimetry the melting temperature of isolations on the internal surface of the rolled-out bubbles determined, amounted to 1178 dC, which corresponds to melting temperature of iron-silicon eutectic Fe 3 O 4 -SiO 2 . A mechanism of the defect “rolled-out bubble” formation proposed. According to the mechanism proposed, the inclusions of silicates, localized at the internal surface of the bubbles and complex inclusions based on silicon and iron oxides, form the low-melting eutectic of Fe 3 O 4 -SiO 2 type when interacting with oxygen of air during the heating before rolling. As a result of expanding forces during the rolling, in the surface metal layer, which has a liquid eutectic at the rolling temperatures, discontinuity flaws are formed. To avoid the defects it was proposed to keep the reheating and rolling temperature lower the melting temperature of the eutectic of Fe 3 O 4 -SiO 2 type. The corrected rolling regime allowed to exclude practically completely the rejections by defect “rolled-out bubble” and to decrease the metal consumption coefficient at production of rolled products from S355J2G3 and C45R steels.

Wet chemically derived Li4SiO4 nanowires as efficient CO2 sorbents at intermediate temperatures

Lithium silicate based ceramic sorbents are potential materials for CO2 sorption in the temperature range of 500–700 °C. However, its sorption performance at temperatures <500 °C is kinetically limited due to the formation of lithium carbonate as a hard surface layer that limits the CO2 diffusion to the reaction interface. This shortcoming in temperature of application has widely impeded its practical application in industrially important reaction environments such as in petrochemical processes. In the present study, we report compositionally tuned lithium silicate nanowires wherein the formation of hard lithium carbonate layer during the sorption process is addressed through the incorporation of low melting eutectics that softens the carbonate layer and facilitates an easier pathway for the diffusion of CO2. This modification is demonstrated to overcome the kinetic limitations of CO2 sorption in lithium silicate at lower temperatures (<500 °C). The nanowire morphology of lithium silicate also facilitated enhanced CO2 capture as the diffusion path-ways for lithium are considerably shorter compared to the conventional micron sized agglomerates. Further, the compositional tuning of lithium silicate nanowires helped to realize an absorption capacity value of 300 mgg−1 at 450 °C, a value seldom achieved for lithium silicate based materials at such low temperatures. The sorption capacity could also be fully regenerated at the same temperature by a pressure swing operation. The results thus pave the possibility of using modified lithium silicate compositions as CO2 sorbents in industrially significant chemical reaction processes such as high temperature water gas shift reaction where the temperatures are generally in the range of 350–450 °C.

Mechanism of deep eutectic solvents enhancing catalytic function of cytochrome P450 enzymes in biosynthesis and organic synthesis

Indigo is an insoluble blue dye, which generates serious pollution in its production process. Increasing focus has come to the biosynthesis of indigo that are more environment-preserved and high-efficient. Hence, this study was designed to explore the specific role of various deep eutectic solvents (DESs) on cytochromeP45-BM-3 catalyzing indole to produce indigo. DESs were synthesized by heating and stirring. The structure of the solvent was analyzed by nuclear magnetic resonance (NMR) and fourier transform infrared spectrum (FT-IR), and the relationship between the viscosity, density and refractive index of the solvent, and the water content of the solvent was examined. Circular dichroism spectrometer was used to detect the tertiary structure of the enzyme protein. The effect of solvent type, concentration, pH, temperature, and water content on the catalytic activity and stability of P450 BM-3 was measured using an ultraviolet spectrophotometer. A new solvent biphasic system was established using DESs and buffers, and indigo was prepared using recombinant E. coli-biocatalyzed indole. DESs were low-melting eutectics formed by molecules interaction of components through hydrogen bonding. The physical properties of DESs such as density, viscosity, and refractive index varied with water content and temperature of the solvent. The pH, water content, and temperature of DESs were positively correlated with the catalytic activity of P450 BM-3. To sum up, DESs can improve the catalytic activity and thermal stability of P450 BM-3. Indigo can be efficiently prepared using the DESs-buffer biphasic system.

Analysis of Chemical Composition Homogeneity in the Cross-section of the Rods Produced from Alloys of 6xxx Group

Abstract The alloys from Al–Mg–Si system provide an excellent combination of mechanical properties, heat treatment at extrusion temperature, good weldability, good corrosion resistance and formability. Owing to the high casting speed of rods or slabs, the solidification is rather non-equilibrium, resulting in defects in the material, such as crystalline segregations, the formation of low-melting eutectics, the unfavourable shape of intermetallic phases and the non-homogeneously distributed alloying elements in the cross-section of the rods or slabs and in the entire microstructure. The inhomogeneity of the chemical composition and the solid solution negatively affects the strength, the formability in the warm and the corrosion resistance, and can lead to the formation of undesired phases due to segregation in the material. In this experimental investigation, the cross-sections of the rods from two different alloys of the 6xxx group were investigated. From the cross-sections of the rods, samples for differential scanning calorimetry (DSC) at three different positions (edge, D/4 and middle) were taken to determine the influence of inhomogeneity on the course of DSC curve. Metallographic sample preparation was used for microstructure analysis, whereas the actual chemical composition was analysed using a scanning electron microscope (SEM) and an energy dispersion spectrometer (EDS).

CHEMICAL INTERACTION IN MIXTURES МF + NaBr (М – K, Rb, Cs) UNDER THERMAL ACTIVATION

The chemical interaction of equivalent amounts of MF+NaBr (M – K, Rb, Cs) was studied by differential thermal and X-ray phase analysis. A mechanism of interaction during thermal activation is proposed, including the formation of NaF+MBr products at the contact boundaries of the initial substance grains due to the diffusion of Na+ and M+ followed by contact melting of four substances that form a labile liquid phase below or equal to the melting points of low-melting triple eutectics. The labile liquid occurrence in the sample promotes rapid ionic interaction. The heating curves of equivalent amounts of two substance powdered mixtures corresponding to the unstable diagonals of triple irreversibly reciprocal systems made it possible to obtain data on the appearance of the liquid phase, the onset of exothermic reactions (the melting points of low melting eutectics), the melting temperatures of quasibinary eutectics on stable diagonals, and the melting temperatures of the mixtures. The crystallization of molten mixtures of equivalent amounts of two unstable substances of triple irreversibly reciprocal systems made it possible to determine the liquidus temperature at the point of complete conversion and the temperature of the crossing point on a stable diagonal. Therefore, the heating and cooling curves analysis provides information on the melting points of low-melting triple eutectics (570, 508 and 430 °C), the temperatures of the pass points (654, 644 and 606 °С) and the melting temperatures of the compositions corresponding to the full conversion points (798, 845 and ~840 °C) in the Na+,K+||F–,Br–, Na+,Rb+||F–,Br–, and Na+,Cs+||F–,Br– systems, respectively. Powdered substances exchange reactions can be used as low-potential exothermic compounds, as fuses, which turn off various reactors or plants when the liquid phase appears, and for the synthesis of inorganic substances.

The Effect of Doping of Lead with Lithium and Zinc with Strontium on the Kinetics and Phase Formation in a Number of Low-Melting Eutectic Systens User in Electronics and Heat-Transfer Agents

The effect of Li and Sr impurities on the kinetics and structure formation of alloys in the Sn - Pb, In - Zn, Sn - Zn systems used in the soldering of instrument nodes in electronics has been investigated. The XPS method showed that under the given experimental conditions and the indicated concentrations of lithium impurities in lead and strontium in zinc, there are no prerequisites for the formation of chemical compounds, which is explained by an insignificant impurity content, although a significant amount of chemical compounds is formed according to state diagrams. It was also established that impurities affect the kinetics of phase growth in the junction zone.