Eutectic Crystallization Research Articles

Impact of solutionising temperature on the microstructure, hardness and tensile strength of Al-6.6Si-0.3Mg-3Ni alloys

The current research deals with the effect of solutionising temperature on the morphological behavior, hardness and tensile strength of Al-6.6Si-0.3Mg-3Ni alloys. In this work, the solutionising temperature was varied from 450 °C to 480 °C. The chemical composition of all cast samples was identified by using Arc Spectroscopy. The hardness of the cast samples was determined using the Vickers Hardness test. It was observed from the present investigation that, as solutionisation temperature increases, there observed a refinement in the gains of eutectic silicon crystals which enhanced the hardness and tensile strength values. The value of hardness and tensile strength was found to increase as the solutionized temperature increased. The heat-treated alloys under this investigation possessed superior hardness as compared to the LM25/A356 and as-cast alloy.

The Anti-Breast Cancer Effect and Mechanism of Glimepiride-Metformin Adduct.

BackgroundCompound adduct is a eutectic crystal formed by non-covalent bonds of two compounds or multiple compounds with water. Emerging evidence suggests that adduct could be different from the simple physical mixture of the individual compounds and has some new features. Recent studies reported that both glimepiride (Gli) and metformin (Met) may possess an anti-breast cancer effect besides anti-diabetic effect. In the current study, we synthesized glimepiride-metformin adduct (GMA) and examined its anti-breast cancer effect in vitro and in vivo to explore its potential in treatment of breast cancer in diabetic patients.MethodsGMA was synthesized from Gli, Met and water at a molar molecular mass of 1:1:1 and identified by infrared spectroscopy. MTT assay, colony formation assay and wound healing assay were performed to examine the effects of GMA on cell viability and migration of human breast cancer cell lines CAL-148, MDA-MB-453, MDA-MB-231and MCF-7. The effect of GMA on cell cycle and apoptosis was examined by flow cytometry. The orthotopic implantation model was established to observe the inhibitory effect of GMA on tumor growth. The expression of Ki67 was detected by immunohistochemistry. RT-qPCR and Western blotting were performed to investigate mechanisms for the function of GMA.ResultsBoth MTT and colony formation assays showed that GMA inhibited breast cancer cell viability, and the effect was greater than Gli alone, Met alone and the combination. In vivo study showed that GMA had an inhibitory effect on tumor growth of CAL-148 xenografts. Flow cytometry analysis indicated that GMA induced G1/S phase cell cycle arrest and apoptosis in breast cancer cells. RT-qPCR and Western blotting analyses showed that GMA activated AMPK, and up-regulated expression of p53 and p21, and down-regulated expression of cyclin D1 and CDK4.ConclusionGMA suppresses cell viability of breast cancer cells, and its effect is greater than Gli and Met alone or combination at the same concentration. GMA inhibits breast cancer cell growth in vivo. The antitumor effect of GMA may be related to the activation of AMPK resulting in up-regulation of p53 and p21 and down-regulation of cyclin D1 and CDK4.

Magnetoelectric Properties of Co1−xNixFe2O4/BaTiO3 Heterostructures with 3–3 Connectivity Obtained by Eutectic Crystallization

Multiferroic composites consisting of 62 mol% ferroelectric Ba0.97Sr0.03TiO3 and 38 mol% ferrimagnetic Co1–xNixFe2O4 with Ni substitution levels of x = 0, 0.25, 0.50, 0.75, and 1.00 are obtained from eutectic crystallization in a floating zone furnace. Scanning electron microscopy reveals the self‐organized formation of a 3–3 network. Epitaxy of the two phases is confirmed by single‐crystal X‐ray diffraction. All samples, except the one containing pure NiFe2O4, are free of impurity phases. The influence of the substitution level x on the unit cell parameters of both materials is investigated by Rietveld refinement before and after a reoxidation process in flowing oxygen at 1173 K. The amount of oxide defects is determined by thermal analysis, showing a nearly constant value throughout the whole Co1–xNixFe2O4 series. The effect of Ni substitution on the magnetic properties (saturation magnetization and magnetic transition temperature) of the eutectics is investigated. The magnetoelectric (ME) properties of the samples are studied in dependence on the DC field (HDC), the frequency of the AC field (HAC), and temperature. The Ni content has a strong influence on the absolute value of the ME coefficient (αME), but only a slight effect on the general behavior of the ME properties.

Study of progressive freeze concentration and eutectic freeze crystallization technique for salt recovery

In this industrial era, salt recovery from seawater has become an important issue from the environment perspective. Few freezing technologies have been proposed as capable way to separate the salt from the seawater because of the energy used in the previous technologies is higher. A study of Progressive Freeze Concentration (PFC) and Eutectic Freeze Concentration (EFC) method have been carrying out and further investigated on their performance in recovering the salt. For the PFC method, pure water crystallizes into crystal and the concentrate is left behind as in liquid form while for the EFC method, both ice crystals and salt crystallize at the same time when the initial concentration of water salt mixture is exactly the same as eutectic concentration. In EFC, salt sinks to the bottom while ice floats at the top of the crystallizer and both are separated by gravity separation. Effective partition constant and solute recovery are calculated to evaluate the efficiency of PFC and EFC. In this study, the PFC method has shown an effective partition constant of 0.28 and recovered solute of 0.88 g of sodium chloride per 1 g of initial sodium chloride while for EFC method, effective partition constant and solute recovery obtained are 0.59 and 0.66. Overall, both techniques are applicable for the seawater desalination process.

Comparative Study on Mixing Behavior of Binary Mixtures of Cocoa Butter/Tristearin (CB/TS) and Cocoa Butter/Coconut Oil (CB/CO).

The comparative study between the mixing behavior of two binary mixtures of cocoa butter (CB)/tristearin (TS) and cocoa butter (CB)/coconut oil (CO) was investigated by using differential scanning calorimetry (DSC). The DSC profile for CB/TS blends resulted in a monotectic temperature–concentration (T–X) phase diagram, whereas a phase diagram of eutectic type was observed for CB/CO blends at 65 wt % of CO and 35 wt % CB; this suggests that the eutectic crystal can be formed when the saturated fat (blue = CO) is smaller in size compared to monounsaturated fat (orange = CB), whereas, for similar and larger size (red = TS) to CB, phase separation under crystallization is likely to occur (as shown in the graphical abstract). In order to understand the interaction between the binary systems, the profile of the phase diagram was fitted with Bragg–Williams approximation for estimation of the nonideality mixing parameter. Moreover, the morphology of the two different systems by polarized light microscopy (PLM) also depicted the variations in phase behavior by showing a significant change in CB morphology from spherulitic, grainy to granular and needlelike after the addition of TS and CO, respectively. Our findings emphasize the fundamental understanding of the interaction of bulk fat/fat and fat/oil system.

Heat source of the 2014 phreatic\xa0eruption of Mount Ontake, Japan

We present petrological evidence of the shallow magmatic processes that may have supplied heat and gas to the eruption of Mount Ontake, Japan, on 27 September 2014, which resulted in 63 fatalities. Ash from the eruption comprises primarily hydrothermally altered, white-toned rock fragments. However, the ash contains trace amounts (< 0.7 wt%) of vitreous less-altered particles (LAPs), which are only altered on their surfaces, suggesting rapid ascent through the hydrothermal system. The LAPs are classified into two categories: “glassy” and “crystalline.” Glassy LAPs comprise high-silica rhyolitic glass (74–83 wt% SiO2) with rounded quartz, chalcedony-free vesicles, and reversely zoned plagioclase (cores = 47 mol% An; rims = 70 mol% An), indicating magma re-heating. Crystalline LAPs have a groundmass-like texture that suggests eutectic crystallization at shallow depths. Thermodynamic calculations indicate that the pre-eruptive temperatures of the glassy and crystalline LAPs were 700–1300 °C and ~ 700 °C, respectively, and that the storage depth was < 4 km (pressure < 100 MPa). The observed petrological features suggest that the LAPs were sourced from a magma recently intruded at shallow depths. Although crustal deformation (i.e., the volume change associated with magmatic intrusion) was insignificant prior to the 2014 eruption, a clear signature of crustal deformation was observed in 2007, the source of which was located 3 km below the summit. We suggest that the magma that was intruded 3 km below the summit in 2007 supplied the heat and gas for the 2014 phreatic eruption.

Effects of Al-5Ti-0.62C-1.07La intermediate alloy on the microstructure and mechanical properties of A356 aluminum alloy

The physical characters that belong to hypo-eutectic Al-Si alloys are affected by certain important factors including the dimension, distribution together with structure of eutectic Si crystals together with primary α-Al. In this paper, A356-x Al-5Ti-0.62C-1.07La (x = 0, 4, 5, 6, 7 wt%) alloys are was prepared by mechanical stirring. The effects of Al-5Ti-0.62C-1.07La intermediate alloy on the microstructures and mechanical properties of A356 alloy are investigated. Results show that the primary α-Al was significantly refined by Al-5Ti-0.62C-1.07La intermediate alloy. The secondary dendrite arm space (SDAS) of unrefined α-Al is approximately 40 μm. When the substance of Al-5Ti-0.62C-1.07La intermediate alloy is 6 wt%, SDAS declines to 10 μm. In addition, the component part of eutectic Si turns from thick acicular/schistose to short rod-like together with a section of pellets. Adding 6 wt% Al-5Ti-0.62C-1.07La intermediate alloy, A356-T6 alloy obtained the best tensile function and hardness. The ultimate tensile strength (UTS), elongation (El) together with Vickers hardness (HV) are 183.5 MPa, 8.2% and 62.3, which is increased by 30.3%, 95.2% and 38.1%, respectively. Furthermore, the variation in mechanical properties change with the development of micro-structure.

Phase diagram of BaI2-LuI3 system and growth of BaI2/LuI3 eutectic scintillator

Abstract The phase diagram of the BaI2-LuI3 system was created using powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis, and a eutectic scintillator crystal was grown by the halide-vertical bridgman (H-VB) method. The results of XRD patterns and DSC curves showed that the phase diagram of the BaI2-LuI3 system had a eutectic point around 77.5 mol% BaI2/22.5 mol% LuI3, and no new compound was generated from BaI2 and LuI3. The 77.5 mol% BaI2/22.5 mol% LuI3 eutectic crystal was composed of BaI2 in rod phase and LuI3 in matrix phase. In addition, the Ce-doped 77.5 mol% BaI2/22.5 mol% LuI3 specimen showed emission peaks originating from 5d–4f transition of Ce3+ ion in the X-ray radioluminescence (XRL) spectrum and the decay time under γ-ray irradiation was approximately 38 ns.

Eutectic freeze crystallization of saline dairy effluent

The disposal of saline effluent in the dairy industry is subject to increasingly strict regulatory requirements. In this work, eutectic freeze crystallization (EFC) was investigated as a mechanism for the simultaneous separation of salts and ice in a typical saline effluent, namely salty whey. Experiments were conducted using salty whey samples collected from a dairy processing facility. The eutectic point of the salty whey was determined using differential scanning calorimetry and was found to be lower than that of NaCl solutions (−24 °C for salty whey vs. −21 °C for aqueous NaCl solutions). Crystallization experiments were then used to construct the phase diagram of this dairy stream under equilibrium conditions. The change in cation composition in the supernatant at the eutectic temperature was measured as a function of time and showed that pure NaCl salts and ice formed within 5 min after this temperature was reached. The energy consumption of this process was estimated to be ~120 kWh/t for salty whey, which is comparable to that for conventional thermal crystallization of brine.

Increasing Wear Resistance of Chizel Tools Working Bodies Based on Improving the Metallographic Structure of Grey Cast Iron

The article concerns developing and implementing the technological principles for manufacturing the working bodies of chisel tools by casting grey cast iron with partial chilling of its working edges and surfaces interacting with the soil layer. High wear resistance of the working body is achieved by chilling its working part by means of a chill inserted into the mold, or by absence of coating in the corresponding zone of the mold. Severe overcooling of liquid cast iron contacting the chill or the metal surface of the mold causes crystallization of the meta-stable eutectics, and in the chilled part it acquires a ledeburite structure, the hardness being not lower than 64 HRC. At the same time, the bulk of the cast iron crystallizes in the stable system, forming austenitic-graphite eutectics and after complete cooling, it should have a pearlitic metal base, ensuring good machine ability of casting by cutting. Working surfaces and cutting edges of chisels are exposed to abrasive and chemical impacts of the soil, causing intense wear, the latter being the main reason for their failure. The utilization of the given technology will allow increasing service-life of the working bodies and improve the manufacturability, according to the criteria for labor intensity and casting mold making.

Physicochemical Principles Underlying the Synthesis of Granular Semiconductor–Ferromagnet Magnetic Structures Exemplified by AIIGeAs2 (AII = Zn, Cd) Materials

This paper presents an analytical review that addresses physicochemical principles underlying the synthesis of granular structures in semiconductor–ferromagnet systems. Such systems comprise a II–IV–V2, II2–V3, or II–V2 compound as a semiconductor and MnAs as a ferromagnet. We demonstrate that granular magnetic structures are an alternative to superlattices in spintronic devices and can exhibit giant magnetoresistance and tunneling magnetoresistance effects. It is shown that, owing to the high carrier mobility in semiconductors, they are more attractive as matrices of granular materials than are metals or dielectrics. We have formulated the basic principles underlying the synthesis of granular structures with high magnetoresistance based on eutectic systems. Eutectic crystallization involves simultaneous crystallization of all the constituent phases, leading to the formation of an unusual, fine structure. High cooling rates are favorable for metastable crystallization. This causes a synergistic effect, stimulating nanostructuring and favoring the formation of granular structures. We present results on semiconductor–ferromagnet systems and demonstrate the possibility of producing granular magnetic structures with high magnetoresistance in such systems.

Vitrification and increase of basicity in between ice Ih crystals in rapidly frozen dilute NaCl aqueous solutions.

The freezing of ionic aqueous solutions is common in both nature and human-conducted cryopreservation. The cooling rate and the dimensions constraining the solution are known to fundamentally influence the physicochemical characteristics of the sample, including the extent of vitrification, morphology, and distribution of ions. The presence of some salts in an aqueous solution often suppresses the ice crystallization, allowing bulk vitrification during relatively slow cooling. Such a process, however, does not occur in NaCl solutions, previously observed to vitrify only under hyperquenching and/or in sub-micrometric confinements. This work demonstrates that, at freezing rates of ≥100 K min-1, crystallized ice Ih expels the freeze-concentrated solution onto the surfaces of the crystals, forming lamellae and veins to produce glass, besides eutectic crystallization. The vitrification covers (6.8% ± 0.6%) and (17.9% ± 1.5%) of the total eutectic content in 0.06M and 3.4 mM solutions, respectively. The vitrified solution shows a glass-to-liquid transition succeeded by cold crystallization of NaCl · 2H2O during heating via differential scanning calorimetry. We establish that ice crystallization is accompanied by increased basicity in freeze-concentrated solutions, reflecting preferential incorporation of chloride anions over sodium cations into the ice. After the sample is heated above the glass transition temperature, the acidity gradually returns towards the original value. The morphology of the samples is visualized with an environmental scanning electron microscope. Generally, the method of vitrifying the freeze-concentrated solution in between the ice Ih crystals via fast cooling can be considered a facile route towards information on vitrified solutions.

Magnetoelectric and HR-STEM investigations on eutectic CoFe2O4–Ba1–xSrxTiO3 composites

Multiferroic Ba1–xSrxTiO3–CoFe2O4 (x = 0.03, 0.05) composites with rarely investigated 3-3 connectivity were prepared by eutectic crystallization in an optical floating zone furnace. High-resolution scanning transmission electron microscopy investigations of the CoFe2O4–BaTiO3 interface revealed an almost perfect connection between both components. These micrographs also showed that the impact of post-annealing in air was much larger than expected and resulted in formation of small BaTiO3 inclusions in the CoFe2O4 phase. The magnetoelectric coefficient αME was studied in detail with respect to its dependence on the static magnetic field, the frequency of the driving AC-field and temperature. Furthermore, the influence of different growth rates (5, 10 and 20 mm h−1), chemical composition, sample thickness and the alignment of electrical polarization and magnetic field (collinear or vertical) on the magnetoelectric properties were studied. The largest value of αME = 1.3 mV Oe−1 cm−1 was found for a sample grown at 5 mm h−1. For even slower growth rates, a higher Sr content was required to avoid the formation of impurity phases leading to a decrease of αME.

Thermal Property Characterization of a Low Supercooling Degree Binary Mixed Molten Salt for Thermal Energy Storage System

In this paper, LiNO3–NaCl binary mixed molten salt with high phase change enthalpy was selected as phase change materials (PCM). LiNO3 was used as the main phase change material, and NaCl was used as the additional material to change the properties and reduce the supercooling degree of molten salts. LiNO3–NaCl binary mixed molten salts with different mass proportion were prepared by static melting method. The optimum eutectic ratio of the mixed molten salt was obtained through analysis of the experiment results. The influence of NaCl on phase change temperature, decomposition temperature, supercooling degree and phase change latent heat were tested and analyzed. The properties of the phase change materials were characterized by thermogravimetric analyzer and simultaneous differential scanning calorimeter (TGA/DSC), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The phase transition temperature, latent heat and supercooling degree of the binary mixed molten salts showed nonlinear variation with the increase in NaCl mass fraction. When the mass ratio was 88:12 for LiNO3–NaCl, the phase change temperature was the lowest of 222.6 °C, the phase change latent heat was the highest of 389.3 J·g−1 and the supercooling degree was 1.2 °C. The optimum eutectic crystallization degree was achieved. At the same time, the decomposition temperature of the mixed molten salt was increased from 560 °C to 620 °C with the addition of NaCl, which greatly increased the applicable temperature range of LiNO3.

Investigations into ice scaling during eutectic freeze crystallization of brine streams at low scraper speeds and high supersaturation

Eutectic Freeze Crystallization (EFC) is a potentially cost-effective method to treat reverse osmosis (RO) brines, through the simultaneous crystallization of ice and salt. A major operational challenge, limiting the implementation of EFC in industry, is the formation of an ice scale layer on heat exchanger surfaces. This research determined the influence of the heat transfer driving force, hydrodynamics and brine composition on the severity of ice scaling during continuous EFC of a Na2SO4-H2O system. Experiments were conducted in a hybrid crystallizer-separator with a scraped 2 L crystallization zone. The research focussed on high heat transfer driving forces and slow scraping rates. A unique induction time for scale formation was observed for each set of process conditions. The induction time increased with the increase in scraper speed and decreased as the heat transfer driving force increased. The increase in induction time at higher rotational Reynolds number was attributed to faster distribution of supersaturation, as the flow regime became more turbulent, and more efficient scraping of ice off the wall. The scaling potential decreased as the magma density increased until a certain threshold was reached where it increased again due to the solids impeding effective mixing and heat transfer. Scaling tendencies were reduced during crystallization of multi-component brine streams as compared to binary streams.

Growth behavior of Zn-rich phase in Zn-Mg alloy under a high magnetic field

In Zn-based alloys, Zn-rich phase is generally one of the most important structural components formed during the solidification process. However, little work has been done to investigate and control particularly the growth behavior of Zn-rich phase, which usually plays an important role in determining the structures and the final properties of the alloys. Based on this, Zn-Mg alloy was solidified under different high magnetic fields (HMFs) in this work. The results show that, irrespective of whether the HMFs are imposed or not, the primary Zn-rich crystals prefer growing along 101¯0 in the {0001} basal plane and along 〈0001〉 in the {1¯21¯0} plane, and finally form less- or well-developed dendrites with strong morphological anisotropy in three dimensions. Due to the magnetocrystalline anisotropy, however, the HMFs tend to orient the primary Zn-rich crystals preferentially with the c-axis perpendicular to the HMFs direction (i.e., tend to produce {0001} basal texture) and thus to align them with the longer axes parallel to the HMFs direction. The eutectic Zn-rich crystals follow the orientations of their adjacent primary crystals and then also develop {0001} basal texture under a high magnetic field. In addition, correlated with the orientations and the anisotropic morphology, the primary Zn-rich crystals exhibit various two-dimensional shapes in the longitudinal and transverse sections of the specimens.

The mechanism of eutectic modification by trace impurities

In the quest toward rational design of materials, establishing direct links between the attributes of microscopic building blocks and the macroscopic performance limits of the bulk structures they comprise is essential. Building blocks of concern to the field of crystallization are the impurities, foreign ingredients that are either deliberately added to or naturally present in the growth medium. While the role of impurities has been studied extensively in various materials systems, the inherent complexity of eutectic crystallization in the presence of trace, often metallic impurities (‘eutectic modification’) remains poorly understood. In particular, the origins behind the drastic microstructural changes observed upon modification are elusive. Herein, we employ an integrated imaging approach to shed light on the influence of trace metal impurities during the growth of an irregular (faceted–non-faceted) eutectic. Our dynamic and 3D synchrotron-based X-ray imaging results reveal the markedly different microstructural and, for the first time, topological properties of the eutectic constituents that arise upon modification, not fully predicted by the existing theories. Together with ex situ crystallographic characterization of the fully-solidified specimen, our multi-modal study provides a unified picture of eutectic modification: The impurities selectively alter the stacking sequence of the faceted phase, thereby inhibiting its steady-state growth. Consequently, the non-faceted phase advances deeper into the melt, eventually engulfing the faceted phase in its wake. We present a quantitative topological framework to rationalize these experimental observations.

Recovering sodium erythorbate from wastewater through freeze crystallization technology.

Eutectic freeze crystallization was developed to recover sodium erythorbate (NaE) from wastewater at pHs 4.1, 5.3, and 6.5. Two substances (A and B) were sequentially recovered from the samples. The recovery rate of substance A was 2.06, 1.83, and 3.03g/L at pHs 4.1, 5.3, and 6.5, respectively; while that of B was 5.51, 3.09, and 3.26g/L at the corresponding pHs. The analysis results of the two recovered substances indicated that substance A was mostly Na2 SO4 ·10H2 O, while substance B was mainly NaE. Salt recovery was most successful at pH 4.1 with the purity of recovered NaE reaching 87.53wt%. Moreover, the chemical oxygen demand and electric conductivity of the ice were far smaller than the initial wastewater. The concentration effect was minimal due to the formation of Na2 SO4 ·10H2 O and NaE crystals. This combined crystallization strategy can potentially become an economic technology to recover NaE from wastewater. Practitioner points Segregation of NaE and Na2 SO4 ·10H2 O during the freeze crystallization process. Recovering 5.53kg NaE with the purity of 87.53wt% from 1m3 wastewater. Decreasing chemical oxygen demand and electric conductivity of wastewater through freeze crystallization technology.

Structure of the Al90Y10 Alloy Formed upon Pressure Solidification

The effect of temperature and the melt cooling rate on the structure of an Al90Y10 alloy after high-pressure solidification is comparatively studied by X-ray diffraction analysis, optical microscopy, and electron microscopy. Only the crystalline α-Al and Al3Y phases form in the Al90Y10 alloy under all considered solidification conditions. The effect of the temperature, the cooling rate, and the pressure on the morphology, the size, and the microhardness of the structural alloy constituents, such as primary yttrium aluminide and eutectic crystals, is found.

Non-Equilibrium Crystallization of a Eutectic Alloy - Mathematical Model

The process of a eutectic alloy crystallization is considered when the eutectic alloy is instantly cooled from the liquid state to below the eutectic transformation temperature. The features of such crystallization are considered. The mathematical model of the process is constructed that takes into account the nucleation of new phases particles, their growth and the associated change the concentrations of the melt components. The nuclei of new phases are supposed be spherical. As they grow, they come into contact and become lamellar. The developed approach was applied to the amorphization process of the eutectic alloys. An amorphous state has been reached if the clusters of solid phases can’t grow above nanosize. The model allows researching the necessary amorphization conditions.