Eutectic Research Articles

Influence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures

Influence of Hydrogen Bond Acceptors and Water Content on Surface Tension in Glycol-Based Eutectic Mixtures

Phosphonium chloride-based deep eutectic solvents inhibit pathogenic Acanthamoeba castellanii belonging to the T4 genotype.

Herein, we investigated the anti-amoebic activity of phosphonium-chloride-based deep eutectic solvents against pathogenic Acanthamoeba castellanii of the T4 genotype. Deep eutectic solvents are ionic fluids composed of two or three substances, capable of self-association to form a eutectic mixture with a melting point lower than each substance. In this study, three distinct hydrophobic deep eutectic solvents were formulated, employing trihexyltetradecylphosphonium chloride as the hydrogen bond acceptor and aspirin, dodecanoic acid, and 4-tert-butylbenzoic acid as the hydrogen bond donors. Subsequently, all three deep eutectic solvents, denoted as DES1, DES2, DES3 formulations, underwent investigations comprising amoebicidal, adhesion, excystation, cytotoxicity, and cytopathogenicity assays. The findings revealed that DES2 was the most potent anti-amoebic agent, with a 94% elimination rate against the amoebae within 24h at 30°C. Adhesion assays revealed that deep eutectic solvents hindered amoebae adhesion to human brain endothelial cells, with DES2 exhibiting 88% reduction of adhesion. Notably, DES3 exhibited remarkable anti-excystation properties, preventing 94% of cysts from reverting to trophozoites. In cytopathogenicity experiments, deep eutectic solvent formulations and dodecanoic acid alone reduced amoebae-induced human brain endothelial cell death, with DES2 showing the highest effects. Lactate dehydrogenase assays revealed the minimal cytotoxicity of the tested deep eutectic solvents, with the exception of trihexyltetradecylphosphonium chloride, which exhibited 35% endothelial cell damage. These findings underscore the potential of specific deep eutectic solvents in combating pathogenic Acanthamoeba, presenting promising avenues for further research and development against free-living amoebae.

Preparation and heat storage characteristics of high-temperature phase change macrocapsules of chloride eutectic salt

Chloride salts, as high-temperature phase change materials (PCMs), have advantages in terms of high application temperature and high latent heat, but the intrinsic disadvantages such as high corrosiveness and easy leakage have seriously limited their development. Employing the NaCl–KCl binary salt as PCM, a double-shell cladding strategy with an inner layer of expanded graphite and an outer layer of ceramic was proposed, thereby, the chloride phase change macrocapsule with good thermal storage performance was successfully prepared. The double-shell capsules exhibited better leakage resistance and cycling stability. On this basis, the preparation process of double-shell eutectic salt macrocapsules was simplified by using an in-situ melting method, employing the mixed NaCl and KCl as raw materials directly that were transferred to eutectic binary salt inside the capsules during sintering. It is also proposed to improve the heat storage density of the capsules by increasing the capsule size and isostatically pressing the capsule. The NaK-20-200MPa sample indicated the largest heat storage density in the temperature range from 600 °C to 700 °C, with a mass heat storage density of 190.38 J/g, which was 2.85 % higher than that of the NaK-20-0MPa capsules and 36.99 % higher than that of the NaK-5-0MPa capsules. Additionally, the volume heat storage density of the NaK-20-200MPa capsules was 339.19 J/cm3, which was 14.69 % higher than that of the NaK-20-0MPa capsules and 21.52 % higher than that of the NaK-5-0MPa capsules. The good thermal performance and low cost of chloride PCM could ensure the encapsulated salt for use in high-temperature heat storage.

Microstructure and mechanical properties of pressure‐less sintered B4C–SiC–ZrB2–LaB6 ceramic composites

AbstractThe effect of LaB6 on the densification and microstructure of pressure‐less sintered 0.4B4C–0.4SiC–0.2ZrB2 ternary ceramic with eutectic composition was investigated. The Vickers hardness, bending strength, and fracture toughness of the quaternary ceramic were discussed based on the microstructural characteristics. The densification of the 0.4B4C–0.4SiC–0.2ZrB2 ceramic was enhanced with increasing LaB6 content from 0 to 70 mol% (the proportion to B4C–SiC–ZrB2). When the LaB6 content was 50 mol%, the densification rate of the composite ceramic reached a peak. The 0.27B4C–0.27SiC–0.13ZrB2–0.33LaB6 quaternary composite ceramic has reached a density of over 95% after being sintered at 2 100°C for 1 h. The B4C and SiC phases had refined grains of 1–3 µm with intragranular structures in the as‐sintered ceramics. The hardness and strength reached 17.9 ± .8 GPa and 307 ± 38 MPa, respectively. Crack deflection and branching were ascribed to the improved fracture toughness of 3.78 ± .26 MPa·m1/2. This study provides new ideas for fabricating dense non‐oxide ceramic composites with enhanced properties.

Impact of Aging Time on the Metallurgical Properties and Hardness Characteristics of an Al-Si-Mg-Cr Hypoeutectic Alloy Intended for Automotive Applications

This research investigates the microstructural evolution and mechanical properties of LM25 (Al-Si-Mg) alloy and Cr-modified LM25-Cr (Al-Si-Mg-Cr) alloy. Microstructural analysis reveals distinctive ε-Si phase morphologies, with Cr addition refining dendritic structures and reducing secondary dendrite arm spacing in the as-cast condition. Cr modification results in smaller-sized grains and a modified ε-Si phase, enhancing nucleation sites and reducing ε-Si size. Microhardness studies demonstrate significant increases in hardness for both alloys after solutionising and aging treatments. Cr-enriched alloy exhibits superior hardness due to solid solution strengthening, and prolonged aging further influences ε-Si particle size and distribution. The concurrent rise in microhardness, attributed to refined dendritic structures and unique ε-Si morphology, underscores the crucial role of Cr modification in tailoring the mechanical properties of aluminium alloys for specific applications.

Influence of the Rate of Cooling/Solidification on the Location of Characteristic Points on the AT and ADT Curves of Cast Iron

The paper presents the results of the analysis of cooling curves of cast iron with approximately eutectic composition rasterized at different rates of cooling and ingot crystallization. The test samples were in the form of rods with a diameter of 30,0.mm and a coagulation modulus M = 0.75 cm. They were cast in a sand mould made of furan mass placed on a chill in the form of a cast-iron plate, with which one of the front surfaces of the rod casting was in contact. In this way, a differentiated cooling rate along the rod was achieved. At selected distances from the chiller (5, 15, 25, 25 and 45 mm) thermocouple moulds were placed in the cavity to record the cooling curves used in thermal (AT) and derivation (ATD) analysis. The solidification time of the ingot in the part farthest from the chiller was about 200s, which corresponds to the solidification time in the test cup AT. An analysis of the recorded cooling curves was performed in order to determine the values of characteristic points on the AT curve (Tsol. Tliq, ΔTrecal., τclot, etc.). Relationships between cooling time and rate and characteristic points on AT and ATD curves were developed. For example, Tsol min changes in the range of 1115 - 1145 for the range of cast iron solidification times in the selected ingot zone from ~ 70 to ~ 200 s, which corresponds to the process speed from 0.0047 to 0.014 [1/s]. The work also includes an analysis of other characteristic points on the AT and ATD curves as functions of the solidification rate of cast iron of the same composition.

Microstructural evolution and mechanical property correlation in boron-added modified 9Cr-1Mo steel

Castable B-containing steels have immense manufacturing possibilities owing to their wide range of potential applications. This paper focuses on the microstructural evolution and its correlation with the mechanical properties of boron-added (0.5, 2.5, and 5 wt%) modified 9Cr-1Mo steel. A relatively lower quantity of B (0.5 wt%) results in a hypo-eutectic alloy with a ferrite matrix and borides at the prior austenite grain boundaries. Interestingly, this material exhibits even higher uniform ductility than the conventional 9Cr-1Mo martensitic steel. In contrast, the 2.5B system forms a near-eutectic microstructure, while the 5B has a hyper-eutectic microstructure with large boride phases, resulting in the formation of a ferrite-boride composite structure. The composite microstructure exhibits enhanced material strength with significant fracture resistance compared to the pure phase due to the presence of a relatively softer and ductile ferrite phase. The significant increase in uniform ductility of the 0.5B sample has been attributed to the local misorientation near the grain boundary gradient zone. Whereas, for the 2.5B and the 5B samples, the increased strength primarily stems from the second phase ((Fe,Cr)2B) strengthening. Such varied microstructures and properties can be tuned to suit desirable applications.

Density Measurements of Molten LiF-BeF2 and LiF-BeF2-LaF3 Salt Mixtures by Neutron Radiography.

The densities of eutectic (LiF)2-BeF2 and mixtures of this salt (FLiBe) with LaF3 were measured by dilatometry and by neutron attenuation from 673 K to 1,073 K. Because LaF3 has a limited solubility in FLiBe, it was necessary to determine the amount of LaF3 in solution before the density could be determined. The FLiBe density determination was favorably benchmarked against the literature data. A simple comparison was not available for the LaF3-FLiBe mixtures, so extrapolation of published data was necessary based on analysis using the Molten Salt Thermal Properties Database-Thermochemistry, or MSTDB-TC, developed by the US Department of Energy. Solubilities for LaF3 in FLiBe ranged from 1 to 4 mol % over 673 to 1,073 K. The salt system was heated and cooled over 24 h to evaluate potential changes in composition and hysteresis during the measurement. Changes in the meniscus were observed, and these were included in the correction for density determinations. Salt surface tension may have led to supersaturation of LaF3 in the salt because the solubility curve was nonlinear with respect to the inverse temperature, as would be expected for an ideal system. Surface tension measurements are currently underway to test this hypothesis.

Strategies to Prepare Chitin and Chitosan-Based Bioactive Structures Aided by Deep Eutectic Solvents: A Review

Chitin and chitosan, abundant biopolymers derived from the shells of crustaceans and the cell walls of fungi, have garnered considerable attention in pharmaceutical circles due to their biocompatibility, biodegradability, and versatile properties. Deep eutectic solvents (DESs), emerging green solvents composed of eutectic mixtures of hydrogen bond acceptors and donors, offer promising avenues for enhancing the solubility and functionality of chitin and chitosan in pharmaceutical formulations. This review delves into the potential of utilizing DESs as solvents for chitin and chitosan, highlighting their efficiency in dissolving these polymers, which facilitates the production of novel drug delivery systems, wound dressings, tissue engineering scaffolds, and antimicrobial agents. The distinctive physicochemical properties of DESs, including low toxicity, low volatility, and adaptable solvation power, enable the customization of chitin and chitosan-based materials to meet specific pharmaceutical requirements. Moreover, the environmentally friendly nature of DESs aligns with the growing demand for sustainable and eco-friendly processes in pharmaceutical manufacturing. This revision underscores recent advances illustrating the promising role of DESs in evolving the pharmaceutical applications of chitin and chitosan, laying the groundwork for the development of innovative drug delivery systems and biomedical materials with enhanced efficacy and safety profiles.

Neutronic analysis of a tokamak hybrid blanket cooled by thorium-molten salt fuel mixture

In this study, a novel approach has been investigated by using a mixture of thorium and molten salts as a dual-purpose coolant and medium for the production of fissile fuel in a Fusion Fission Hybrid Reactor (FFHR) for the reference geometry of ITER. The study highlighted the broader benefits of thorium fuel cycling, safety features, and reduced radioactive minor actinides generation. The use of a thorium-melted salt coolant for fissile fuel production in a fusion-fission hybrid reactor represented a promising path towards efficient and sustainable nuclear energy, with potential benefits in terms of safety features and reduced generation of radioactive minor actinides. In this study, SS 316 LN-IG was selected as the first wall material for the reactor, and a molten salt fuel mixture of LiF–ThF4 was used as the coolant, taking into account the eutectic points of the material, the nominal fusion power in the FFHR for the Tokamak design concept is considered to be 500 MW. The nuclear code MCNP6 was used with the nuclear data libraries ENDF/B-VIII and CLAW-IV for the neutron calculations. The time evolution of the isotopes in the reactor was calculated with the interface code MCNPAS. The study results are evaluated in terms of tritium breeding ratio, energy multiplication factor, radiation damage, fissile fuel production and fuel burn-up value.The 4-year operation history of total TBR value is calculated and always above 1.05 and increases with time.Th initially decreased from 631.3 tonnes to 587.2 tonnes, while 233U production during this period was 9.1 tonnes. According to these results, the first wall replacement period was calculated as 3.9 years.

Eutectic mixtures containing the active pharmaceutical ingredient ezetimibe: Phase diagrams, solid state characterization and dissolution profiles

Cardiovascular disease represents the leading cause of death worldwide, according to the World Health Organization (WHO) report. One of the treatment strategies is the use of the drug ezetimibe (EZT). This drug is a cholesterol absorption inhibitor with low aqueous solubility, which affects its therapeutic efficacy. The purpose of this paper was to obtain eutectic materials of EZT with methylparaben (MPB), salicylic acid (SCA) and nicotinamide (NTM) coformers, and to study their phase diagrams, dissolution properties and hygroscopicity to assess possible enhancements. Phase and Tamman diagrams were constructed using differential scanning calorimetry (DSC) results. The eutectic materials were characterized by powder X-ray diffraction (PXRD) and polarized light optical microscopy (OM). The hygroscopicity of the materials was assessed at different relative humidities (RH) through dynamic vapor sorption (DVS). The dissolution study was conducted with the materials in powder form, with paddle dissolution, rotating at 50 rpm, in 900 mL of aqueous buffer solution at pH 6.8 and 37 °C. The phase diagrams demonstrated that EZT formed eutectic systems with eutectic molar fractions of 0.59, 0.67 and 0.69 for EZT-SCA, EZT-NTM and EZT-MPB, respectively. The three eutectic materials are characterized as microcrystalline conglomerates of their components. In terms of the hygroscopic behavior of EZT at different RHs, eutectic materials demonstrated lower susceptibility to monohydrate formation compared to the anhydrous form. In dissolution studies, EZT-SCA and EZT-MPB solubilized EZT in amounts 22 % higher than the pure drug in 15 min. On the other hand, EZT-NTM eutectic suppressed the dissolution of EZT down to 56 % at the same time. The results indicated the possibility of obtaining materials with enhanced properties using eutectic mixtures, with improved dissolution rates and hygroscopic stability.

Clorine Solubility in Silicate Melts: New Experiments and Thermodynamic Mixing Model

We present new experimental data on Cl solubility in model basalt melts of eutectic compositions diopside (Di)–albite (Ab) and Di–anorthite ± quartz (Qtz). The starting glasses were equilibrated with aqueous fluid H₂O-NaCl-CaCl₂ at 4 kbar in the temperature range 900–1200°C. The experiments show that the Cl solubility decreases with increasing NaCl in the fluid. Ca-Na partitioning between melts and fluid is weekly temperature dependent and resembles that of the plagioclase-fluid system. The new experimental data, along with the previously published results on the model granite melting in the presence of (Na, K)Cl brines (Aranovich et al., 2013) are used to calibrate an empirical thermodynamic model for the salt species (NaCl, KCl, CaCl₂) in silicate melt. Calculations show that Cl solubility in the haplogranite melt decreases with increasing K/Na ratio in the fluid (and, correspondingly, melt). At high pressure (10 kbar) Cl solubility in the granite increases with increasing H₂O content. Calculated phase diagram for a simple pseudo-ternary system Ab–H₂O–NaCl demonstrates complex phase relations and, correspondingly, evolution of the H₂O and NaCl concentrations in the melt. Literature data on the variations of H₂O and NaCl in the melt and fluid inclusions in Qtz from the granite of Badzhal tin deposit is used to illustrate complex evolution of a fluid-magmatic system.

Thermophysical Properties of FUNaK (NaF-KF-UF4) Eutectics.

General interest in the deployment of molten salt reactors (MSRs) is growing, while the available data on uranium-containing fuel salt candidates remains scarce. Thermophysical data are one of the key parameters for reactor design and understanding reactor operability. Hence, filling in the gap of the missing data is crucial to allow for the advancement of MSRs. This study provides novel data for two eutectic compositions within the NaF-KF-UF4 ternary system which serve as potential fuel candidates for MSRs. Experimental measurements include their melting point, density, fusion enthalpy, and vapor pressure. Additionally, their boiling point was extrapolated from the vapor pressure data, which were, at the same time, used to determine the enthalpy of vaporization. The obtained thermodynamic values were compared with available data from the literature but also with results from thermochemical equilibrium calculations using the JRCMSD database, finding a good correlation, which thus contributed to database validation. Preliminary thoughts on fluoride salt reactor operability based on the obtained results are discussed in this study.

Synthesis and characterizations of random copolyamide PA(56-co-66): Excellent toughness and transparency

Random copolyamides PA(56-co-66) (coPA-n) with various comonomer compositions were synthesized by a one-pot polycondensation reaction of pentamethyleneammonium adipate (PMA) salt and hexamethyleneammonium adipate (HMA) salt in aqueous solution. All copolymers have high Mn (≥15000 g/mol). The molecular segment composition can be regulated by controlling the feed ratio of PMA salt and HMA salt. Tc and Tm of copolymers obtained by nonisothermal crystallization depend on the composition, showing a clear pseudo-eutectic behavior. Copolyamide coPA-50 exhibits a eutectic phenomenon with the melting point decreasing to a minimum of 218.9 °C. WAXD and SAXS results confirm that the crystalline structure of the copolyamides follows that of the rich component, exhibiting a typical isodimorphic characteristic. Mechanical properties of the copolyamides indicate that the elongation at break could be improved significantly with slight sacrifice of strength, which provides a promising approach for fabricating polyamide materials with desired properties. The tensile strength, tensile modulus, and elongation at break of coPA-50 was 65.2 MPa, 1.0 GPa, and 758.1 %, respectively. These copolymers can be melt-spun into fibers with excellent mechanical properties. Especially, the transmittance of coPA-60 reaches a high value of 88.01 % due to its low crystallinity and small crystal size.

The enhanced mechanical properties for Hf6Ta2O17 thin film through component segregation

With outstanding thermal and mechanical properties, Hf6Ta2O17 emerges as an ideal candidate for next-generation thermal barrier coatings (TBC) material. However, high-temperature process during TBC fabrication will inevitably lead to Ta2O5/HfO2 component segregation because large differences in vapor pressure. In this paper, Hf6Ta2O17 polycrystalline film with different Ta2O5/HfO2 component was prepared on sapphire substrate by sol-gel method through spin coating. Morphological analysis indicates the excessive Ta2O5 can reduce the porosity in Hf6Ta2O17 thin film through eutectic process, while excessive HfO2 will lead to a worse morphology and smaller average grain size. Nanoindentation reveals that component segregation of excessive Ta2O5/HfO2 could both be used to strengthen of Hf6Ta2O17 through different mechanisms. In addition, a higher elastic recovery rate in excessive Ta2O5 system indicates Ta2O5Hf6Ta2O17 eutectic system could accelerate energy dissipation and further enhance the toughness for Hf6Ta2O17. This work provides a deep insight into the strengthening mechanism of ceramics Hf6Ta2O17 with component segregation and paves the way to design of next-generation TBCs.

The Effect of Zr and Li on the Microstructure of AlMg5Si2Mn-Type Casting Alloys

AbstractIn the article, the authors present results of microstructural studies of Al-Mg-Si-Mn casting alloys with Zr, Li, and TiB2 additions on a broad scale. Zirconium content was set on two levels: 0.34 and 1.58 wt%, and Li was set 1.2 and 2.0 wt%. It was found that the addition of Zr shifts the eutectic melting temperature to a higher level, up to 611.3 °C at 1.6 wt% Zr. At the same time, Li addition leads to the depression of eutectic melting temperature: down to 587.2 °C at 2.0 wt% Li, what is a common effect of eutectic modification which was confirmed by means of structural examinations. The complex addition of Li and AlTi5B1 resulted in a eutectic melting temperature close to the equilibrium eutectic temperature for the Al-Mg-Si system (596.2 °C). The grain refinement effect of Zr is due to the nucleation of α-Al on the Zr(Al1−x, Six)3 phase. Crystals of this phase were detected in the grain centers of Zr-containing alloys. The Li addition does not affect α-Al grain size but changes the morphology of eutectic colonies from petal-like to fibrous. Observation of TiB2 particles inside the primary Mg2Si crystals gives direct experimental confirmation of nucleation of the primary phase on the surface of TiB2 in the alloy after adding Li and AlTi5B1. Natural aging of the alloys resulted in the formation of fine precipitates detected close to dislocations. The most apparent supposition is that the mechanism responsible for their formation is heterogeneous nucleation in the stress field of dislocations. Hardness tests showed adding 2.0 wt% of Li is very effective, increasing hardness up to 113 HV0.2 in naturally aged condition, which is nearly double that of commercial Al-Mg-Si die-casting alloy. Several effects were proposed which may synergistically contribute to the rise of hardness in Li-containing alloys, such as solid solution strengthening, formation of primary LiAlSi phase and natural aging.

Healing the structural defects of spinel MnFe2O4 to enhance the electrocatalytic activity for oxygen reduction reaction

Spinel metal oxides containing Mn, Co, or Fe (AB2O4, A/B = Mn/Fe/Co) are one of the most promising non-Pt electrocatalysts for oxygen reduction reaction (ORR) in alkaline conditions. However, the low conductivity of metal oxides and the poor intrinsic activities of transition metal sites lead to unsatisfactory ORR performance. In this study, eutectic molten salt (EMS) treatment is employed to reconstruct the atomic arrangement of MnFe2O4 electrocatalyst as a prototype for enhancing ORR performance. Comprehensive analyses by using XAFS, soft XAS, XPS, and electrochemical methods reveal that the EMS treatment reduces the oxygen vacancies and spinel inverse in MnFe2O4 effectively, which improves the electric conductivity and increases the population of more catalytically active Mn2+ sites with tetrahedral coordination. Moreover, the enhanced Mn-O interaction after EMS treatment is conducive to the adsorption and activation of O2, which promotes the first electron transfer step (generally considered as the rate-determining step) of the ORR process. As a result, the EMS treated MnFe2O4 catalyst delivers a positive shift of 40 mV in the ORR half-wave potential and a two-fold enhanced mass/specific activity. This work provides a convenient approach to manipulate the atomic architecture and local electronic structure of spinel oxides as ORR electrocatalysts and a comprehensive understanding of the structure-performance relationship from the molecular/atomic scale.

Clarification of two-parameter models for correlating grain size to phase diagram variables in hypoeutectic alloys

Simple two-parameter models were proposed for correlating grain size to process conditions and phase diagram variables. However, these models have not been fully examined using data obtained from well controlled experiments. This work intended to clarify these models with selected experimental data obtained in dilute hypoeutectic alloys. Criteria for data selected were proposed. The selected experimental data were fitted by these models to examine curve fitting quality and the applicability. Models that fit experimental data better were identified. Mechanisms by which grain size is reduced under the influence of a solute element were examined based on the data analysis. Results suggest that there is a clear dependence of grain size on the solidification interval of an alloy, which can be expressed as the P variable. Such a clear dependence of grain size on solidification interval indicates that mechanisms that are associated with dendrite fragmentation are the dominant operating mechanisms governing grain refinement by solute element in ingots and castings where convection in the molten alloy exists during its mold filling and solidification.

Investigation of interfacial properties of Ag–Cu/Si3N4 composite ceramic substrates by interface reaction of Si3N4 and CuO

The surface metallization of Si3N4 ceramics with the Ag–Cu conductive paste containing CuO was systematically investigated. The interfacial reactions between CuO and Si3N4 promoted the surface metallization of the ceramic substrate in an argon atmosphere. The effects of Ag and Cu relative contents on the evolution of the thick film surface morphology were studied. The electrical properties and tensile strength of composite ceramic substrates were enhanced through the generation of Ag–Cu eutectic solution within the thick film layer. The effect of brazing time on the properties of Ag–Cu/Si3N4 composite ceramic substrates was investigated. Mechanical testing and scanning electron microscopy (SEM) were used to analyze the interface tensile strength of the Ag–Cu/Si3N4 composite substrates and the morphology of the Ag–Cu film, and the bonding mechanism of the composite ceramic substrate was studied. When the sample was brazed at 800 °C for 20 min, the maximum tensile strength of 23.6 MPa between the Ag–Cu film and ceramic substrate was obtained, the lowest resistivity of 6.22 μΩ•cm was obtained. The bonding interface between thick film layer and the ceramic substrate formed the Ag–Cu mechanical structure was benefit for improving the comprehensive performance of the Cu/Si3N4 composite ceramic substrate.

High toughness and CMAS resistance of REAlO 3/RE 2Zr 2O 7 (RE = La, Nd, Sm, Eu, Gd, and Dy) composites with eutectic composition for thermal barrier coatings

High toughness and CMAS resistance of REAlO ₃/RE ₂Zr ₂O ₇ (RE = La, Nd, Sm, Eu, Gd, and Dy) composites with eutectic composition for thermal barrier coatings