Eutectic Melting Temperature Research Articles

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.

Gold and silver: Noble solvents for the synthesis of superconducting boron-doped diamonds

The synthesis of diamonds in traditional growth systems based on Fe, Co and Ni does not allow overcoming the semiconductor level of boron doping of diamond, presumably because of a high affinity of boron to boride-forming metals. For the first time, noble metals that do not form borides—silver and gold—are used as growth media for the synthesis of heavily boron-doped diamonds at 8–9 GPa. Gold and silver are not catalysts for the transformation of graphite to diamond, whereas elemental boron is catalytically active at eutectic melting temperatures above 2500 K. It is found that the synthesis of diamond in AgB and AuB growth media starts at temperatures close to the melting temperatures of Ag and Au, 1600 and 1800 K, respectively. Calculations show that molten Au and Ag dissolve boron atoms without a significant change in the electronic structure of the solution, suggesting that the metal melts serve as a carrier for the boron catalyst. The resulting polycrystalline diamond contains dispersed inclusions of Ag and Au, as well as traces of boron carbide; the formation of borides is not detected. The transport measurements of the diamond samples reveal a transition to a superconducting state in the temperature range from 4.5 to 2.5 K. Raman spectroscopy confirms the heavy boron doping of diamond. Thus, we show that melts of “non-catalytic” metals that do not form borides can be effectively used to synthesize boron-doped conductive/superconducting diamonds at relatively low temperatures.

Experimental investigation on nucleating agent for low temperature binary eutectic salt hydrate phase change material

The melting enthalpy and melting temperature have a significant impact on the latent heat that results from phase change materials (PCMs) used for thermal energy storage. Among the PCMs that are currently on the market, inorganic salt hydrates have greater thermal conductivity and latent heat than organic PCMs. However, the problem of salt hydrates' degree of supercooling limits their use in energy storage devices. Using sodium carbonate decahydrate (SCD) and sodium phosphate dibasic dodecahydrate (SPDD), a low temperature inorganic-inorganic eutectic salt hydrate PCM with a higher melting enthalpy and intended phase transition temperature is developed in this research study. The eutectic SCD/SPDD salt hydrate PCM eutectic point and the eutectic composition of salt hydrate PCMs to operate at low temperature range is numerically determined using Schrader equation. By numerical methods we obtain the 68 wt% of SCD with 32 wt% of SPDD to exhibit eutectic SCD/SPDD composite with eutectic melting temperature of 26.2 °C and melting enthalpy of 210.6 J/g. The synthesised eutectic PCM are characterised to explore their chemical stability, latent heat, melting point and their shortcoming due to degree of supercooling. A good way to get around the problem of the supercooling degree is to disperse the nucleating agents. In order to assess the type and degree of supercooling, the produced eutectic PCM composition is experimentally evaluated at 1–10% utilising borax, alumina, and sodium sulphate dodecahydrate as nucleating agents. However, for building cooling applications PCM with minimal degree of supercooling, with the ability to release low enthalpy during discharging is an advantage.

Zinc Nitrate Hexahydrate Pseudobinary Eutectics for Near-Room-Temperature Thermal Energy Storage.

Stoichiometric salt hydrates can be inexpensive and provide higher volumetric energy density relative to other near-room-temperature phase change materials (PCMs), but few salt hydrates exhibit congruent melting behavior between 0 and 30 °C. Eutectic salt hydrates offer a strategy to design bespoke PCMs with tailored application-specific eutectic melting temperatures. However, the general solidification behavior and stability of eutectic salt hydrate systems remain unclear, as metastable solidification in eutectic salt hydrates may introduce opportunities for phase segregation. Here, we present a new family of low-cost zinc-nitrate-hexahydrate-based eutectics: Zn(NO3)2·6(H2O)-NaNO3 (Teu = 32.7 ± 0.3 °C; ΔHeu = 151 ± 6 J·g-1), Zn(NO3)2·6(H2O)-KNO3 (Teu = 22.1 ± 0.3 °C; ΔHeu = 140 ± 6 J·g-1), Zn(NO3)2·6(H2O)-NH4NO3 (Teu = 11.2 ± 0.3 °C; ΔHeu = 137 ± 5 J·g-1). While the tendency to undercool varies greatly between different eutectics in the family, the geologic mineral talc has been identified as an active and stable phase that dramatically reduces undercooling in Zn(NO3)2·6(H2O) and all related eutectics. Zn(NO3)2·6(H2O) and its related eutectics have shown stability for over a hundred thermal cycles in mL scale volumes, suggesting that they are capable of serving as robust and stable media for near-room-temperature thermal energy storage applications in buildings.

A framework to predict binary liquidus by combining machine learning and CALPHAD assessments

Knowledge of the liquidus is important for the design and processing of many materials. For instance, deep eutectics are important for the design of metallic glasses, and recently multi-principal element alloys have been designed based on eutectic compositions or melting temperatures extrapolated from binary liquidus data. In this study, we provide a general framework for predicting binary liquidus only from the properties of the pure elements and thermodynamic properties calculated by Miedema’s model. Our framework combines three machine learning models that are trained and evaluated on liquidus data collected from 466 CALPHAD assessments of binary phase diagrams. The first model predicts the formation of liquid miscibility gaps with a prediction accuracy of 95.3%, outperforming the empirical Mott model. The second and third models predict the equilibrium onset temperature of solidification and the critical temperature of liquid miscibility gaps, respectively. An important feature of our models is that they can give indications of the presence of congruent melting phases and eutectics. Using our framework, we predict the liquidus in 1563 binary systems not included in our CALPHAD dataset, many of which are unknown. By collecting more data, our framework will continue to grow towards better liquidus prediction.

Molecular insights into potential hydrophobic deep eutectic solvents for furfural extraction guided by COSMO-RS and machine learning

In this study, we aimed to gain molecular insights into the potential of hydrophobic deep eutectic solvents (HPDESs) as solvents for furfural extraction. To achieve this, we screened 108 HPDES constituents using the quantum chemical COSMO-RS method, saving time and resources. Moreover, the σ-profiles of the HPDES constituents were analyzed using machine learning techniques, including decision trees and multilinear regression, to understand their impact on extraction performance. Our results showed that the top 5 HPDES constituents were 3–5-di-tertbutylcatechol, 1-naphthol, p-hydroxybiphenyl, phenol, and thymol, indicating that aromatic-based solvents containing a phenolic hydroxyl group are ideal for furfural extraction. Building on this, we used the COSMO-RS method to predict the eutectic composition and melting temperatures of the top 10 binary HPDESs, composed of the top 5 pre-screened constituents. These HPDESs were then evaluated for furfural extraction under typical hemicellulose treatment conditions. Our findings showed that these HPDESs were highly effective for furfural extraction, achieving performance comparable to industry benchmarks while avoiding the high volatility associated with these benchmarks.

In situ solidification of eutectic Al-33wt%Cu droplets

Al-33wt%Cu eutectic droplets were rapidly solidified using Impulse Atomization, a drop tube technique. The samples were then processed in situ in an SEM using an HTN-0101 MEMS heating chip manufactured by Norcada. The temperature of the chip, as well as the heating and cooling rates, can be easily set using the chip’s control software, allowing for heating and cooling rates as fast as 1000°C/second. The droplets were heated above the eutectic melting temperature. Thanks to the oxide skin, the droplets retained their spherical shape, which allowed in situ solidification experiments. The live feed of the surface of the droplet obtained with the SEM was recorded during the experiments alongside the temperature-time profile. Various cooling rates were imposed and the liquid samples were shown to undercool prior to solidification. The resulting eutectic morphologies and spacings were then analyzed as a function of the cooling rates and undercoolings.

Exploring Ru Compatibility With Al-Ge Eutectic Wafer Bonding

We explore compatibility of Ru with Al-Ge eutectic wafer bonding. We first present experiments to check for the presence of Ru ternary alloy poisoning inhibiting Al-Ge melting as well as evaluations of Al-Ge melt wettability on Ru and diffusion outcomes following bond-simulating anneals. Results show that Ru is stable with no observed microstructural changes or dissolution in the melt, indicating no ternary poisoning for the applied thermal budget. Ru was found to act as an effective barrier offering good melt wettability in all considered configurations with Al and Ge. From inspection of the binary constituents of Al-Ge-Ru we propose that Al-Ge eutectic melting temperature will decrease marginally for Ru contamination in a 1-2% range before a drastic increase in melting temperature (>10°C/% Ru) at higher Ru compositions. We then demonstrate wafer-level packaged 200 mm devices and MEMS with strong bond outcomes of devices bearing Ru contacts. We conclude that Ru has high compatibility with Al-Ge eutectic bonding. [2022-0037]

Melting of the Fe‐C‐H System and Earth's Deep Carbon‐Hydrogen Cycle

AbstractThe occurrences and cycling of slab‐originated carbon and hydrogen are considered to be controlled by their reactions with metallic iron from mantle disproportionation and slab serpentinization, to form Fe alloys containing carbon and hydrogen. Here we show experimental results on the phase relations and melting of the Fe‐C‐H system using laser‐heated diamond anvil cell and X‐ray diffraction techniques up to 72 GPa. The incorporation of hydrogen was found to lower the eutectic melting temperatures of Fe‐C alloy by ∼50–178 K at 20–70 GPa, facilitating the formation of metallic liquids in the deep mantle and thus enhancing the mobility and deep cycling of subducted carbon and hydrogen. Hydrogen also substitutes with carbon in Fe‐C metal to form hydride and diamond at relatively high‐temperature conditions (e.g., 42.6 GPa, >1885 K and 71.8 GPa, >1798 K). The hydrogen‐carbon‐enriched metallic liquids provide the necessary fluid environment for superdeep diamond growth.

The mechanical property of different morphology Ti-Ni solder in brazing of BN ceramic and stainless steel

BN ceramic and stainless steel metal had been connected by vacuum brazing technology. The surface morphology and the micro-structure of solder were observed by optical microscope and scanning electron microscope. The mechanical property of solder was tested by the experiment. The experimental results show that: titanium powder/ Ni powder alloy solder can not form a valid connection due to osteoporosis and porous surface after high temperature heating. Ti powder /Ni foil solder can produce certain effects of connection, but BN ceramic occurs exfoliation in the process of cooling. Because of the affection of impurity elements, eutectic melting temperature of Ti-Ni based solder decreases, and the multiple solder alloy has formed with high density.

Electrodeposition of ternary Sn-Cu-Ni alloys as lead-free solders using deep eutectic solvents

The paper presents several experimental results regarding the electrodeposition of Sn-Cu-Ni ternary alloys as an attractive lead-free solder candidate, involving deep eutectic solvents (DESs), namely using choline chloride-ethylene glycol and choline chloride-malonic acid eutectic mixtures. The influence of the metallic ions concentration in the electrolyte and of the applied current density on the Sn-Cu-Ni alloy composition and morphology has been investigated, in order to achieve the corresponding alloy composition (Sn99.4Cu0.6 alloy + Ni) able to possess the eutectic or near eutectic melting temperature of about 227 °C. Adherent, bright and uniform Sn-Cu-Ni alloy deposits have been obtained onto Cu substrate from choline chloride-ethylene glycol-based electrolytes for applied current densities between 5–8 mA.cm−2 at 60 °C. According to the TGA measurements, values of melting point of 229 °C have been obtained, corresponding to an alloy stoichiometry of Sn99.29-Cu0.65-Ni0.06 as indicated by EDX elemental analysis. In addition, analysis of the current-time curves using the Scharifker-Hills’ model suggested that the alloy deposition process corresponds to a nucleation and tridimensional growth controlled by diffusion mostly under instantaneous nucleation. Preliminary results related to the solder joints behavior showed adequate solderability characteristics and adhesion to the substrate with no fractures. Moreover, the electrodeposited Sn-Cu-Ni (Sn99.29-Cu0.65-Ni0.06) alloy coatings exhibited a slightly better corrosion performance as compared to Sn-Ni alloys electrodeposited from DESs and to the metallurgically prepared lead-free solders possessing a relatively similar composition.

Halogen Bonding in Dithiane/Iodofluorobenzene Mixtures: A New Class of Hydrophobic Deep Eutectic Solvents

AbstractWhile research into deep eutectic solvents (DESs) has expanded over the previous two decades, the focus has remained on the utilization of hydrogen bond donors in these systems. Additionally, the majority of the known DESs rely on at least one ionic component. Through the combination of 1,3‐dithiane and 1,2‐diiodo‐3,4,5,6‐tetrafluorobenzene (1,2‐F4DIB), we report the first known DES based on halogen bonding. This mixture remains a liquid, with a eutectic melting temperature of 13.7 °C over a range of 1,3‐dithiane mole fraction (0.35 to 0.75). Additionally, cocrystals of 1,3‐ and 1,4‐dithiane with 1,2‐, 1,3‐, and 1,4‐F4DIB, as well as 1,3,5‐trifluoro‐2,4,6‐triiodobenzene were studied via single‐crystal X‐ray diffraction. These data reveal a wide range of halogen bonding strengths (0.85<RXB<0.99; RXB=normalized halogen bond distance parameter) and geometries about the sulfur atom. By including intermolecular interactions beyond hydrogen bonding, the scope of possible DES systems can be greatly expanded.

Halogen Bonding in Dithiane/Iodofluorobenzene Mixtures: A New Class of Hydrophobic Deep Eutectic Solvents.

While research into deep eutectic solvents (DESs) has expanded over the previous two decades, the focus has remained on the utilization of hydrogen bond donors in these systems. Additionally, the majority of the known DESs rely on at least one ionic component. Through the combination of 1,3-dithiane and 1,2-diiodo-3,4,5,6-tetrafluorobenzene (1,2-F4 DIB), we report the first known DES based on halogen bonding. This mixture remains a liquid, with a eutectic melting temperature of 13.7 °C over a range of 1,3-dithiane mole fraction (0.35 to 0.75). Additionally, cocrystals of 1,3- and 1,4-dithiane with 1,2-, 1,3-, and 1,4-F4 DIB, as well as 1,3,5-trifluoro-2,4,6-triiodobenzene were studied via single-crystal X-ray diffraction. These data reveal a wide range of halogen bonding strengths (0.85<RXB <0.99; RXB =normalized halogen bond distance parameter) and geometries about the sulfur atom. By including intermolecular interactions beyond hydrogen bonding, the scope of possible DES systems can be greatly expanded.

Critical Assessment 40: A search for the eutectic system of high-temperature cast aluminium alloys

A quest for the eutectic system of novel cast aluminium alloys, having high-temperature capabilities, is critically assessed with two potential candidates of Al–Al3Ni and Al–Al11Ce3 examined and compared to the presently used Al–Si base. The conventionally cast Al–Al3Ni and Al–Al11Ce3 eutectics do not exhibit the anticipated advantage over Al–Si in strengthening retention at temperatures up to 500°C. The promising differences between diffusivities of silicon, nickel, and especially cerium in aluminium, and eutectic melting temperatures, accompanied by high coarsening resistance of Al3Ni, Al11Ce3 phases and the eutectic hardness retention are inconsistent with observed similarities in the temperature-related strengthening-reduction of all three eutectics. These findings will help defining the criteria for development of the eutectic system, suitable for future heat-resistant aluminium alloys.

Composition and structure of the diamond/low carbon steel transition zone obtained by contact heating in vacuum at Fe–C eutectic temperature

The study covers the structure, elemental and phase composition of products formed in the contact interaction between diamond and low-carbon steel in vacuum at the Fe–C eutectic melting temperature. Cylindrical tablets made of low carbon steel with a maximum carbon content of 0.1 wt.% and natural diamond crystals in the form of a pyramid (or truncated pyramid) were used as contact pairs. The flat bases of diamond crystals were mounted on the horizontal surface of steel tablets with the load applied to the top of diamond crystals. Contact samples were sintered in a vacuum furnace at a maximum heating temperature of ~1165 °C. After holding at this temperature for 5 minutes, the furnace was turned off and the temperature in its chamber decreased in free cooling mode. Sintered diamond/steel tablet samples were studied by optical and scanning electron microscopy, X-ray diffraction analysis and Raman spectroscopy. It was found that the Fe–C eutectic melt forms in the diamond/steel tablet contact zone, a thin layer of which, when solidified, welds a diamond crystal to the steel tablet under the temperature-time heating mode specified in the experiment. Their bonding strength is such that welded samples without separation can withstand intense cyclic loads during grinding and polishing when making longitudinal sections of samples necessary for metallographic studies. It was shown that the Fe–C eutectic alloy is a gray cast iron with a ferrite-perlite metal base and lamellar graphite inclusions. The microhardness of the solidified Fe–C eutectic was ~1714 MPa. The initial steel tablet with a ferrite-perlite structure was subjected to cementation during sintering in contact with diamond. The most intensive cementation occurred in the ~110 μm thick unmelted upper layer of the steel tablet, which adjoined the Fe–C eutectic during sintering. The microhardness of this layer was ~4945 MPa. As it deepens into the steel tablet there is a gradual transition of the perlite-cementite structure to a perlite one and further to the initial ferrite-perlite microstructure inwards the steel tablet. At the same time, the microhardness changes from ~ 4945 to 1570 MPa.

Diamond and Low Carbon Steel Interaction at Melting Temperature of Fe-C Eutectic

The structure, elemental and phase composition of the products formed during the contact interaction of diamond with low-carbon steel in vacuum at the Fe-C eutectic melting temperature were studied. Cylindrical tablets made of low carbon steel (less than 0.1 % wt. C), and pyramid shaped natural diamond crystals were used as a contact pairs. Diamond crystals were mounted by their flat base on the horizontal surface of steel tablet and a load was applied to the diamond crystals top. Contact samples were sintered in a vacuum furnace at a maximum heating temperature of ~1165 °C. Sintered diamond-steel tablet samples were studied by optical and scanning electron microscopy, X-ray diffraction analysis. It was shown that the initial steel tablet with a ferrite-perlite structure passed cementation during sintering in contact with diamond. The most intensive cementation is undergone by the non-melted upper layer of the steel tablet ~110 μm thick, which adjoined the Fe-C eutectic melt during sintering. The microhardness of this layer was ~4945 MPa. As it deepens into steel tablet a gradual transition of structure from perlite-cementite to perlite and further to the initial ferrite-perlite microstructure is observed. Herewith, the microhardness changes from ~ 4945 to 1570 MPa.

Deliquescence Behavior of Deep Eutectic Solvents

Deep eutectic solvents (DESs) are formed by a hydrogen bond donor and an acceptor. The hydrogen bond interactions between these two components significantly depress the melting temperature of the mixture. DESs have been used as an alternative for organic solvents in various branches of the chemical industry. Many DESs are very hygroscopic and water is known to change the properties of DESs, but there has neven been a systematic study performed on the deliquesence behavior of DESs. Therefore, this study investigated the thermal and deliquescent behavior of four DESs. The DES mixtures were stored in desiccators at different relative humidities (RH) to investigate the critical RH (RH0) for deliquescence. It was found that, due to the formation of a eutonic mixture, the RH0 to induce deliquescence for a given DES mixture was lower compared to the individual components comprising the DES. The results showed that, even though all investigated DESs had eutectic melting temperatures above room temperature, but due to the low RH0, they were able to appear liquid at room temperature under ambient conditions. The eutonic and eutectic compositions were identified at different compositions for the DESs. The results emphasize that great care must be taken to control the process and storage conditions for DESs.

Eutectic Mixing As a Knob for Next-Generation Flow Batteries

Flow batteries can offer scalability, long cycle-life, and power-to-energy tunability, however, they have low energy density. An under-explored “knob” for increasing the energy density of flow batteries is eutectic mixing for the depression of melting points. This knob could enable high energy-density flow batteries by achieving solvent-free electrolytes. We demonstrate the ability of eutectic mixing to decrease melting points in the case of n-component mixtures of benzoquinone derivatives, which are redox-active molecules. Predicting the properties of mixtures of more than two components is not commonly done, but we show that, in this case, a regular solution model has predictive power for finding the eutectic melting temperatures and compositions for mixtures of multiple components.

Mineralogy, fluid inclusions and carbon isotopes of the Kaman iron deposits, Central Anatolia, Turkey: Implication for ore genesis and hydrothermal evolution

The Kaman iron deposits are located in Central Anatolia and are hosted by the Triassic Bolçadağ Marble and Upper Cretaceous Çelebi granitoid. Magnetite mineralization manifests as rhythmic banded and irregular lenses, which can be massive or disseminated within calcic marble and skarn zones. Six main paragenetic stages of skarn formation and ore deposition have been identified: (1) Na-(Ca) alterations composed of plagioclase (An4–31), and actinolite; (2) a prograde stage representing oxidized mineralogy dominated by diopside (Di62–98Joh0–4), grossular–andradite (Grs15–84Alm4–8Sps1–4) and magnetite; (3) a retrograde stage consisting of epidote (Ep51–62Cli38–49), magnetite, calcite, quartz, and less-abundant sulfides and chlorite; (4) a quartz-calcite-pyrite stage containing pyrite, quartz, calcite, and chlorite; and (5, 6) quartz-carbonate and supergene stages characterized by quartz, calcite, hematite, and chalcedony, goethite.Fluid inclusion and carbon isotope studies have shown that the prograde stage formed from moderate–high-salinity (7.1 to >70 wt% NaCl eq.) and high-temperature (339 to >600 °C) fluids. Liquid and vapor-rich inclusions in an early garnet were homogenized in the liquid and vapor phases in a similar temperature range (513 and 529 °C). The δ18O and δ13C of calcites that accompany rhythmic banded magnetite ranged from 22.82 to 23.50‰ and −4.68 to −5.31‰, respectively. The retrograde stage was formed from low–high-salinity (2.9 to 45.4 wt% NaCl eq.) and low–high-temperature (167 to 459 °C) fluids. The δ18O and δ13C of skarn calcites ranged from 4.34 to 15.86‰ and −3.57 to 0.23‰, respectively. The quartz-calcite-pyrite stage was formed from low-salinity (3.1–7.5 wt% NaCl eq.) and temperature (171–392 °C) fluids. The δ18O and δ13C values were −2.38‰ and 2.43‰, respectively. The quartz-carbonate stage formed from low-salinity (3.6 to 5.7 wt% NaCl eq.) and temperature (129 to 169 °C). In all phases, the eutectic and clathrate melting temperatures ranged from −59.5 to −52.2 °C and +4.4 to +12.0 °C, respectively. This indicates that the solutions contain H2O–NaCl–CaCl2–(±MgCl2)–CO2.These fluid inclusion data suggest that fluid boiling occurred under pressures between ~60 and 70 MPa based on hydrostatic consideration during the prograde stage. The main magnetite deposition occurred following boiling, with rising salinity and temperature magmatic–hydrothermal fluids and in the pressure range of ~15 to 50 MPa. Depletion in δ13C was attributed to high-temperature fluid infiltration and indicates an open-system volatilization process. It is suggested that the retrograde stage had developed in two episodes, with the carbofracturing effect triggered by CO2. The carbon isotope data of calcites indicate the mixing of low-temperature metasomatic and meteoric water in later stages. The mineralogy, microthermometry, and carbon isotope results reveal that Kaman iron deposits were developed by a combination of processes such as contact infiltration metasomatism, fluid–rock interaction, cooling, and fluid mixing as a result of decreasing pressure.

Construction of a Room-Temperature Eutectic Binary Phase Diagram by Use of Differential Scanning Calorimetry

A eutectic system is a mixture of two or more substances, displaying a melting temperature lower than its standalone components. The eutectic composition displays the lowest melting temperature of all mixtures. Typically, a eutectic system is used as an example of binary phase diagrams to demonstrate to undergraduate students. Herein, the liquidus and solidus define regions in the phase diagram where the mixture is either a liquid, a solid, or a combination of both. This experiment aims to construct the binary phase diagram of a mixture of menthol (M) and lauric acid (LA) by measuring the thermal properties of a wide range of compositions utilizing differential scanning calorimetry (DSC). The solidus and liquidus are uniquely located below room temperature. The eutectic melting temperature is around 12 °C, while the standalone menthol and lauric acid components melt at 36 and 48 °C, respectively. This allows the visual demonstration of the compositions in all of the defined regions in the binary phase diagram. Furthermore, the theory of cryoscopy is utilized to predict the liquidus of the phase diagram. The comparison with the experimentally determined melting temperatures allows the undergraduate students to reflect on the reliability of the derived equation.