Low Melting Temperature Research Articles

Computational modeling and virtual analysis using a moving heat source to join AZ61A and AA7075 alloys with the application of a titanium alloy interlayer

Laser beam welding (LBW) uses a concentrated laser beam to fuse materials, providing benefits such as a smaller heat-affected zone (HAZ), speed, accuracy, adaptability across multiple materials, and seamless adoption into automation processes. Achieving optimal weld quality with LBW remains difficult due to the need to select the appropriate welding process variables and proper interlayer between dissimilar materials. Due to the high cost and safety risks to operators and equipment in LBW, it is challenging to use the practical experiment. Additionally, welding materials with high thermal conductivity and lower melting temperatures, such as AZ61A and AA7075, is a considerable challenge. Previous research focused on process parameters in laser beam welding of various metals, but not enough consideration has been given to the effect of a titanium interlayer on AA7075 and AZ61A using virtual data. This study aims to fill these gaps by using simulation data to assess the effects of process parameters and the titanium interlayer during LBW of dissimilar materials. A backpropagation neural network with the gradient descent learning rule was used for optimization, and a central composite design was used to predict the optimal process parameter interaction. The result indicates the optimum equivalent strain is obtained at the values of beam radius between 4.5 to 5 mm. The maximum equivalent stress reached during welding speed is between 4 to 4.5 mm/s. The maximum residual stress was obtained at the number of segments of 160. The predicted maximum and average anticipated errors for peak temperature are 0.1655 % and 0.0210 %, while for residual stress it is computed as 0.1766 % and 0.0754 %. The Ti-interlayer in magnesium and aluminum laser welding reduces peak temperatures, allows for uniform energy distribution, minimizes localized heating, and enhances weld quality while lowering residual stress.

Unraveling hydrate stoichiometry in water/alkyl alcohol systems by thermodynamic modeling

The solid–liquid equilibrium (SLE) phase diagram of water/alkyl alcohol systems indicated the formation of several hydrates. However, due to kinetic limitations and significantly low melting temperatures of these hydrates, assessing their stoichiometry remains an unresolved challenge. To this end, we utilized thermodynamic modeling of SLE in four binary water/alkyl alcohol systems: water/methanol, water/ethanol, water/iso-propyl alcohol (IPA), and water/tert-butyl alcohol (TBA), to check the consistency between the measured SLE phase diagram and the postulated hydrate stoichiometry in each system. We found that two possible hydrates could be formed in the water/methanol system: a stable 1:1 hydrate and a metastable 2:1 hydrate. On the other hand, 4:1 and 2:1 hydrates were formed in the water/ethanol system, and the latter was found to be more difficult to crystallize. The SLE phase diagram of the water/IPA system was more complex compared to the other studied systems, and the determination of the exact stoichiometry of the hydrates was challenging. We found that at least three hydrates should form to describe the measured SLE phase diagram. The stoichiometry of the three hydrates formed in the water/IPA system was 5:1, 2:1, and 3:2. In contrast, the stoichiometry of the hydrates formed in the water/TBA was previously confirmed by single-crystal X-ray diffraction, and the SLE phase diagram of the water/TBA was accurately modeled when the formation of 7:1 and 2:1 hydrates was considered. This work contributes to the fundamental knowledge of hydrate science and offers valuable guidance for the development of more efficient methods for hydrate characterization.

Effect of Phosphate-Bridged Monomer on Thermal Oxidative Behavior of Phthalonitrile Thermosets.

Phthalonitrile thermosets are known for their excellent mechanical, physico-chemical, and fire-retardant properties, making them attractive for aerospace and mechanical engineering applications. When producing and applying phthalonitrile-based structural parts, it is essential to consider aspects such as processability and the long-term stability of the material's properties at high temperatures. In our previous studies, we demonstrated that resins containing phosphate-bridged bisphthalonitrile monomers are easily processable due to their low melting temperature and wide processing window. In this study, we investigated the impact of bis(3-(3,4-dicyanophenoxy)phenyl)phenyl phosphate (PPhPN) monomer content on physico-chemical and mechanical properties, thermal stability, and thermal oxidative stability. This research highlights the importance of conducting long-term thermal oxidative aging studies in addition to thermogravimetric analysis to properly assess the stability of thermosets. The findings indicate that adding less than 15% of PPhPN results in the formation of a crystalline phase, which impairs the resin's processability. Conversely, a high PPhPN content reduces the material's thermal oxidative stability. Therefore, based on mechanical and physico-chemical tests after thermal oxidative aging, it can be concluded that a 10-15% concentration of the phosphate-containing monomer enables easy processability of the phthalonitrile resin and provides excellent long-term thermal oxidative stability at temperatures up to 300 °C, while maintaining a flexural strength exceeding 120 MPa and an elasticity modulus of 4.3 GPa.

Influence of the odd‐even effect of dicarboxylic acids as crosslinker on the physicochemical properties of polyvinyl alcohol

AbstractPolyvinyl alcohol (PVA) was crosslinked with a homologous series of four different dicarboxylic acids, HOOC(CH2) n‐2COOH (n = 2 to 5) viz. oxalic acid (OA; C2), malonic acid (MA; C3), succinic acid (SA; C4) and glutaric acid (GA; C5) containing odd and even number of carbon atoms. The characterization and assessment of synthesized crosslinked films were done using ATR‐FTIR, XRD, SEM, AFM, DSC, rheology, percent swelling and sessile drop contact angle. The odd‐even effect of dicarboxylic acids was observed to significantly influence the physicochemical properties of PVA when employed as a crosslinker. PVA films crosslinked using dicarboxylic acids containing an even number of carbon atoms, displayed translucency, roughness, and an irregular matrix. In contrast, films incorporating an odd number of carbon atoms were transparent, homogenous, and densely packed. Furthermore, films containing even acids exhibited relatively lower crystallinity, lower melting temperature (Tm) and displayed an unexpected irregular trend in swelling as crosslinker concentration increased compared to films containing dicarboxylic acids with an odd number of carbon atoms which exhibits a consistent swelling with increasing crosslinker concentration. These results are attributed to the difference in the solubility and crystal structures of the odd‐even series of dicarboxylic acids.

Hypoeutectic Liquid Metal Printing of 2D Indium Gallium Oxide Transistors.

2D native surface oxides formed on low melting temperature metals such as indium and gallium offer unique opportunities for fabricating high-performance flexible electronics and optoelectronics based on a new class of liquid metal printing (LMP). An inherent property of these Cabrera-Mott 2D oxides is their suboxide nature (e.g., In2O3-x), which leads high mobility LMP semiconductors to exhibit high electron concentrations (ne >1019cm-3) limiting electrostatic control. Binary alloying of the molten precursor can produce doped, ternary metal oxides such as In-X-O with enhanced electronic performance and greater bias-stress stability, though this approach demands a deeper understanding of the native oxides of alloys. This work presents an approach for hypoeutectic rapid LMP of crystalline InGaOx (IGO) at ultralow process temperatures (180°C) beyond the state of the art to fabricate transistors with 10X steeper subthreshold slope and high mobility (≈18cm2Vs-1). Detailed characterization of IGO crystallinity, composition, and morphology, as well as measurements of its electronic density of states (DOS), show the impact of Ga-doping and reveal the limits of doping induced amorphization from hypoeutectic precursors. The ultralow process temperatures and compatibility with high-k Al2O3 dielectrics shown here indicate potential for 2D IGO to drive low-power flexible transparent electronics.

Thermal and heat-sealing properties of polyvinyl alcohol/cellulose nanocrystals-based nanocomposites for food packaging

Food packaging materials require advanced properties (UV barrier and antioxidant/antimicrobial) to extend the shelf-life of packaged products. Recently, we have developed biodegradable nanocomposites by incorporating cellulose nanocrystals (CNCs) and active agents (titanium dioxide nanoparticles and apple peel extract) into polyvinyl alcohol (PVA). These nanocomposites exhibited advanced properties and many demonstrable advantages in food packaging. Herein, the thermal stability, melting behaviors, and heat-sealing properties of these nanocomposites are investigated to demonstrate their potential production at the industrial level and practical use. The results showed that the PVA/CNC-based nanocomposites exhibited thermoplastic properties and had sufficient heat-sealability. The PVA/CNC-based nanocomposites presented lower melting temperatures (217.7–224 °C) than pure PVA (226 °C). Furthermore, their seal strengths (15.1–1238.1 N/m) are similar to those of petroleum-based food packaging polymers (polypropylene: 300–1100 N/m, low-density polyethylene: 677.7 N/m) and can be controlled by adjusting the sealing temperature, which is useful for various food packaging applications.

Effects of TiC nanoparticle addition on microstructures and mechanical properties of Sn-58Bi solder joints

The Sn58Bi solder has gained significant attention in the electronic packaging industry owing to its low melting temperature and excellent mechanical properties. However, the brittleness of Sn58Bi solder presents challenges in practical applications. This study investigates the effect of adding titanium carbide (TiC) nanoparticles on the mechanical properties of Sn58Bi solder joints. The study examines the melting behavior, spreadability, microstructure, and mechanical properties of Sn58Bi-xTiC (x = 0, 0.05, 0.1, 0.2 wt%) composite solders. The results indicate that adding TiC nanoparticles has merely a minor effect on the melting point of the Sn58Bi solder. However, the presence of TiC nanoparticles refined the solder’s microstructure, reduced the thickness of the intermetallic compounds, and enhanced the spreadability and mechanical properties. The Sn58Bi-0.1TiC composite solder exhibits the most favorable properties, including a 28.6 % increase in fracture energy compared with that of Sn58Bi solder. Consequently, incorporating TiC nanoparticles enhances the performance of the Sn58Bi solder by improving its spreadability and reducing its brittleness. These results hold great potential for advancing the development of lead-free solders with improved reliability and performance in electronic applications. The findings of this study could pave the way for the practical and widespread use of Sn58Bi-xTiC composite solders, offering a viable alternative to lead-containing solders while maintaining excellent mechanical characteristics.

Reliability Risk Mitigation in Advanced Packages by Aging-Induced Precipitation of Bi in Water-Quenched Sn-Ag-Cu-Bi Solder.

Bi-doped Sn-Ag-Cu (SAC) microelectronic solder is gaining attention for its utility as a material for solder joints that connect substrates to printed circuit boards (PCB) in future advanced packages, as Bi-doped SAC is reported to have a lower melting temperature, higher strength, higher wettability on conducting pads, and lower intermetallic compound (IMC) formation at the solder-pad interface. As solder joints are subjected to aging during their service life, an investigation of aging-induced changes in the microstructure and mechanical properties of the solder alloy is needed before its wider acceptance in advanced packages. This study focuses on the effects of 1 to 3 wt.% Bi doping in an Sn-3.0Ag-0.5Cu (SAC305) solder alloy on aging-induced changes in hardness and creep resistance for samples prepared by high cooling rates (>5 °C/s). The specimens were aged at ambient and elevated temperatures for up to 90 days and subjected to quasistatic nanoindentation to determine hardness and nanoscale dynamic nanoindentation to determine creep behavior. The microstructural evolution was investigated with a scanning electron microscope in tandem with energy-dispersive spectroscopy to correlate with aging-induced property changes. The hardness and creep strength of the samples were found to increase as the Bi content increased. Moreover, the hardness and creep strength of the 0-1 wt.% Bi-doped SAC305 was significantly reduced with aging, while that of the 2-3 wt.% Bi-doped SAC305 increased with aging. The changes in these properties with aging were correlated to the interplay of multiple hardening and softening mechanisms. In particular, for 2-3 wt.% Bi, the enhanced performance was attributed to the potential formation of additional Ag3Sn IMCs with aging due to non-equilibrium solidification and the more uniform distribution of Bi precipitates. The observations that 2-3 wt.% Bi enhances the hardness and creep strength of the SAC305 alloy with isothermal aging to mitigate reliability risks is relevant for solder samples prepared using high cooling rates.

Equilibrium model approach to predict local chemical changes in recovery boiler deposits

A step-by-step equilibrium model approach was developed to estimate and describe the enrichment of K and Cl within recovery boiler deposits. The model predicts free melt movement towards colder temperatures within deposits. Due to a temperature gradient, the melt amount and composition differ across the deposit. The melt movement affects the local composition, which leads to changes in the local phase composition. The model predicts how the deposit profile changes due to melt migration into pores within the deposits. Changes in the deposit composition profile also affect the melting behavior locally, resulting in lower local melting temperatures, which can be detrimental to heat exchanger materials. The modeling results were compared to earlier published laboratory and full-scale boiler measurements, and there is a good agreement between the results. The model predicts a local decrease in the first melting temperature of recovery boiler deposits by ∼30 °C. These findings closely align with experimental results, shedding light on the intricate mechanisms of melt percolation and intra-deposit aging processes. The proposed step-by-step model offers a means to achieve more accurate estimations of locally prevalent first melting temperatures in recovery boiler deposits.

Molecular origin of the plasticizing effect difference of glycerol with other polyols on plasticizing polyvinyl alcohol (PVA) as elucidated by solid-state NMR

Glycerol has been proved to be an effective plasticizer for polyvinyl alcohol (PVA), which can significantly increase PVA’s processability and ductility, whose molecular origin remains unclear. In current study, the physical structure and chain dynamics of polyol plasticized PVA were studied in detail, including ethylene glycol, glycerol, erythritol, xylitol, and sorbitol under the same addition level. The glycerol plasticized PVA exhibits the most significant reduction in Young’s modulus, enhanced superior toughness, and the lowest melting temperature (195 °C) as compared with other polyols. The molecular mechanism was elucidated through comprehensive analysis, with a particular focus on solid state NMR (SS NMR) results. The physical structure was first elucidated by the Small Angle X-ray Scattering (SAXS) and Wide Angle X-ray Scattering (WAXS). The crystallinity of the glycerol plasticized PVA was the lowest 29 % by WAXS and the thickness of the amorphous layer was the largest 7.76 nm by SAXS among different plasticized PVA films. This suggests the significant influence of glycerol on structure change of PVA. The molecular dynamics information was further accessed by Low Field Nuclear Magnetic Resonance (LF NMR), where two key features are obtained: i) Different dynamics dimensionality. The 1H spin diffusion NMR was used to check the dimensionality from the aspect of chain dynamics. Compared with other plasticizers, LF NMR result shows that glycerol plasticized PVA has a two-dimensional (2D) structure; ii) Chain dynamics heterogeneity in the interphase. With respect to the chain dynamics heterogeneity in the interphase, the glycerol plasticized PVA shows the most heterogeneous dynamics, with the lowest ratio of the rigid amorphous fraction (RAF) of 0.507 in the interphase. Current study provides a versatile analytical strategy to quantify the plasticizing effect.

Flexible Positive Temperature Coefficient Composites (PVAc/EVA/GP-CNF) with Room Temperature Curie Point.

Polymeric positive temperature coefficient (PTC) materials with low switching temperature points are crucial for numerous electronic devices, which typically function within the room temperature range (0-40 °C). Ideal polymeric PTC materials for flexible electronic thermal control should possess a room-temperature switching temperature, low room-temperature resistivity, exceptional mechanical flexibility, and adaptive thermal control properties. In this study, a novel PTC material with a room-temperature switching temperature and superb mechanical properties has been designed. A blend of a semi-crystalline polymer EVA with a low melting temperature (Tm) and an amorphous polymer (PVAc) with a low glass transition temperature (Tg) was prepared. Low-cost graphite was chosen as the conductive filler, while CNF was incorporated as a hybrid filler to enhance the material's heating stability. PVAc0.4/EVA0.6/GP-3wt.% CNF exhibited the lowest room temperature resistivity, and its PTC strength (1.1) was comparable to that without CNF addition, with a Curie temperature of 29.4 °C. Room temperature Joule heating tests revealed that PVAc0.4/EVA0.6/GP-3wt.% CNF achieved an equilibrium temperature of approximately 42 °C at 25 V, with a heating power of 3.04 W and a power density of 3.04 W/cm2. The Young's modulus of PVAc0.4/EVA0.6/GP-3wt.% CNF was 9.24 MPa, and the toughness value was 1.68 MJ/m3, indicating that the elasticity and toughness of the composites were enhanced after mixing the fillers, and the mechanical properties of the composites were improved by blending graphite with CNF.

Experimental Investigation of Processing Temperature Effect on Adhesive Bond Strength Between Engineering Thermoplastics in the Plastic Injection Molding Process

Abstract Multicomponent injection molding industry is experiencing a growth due to its ability to reduce production costs and streamline processes. However, compared to single injection, multicomponent injection molding introduces interface regions where multiple engineering polymers meet. Consequently, it is essential to comprehend and enhance the adhesive bonding strength properties of these polymers. This study investigates the adhesive bond strength of polymer–polymer multimaterial molding using two-shot bi-injection and overmolding techniques. The research also emphasizes the influence of injection molding process parameters of mold temperature and melt temperature on the adhesive bond strength of polycarbonate (PC), polycarbonate–acrylonitrile butadiene styrene (PC–ABS), acrylonitrile butadiene styrene (ABS), and styrene ethylene butadiene styrene (SEBS). Tensile strength results revealed that the bi-injection method yields the highest interface strength, approximately 10 MPa lower than the reference value for single-material hard–hard plastics. Results from overmolded samples for both injection sequences are presented, indicating that material with low melting temperature was found to be the first injected part for better adhesion strength. Empirical equations for estimating adhesion strength were derived as a function of interface temperature obtained from CAE numerical simulations and polymer glass transition temperatures. The proposed equation achieved R2 values greater than 0.96. This empirically derived equation will serve as a guide for multi-injection manufacturing processes.

Cold energy storage enhancement and phase transition temperature regulation

The objective of this study is to prepare a highly adjustable ester phase change material (PCM) and further optimize its cold storage properties using a simple and controllable physical method. Initially, lauric acid (LA) and polyethylene glycol 200 (PEG 200) are selected as raw materials, and a non-toxic and environmentally friendly polyethylene glycol laurate (PLE) with a tiny supercooling is prepared under the condition of acid-alcohol molar ratio of 1:3. To further regulate the cold storage property of PLE, a series of PCMs with different melting temperatures are successfully prepared using PLE blended with ethanol (EA). Among them, the lowest melting temperature in the study reaches −15.2 °C, which is about 94.6 % lower compared to −7.81 °C for PLE, and the highest latent heat of melting is 81.56 J/g. It is also observed that the supercooling of a range of samples is also optimized compared to the PLE, with a maximum reduction of 27.1 %. Additionally, the prepared samples not only exhibit excellent stability but also demonstrate outstanding application potential in temperature control and preservation experiments. This innovative achievement provides a richer selection of PCMs for the cold storage field. More crucially, this is the first report utilizing EA to regulate the temperature range of ester-based PCMs. This method is simple, easy to operate, and highly reproducible. It paves the way for the refinement, diversification, and customization of refrigeration technology.

Pressure effect on the structural, electronic, mechanical, optical and thermal properties of Ga2TiX6 (X = Cl, Br): A DFT simulation

The pressure effect on the physical properties of Ga2TiX6(X = Cl, Br) has been carried out through density function theory (DFT) accomplished via CASTEP guidelines. At ambient condition the structural aspects of Ga2TiX6(X = Cl, Br) show well accord with the previous theoretical data. A dramatically decrease of lattice constants, cell volumes and bond length with pressure is perceived. The negative enthalpy energy ensured the chemical formation of Ga2TiX6(X = Cl, Br). The positive stiffness constants (Cij) ensure the mechanical stability of Ga2TiX6(X = Cl, Br) at ambient and hydrostatic pressure. Moreover, the fundamental polycrystalline factors of phases Ga2TiX6(X = Cl, Br) such as bulk, shear and Young’s moduli, Poisson’s and Pugh’s fraction, machinability index as well as hardness of these materials have been calculated and discussed at ambient and hydrostatic pressure. Having very low values of bulk modulus (<100 GPa) they can be considered as soft materials. The increase of machinable index with pressure ensure the high lubricating properties, low friction, and high plastic strain of Ga2TiX6(X = Cl, Br) and also ensure their possible industrial applications. Band structure analysis ensure the semiconducting nature of Ga2TiX6(X = Cl, Br) at ambient condition but the semiconducting nature shift to metallic manner at 55 GPa and 65 Gpa respectively. The decrease of total density of states is observed at high pressure. The creation of new bond at high pressure is also observed in materials Ga2TiX6(X = Cl, Br). The investigated optical features ensured that the studied phases can be used in UV photodiodes, and UV light emitters since they revel intense peaks at UV region. Very low Debye temperature, melting temperature and thermal conductivity are observed at ambient condition which ensures that the compounds Ga2TiX6(X = Cl, Br) can be used as thermal barrier coating materials (TBC).

Advancing sustainable shape memory polymers through 4D printing of polylactic acid-polybutylene adipate terephthalate blends

One of the major challenges in 4D printed Shape Memory Polymers (SMPs) is their slow response to thermal stimuli. Synthetic carbon fillers have been introduced to address this issue; however, their use comes with environmental concerns. On the other hand, Polylactic Acid (PLA) is commonly used for 3D/4D printing of SMPs, but it requires softening to achieve large deformations. This research paper introduces a sustainable solution through blending PLA with Polybutylene Adipate Terephthalate (PBAT) that not only addresses these challenges but also possesses environmental eco-friendliness due to PBAT’s high biodegradability rate. PBAT with weight percentages of 15 %, 30 %, and 45 % is utilized to soften PLA, and their composites are successfully 4D printed. Mechanical properties, shape memory effects, morphology, and thermal behaviors are comprehensively investigated. The results show that blending PLA with 45 % PBAT weight results in excellent features such as 220 % elongation and 93 % shape recovery in just a few seconds. The other two PLA-PBAT blends achieve complete shape recovery in less than 8 s. The PLA-PBAT contains 15 % PBAT, in addition to high strength (40 MPa), has 17 % elongation. This, coupled with the low melting temperature of PBAT, drives the high shape recovery rate. Scanning electron microscopy images finally confirm the high printability of all three blends, with the PLA-PBAT composite containing 30 % PBAT exhibiting the best quality in layer interfaces and the least porosity.

Effect of methane flow in inverse diffusion flame and surface morphology on synthesis of copper–carbon nanotubes composite

ABSTRACT In an inverse diffusion flame of fuel-rich methane–air mixture, a distinct separation between a yellow flame situated atop a high-temperature blue flame structure enabled the growth of carbon nanotubes on relatively low melting temperature copper substrates within a carbon-rich precursor environment. However, high-affinity passivation layers formation on copper prevented the diffusion of carbon precursors, rendering the growth of carbon nanotubes on copper challenging. Removal of passivation layers via sulphuric acid treatment facilitates the synthesis of carbon nanotubes within the flame. Nevertheless, the impact of sulphuric acid treatment on the surface morphology of copper, and its influence on the growth of carbon nanotubes in the presence of methane–air mixtures, remains relatively unexplored. This research investigates the effects of sulphuric acid treatment and methane–air mixtures towards the growth of carbon nanotubes on copper substrates. Application of sulphuric acid treatment yields a surface characterised by high surface area-to-volume nano-hills morphology, which enhances the adsorption of carbon atoms and leads to the growth of carbon nanotubes with lifted copper nanoparticles. The optimal growth of carbon nanotubes occurs at a specific methane flow rate, where the supply of carbon precursors aligns with the diffusion of carbon atoms and growth rate of carbon nanotubes.

Li-mineralized pegmatite of anatectic origin: Constraints from Li[sbnd]Hf isotopes and geochemical modeling

Pegmatites are important reservoirs of lithium resources. There is an ongoing debate as to whether Li-mineralized pegmatites were generated from evolved granitic systems via extreme differentiation or by direct melting of metasedimentary rocks. The Chinese Altay is one of the largest pegmatite provinces in the world, and includes many rare-metal pegmatites (e.g., Koktokay, Kelumute, Kaluan and Azubai). However, they display significant differences in formation ages and isotopic compositions compared with the neighbouring or potential parental granites. In this contribution, we present a case study of the Kaluan Li ore deposit in the Chinese Altay, elucidating the origins of pegmatites and related Li mineralization. The Kaluan Li-mineralized pegmatites are characterized by high SiO2, K2O, Na2O, Li, Cs, Ta, and Rb contents; low Fe2O3T, MgO, Ba, and Sr contents; and peraluminous signatures. They have homogeneous HfLi isotopic compositions (εHf (t) = −0.6 to +2.5; δ7Li = +1.6 to +5.8‰) that are within the range of HfLi isotopic compositions of the Kulumuti Group schists (εHf (t) = −2.8 to +7.5; δ7Li = −8.6 to +10.8‰). In addition, the chemical compositions of the melt derived from the partial melting of the Kulumuti Group by phase equilibrium modeling are compatible with our analyses of the Kaluan Li-mineralized pegmatites. These similarities suggest that the Kaluan Li-mineralized pegmatites were derived from the partial melting of the Kulumuti Group schists at depths during the Triassic, in a post-orogenic and extensional setting. The generation of these pegmatites was mostly controlled by biotite dehydration melting at relatively high temperatures, rather than by the low-temperature melting of muscovite. Trace elements modeling results show that approximately 33–36% partial melting of the average Kulumuti Group schist may produce melts with maximum Li concentrations ranging from 664 to 751 ppm. Subsequently, a high degree of fractionation exceeding 85%, was required for the Li concentration of the residual melt to reach concentrations suitable for crystallization into albite-spodumene pegmatites. Based on our research, an anatectic origin model may have general applicability in explaining the genesis and mineralization of rare-metal pegmatites in the Chinese Altay.

Reversible Glass‐Crystal Transition in a New Type of 2D Metal Halide Perovskites

AbstractCrystalline metal halide perovskites (MHPs) have ushered in remarkable advancements across diverse fields, including materials, electronics, and photonics. While the advantages of crystallinity are well‐established, the ability to transition to a glassy state with unique properties presents unprecedented opportunities to expand the structure‐property relationship and broaden the application scope for 2D MHPs. Up until now, the exploration of amorphous analogs for MHPs is confined to high‐pressure conditions, limiting in‐depth studies and practical applications. In this context, a new type of 2D MHPs is synthesized by incorporating halogen substituted organic cations, resulting in a remarkable combination of low melting temperature and inhibited crystallization. This new type of 2D MHPs can be effectively melt‐quenched into a glassy state except for (DMIEA)3Pb2I7 (DMIEA = N, N‐dimethyl iodoethylammonium) counterpart. Analysis of the crystallization activation energy for (DMIPA)4Pb3I10 (DMIPA = N, N‐dimethyl iodopropylammonium) reveals a low crystallization activation energy of 60.7 ± 4.0 kJ mol−1, which indicates a fast glass‐crystal transition. The type of atypical 2D MHP showcases facile and reversible switching between glassy and crystalline states and opens up novel possibilities for applications, such as nonvolatile memory, optical communication, and neuromorphic computing.

Tuning metastable austenite in a phase-transforming ceramic via matrix constraint

Martensitic phase-transforming ceramics can undergo reversible phase transformations under thermo-mechanical stimuli, yet brittle in their monolithic, polycrystalline form. Incorporating these ceramics into matrices thereby metastabilizing austenite gives rise to a significant toughening effect by triggering martensitic transformation. However, it remains a challenge to stabilize the austenite if the matrix is a light metal, because of its low strength, low melting temperature and high-chemical reactivity. In this study, we constructed a phase-transforming ceramic-metal (zirconia-aluminum) composite with tunable metastable austenite fractions via matrix constraint. Systematic experiments combined with thermodynamic and kinetic models uncover the effect of the matrix constraint and doping concentration on austenitization. By varying the processing parameters, we realized extensive tunability in metastable austenite content (0–100 wt.%) under different cerium doping concentrations (6–12 mol.%) in a wide range of processing temperatures (350–550°C). Our findings reveal the underlying mechanisms for promoting, stabilizing and fine-manipulating austenitization in martensitic phase-transforming ceramics under geometrical constraint, and may lay out the foundation for more extensive studies and applications of these phase-transforming ceramic-based composites.

Novel milk fat fractions for health and functionality obtained by short-path distillation

Medium-chain fatty acids (MCFA) are associated with various health benefits, such as enhanced insulin sensitivity and reduced appetite. The study explored the potential of combining dry or solvent fractionation with short-path distillation (SPD) to obtain milk fat (MF) fractions enriched in MCFA. By using only SPD, a 2-fold increase in MCFA and an 18-fold increase in α-tocopherol in distillates was obtained compared to native MF. The distillate has a lower melting temperature than does MF. Pre-fractionation processes before SPD did not lead to an additional increase in MCFA. The study demonstrates the potential of SPD to produce MF fraction (distillate) with significant enrichment in MCFA, differed thermal behavior, and increased α-tocopherol content while keeping the FA composition and thermal properties of the remaining fraction (retentate) similar to MF as only 10% of the milk fat have been removed.