Variation Of Phase Composition Research Articles

GMP-Compliant Automated Radiolabeling and Quality Controls of [68Ga]Ga-FAPI-46 for Fibroblast Activation Protein-Targeted PET Imaging in Clinical Settings.

In nuclear medicine, molecular imaging of the tumor microenvironment using radiopharmaceuticals (RPs) targeting cancer-associated fibroblasts is gaining significant interest. Among these RPs, [68Ga]Ga-FAPI-46 for positron emission tomography (PET) imaging is frequently used in clinical research protocols. To ensure that the production of this RP complies with good manufacturing practices, process automation is widely adopted. In this context, an automated method for preparing [68Ga]Ga-FAPI-46 was designed using a GAIA® synthesizer. Additionally, a HPLC method was developed and validated to determine the radiochemical purity (RCP) of [68Ga]Ga-FAPI-46 and ensure product quality. The validated HPLC method showed excellent repeatability, with coefficients of variation (%CV) for RCP and retention time (tR) below 0.03 and 0.16%, respectively, across 10 measurements. The radiochemical identification of [68Ga]Ga-FAPI-46 showed comparable tr values to [natGa]Ga-FAPI-46 (6.65 and 6.59 min, respectively). The limits of detection (LOD) and quantification (LOQ) were 79 and 42 kBq/mL, respectively, with a linear detector response between 62.9 and 0.08 MBq/mL (R2 = 0.9999). The method proved robust, tolerating minor variations in mobile phase flow rate and composition. This validated radio-HPLC method can be used routinely for the quality control of [68Ga]Ga-FAPI-46. Finally, three RP validation batches were produced using the automated method described and subjected to multiple quality controls. All three synthesis products met the expected specifications, notably regarding appearance, chemical and isotope identification, pH, sterility, stability, and radionuclidic and radiochemical purity.

Predicting CO2 and H2 Solubility in Pure Water and Various Aqueous Systems: Implication for CO2–EOR, Carbon Capture and Sequestration, Natural Hydrogen Production and Underground Hydrogen Storage

The growing energy demand and the need for climate mitigation strategies have spurred interest in the application of CO2–enhanced oil recovery (CO2–EOR) and carbon capture, utilization, and storage (CCUS). Furthermore, natural hydrogen (H2) production and underground hydrogen storage (UHS) in geological media have emerged as promising technologies for cleaner energy and achieving net–zero emissions. However, selecting a suitable geological storage medium is complex, as it depends on the physicochemical and petrophysical characteristics of the host rock. Solubility is a key factor affecting the above–mentioned processes, and it is critical to understand phase distribution and estimating trapping capacities. This paper conducts a succinct review of predictive techniques and present novel simple and non–iterative predictive models for swift and reliable prediction of solubility behaviors in CO2–brine and H2–brine systems under varying conditions of pressure, temperature, and salinity (T–P–m salts), which are crucial for many geological and energy–related applications. The proposed models predict CO2 solubility in CO2 + H2O and CO2 + brine systems containing mixed salts and various single salt systems (Na+, K+, Ca2+, Mg2+, Cl−, SO42−) under typical geological conditions (273.15–523.15 K, 0–71 MPa), as well as H2 solubility in H2 + H2O and H2 + brine systems containing NaCl (273.15–630 K, 0–101 MPa). The proposed models are validated against experimental data, with average absolute errors for CO2 solubility in pure water and brine ranging between 8.19 and 8.80% and for H2 solubility in pure water and brine between 4.03 and 9.91%, respectively. These results demonstrate that the models can accurately predict solubility over a wide range of conditions while remaining computationally efficient compared to traditional models. Importantly, the proposed models can reproduce abrupt variations in phase composition during phase transitions and account for the influence of different ions on CO2 solubility. The solubility models accurately capture the salting–out (SO) characteristics of CO2 and H2 gas in various types of salt systems which are consistent with previous studies. The simplified solubility models for CO2 and H2 presented in this study offer significant advantages over conventional approaches, including computational efficiency and accuracy across a wide range of geological conditions. The explicit, derivative–continuous nature of these models eliminates the need for iterative algorithms, making them suitable for integration into large–scale multiphase flow simulations. This work contributes to the field by offering reliable tools for modeling solubility in various subsurface energy and environmental–related applications, facilitating their application in energy transition strategies aimed at reducing carbon emissions.

A fully coupled multiscale phase-change model at the porous interface for transpiration cooling: coupling dynamics pore-scale networks to continuum-scale free flow

Being a promising method for thermal protection system, transpiration cooling has received wide interest recently. Numerical simulation for transpiration cooling, however, has been limited due to the mis-matching between the pore-scale two-phase flow and external high-temperature aerothermodynamic environment, which induced by conventional decoupled or iterative one-way coupled simplification methods. In this work, a fully coupled continuum-scale and pore-scale model is established for transient transpiration cooling at the interface between boundary layer flow and porous medium through coupling Computational Fluid Dynamics (CFD) and Pore-Network Model (PNM), termed as the multiscale CFD-PNM coupled method. The coupled method allows to capture detailed displacement and phase change of two-phase flow at pore-scale, revealing the strong interaction of the water vapor with the external free flow within a high temperature boundary layer. After successfully validating the new coupled model by comparing with the Two-Phase Mixture Model (TPMM) solution, a number of cases mimicking the cooling at the interface of typical blunt bodies are simulated. The results show that the multiscale CFD-PNM coupled method can not only provide the thermal protection effect prediction, but also reveal many critical features that beyond the reach of continuum-scale studies. Some pore-scale phenomena that are important to the overall transpiration cooling effects are revealed, including transient phase change and composition variation of water vapor, imbibition and drainage of two-phase flow related to pore-scale capillary thresholds and applied boundary pressures, as well as the two-way mass transfer at the interface, such as the invasion of external hot air.

Improved gyromagnetic properties of LiZnTi ferrites co-fired with Bi2O3-La2O3 additives at low temperature

In this work, low temperature-sintered Li0.43Zn0.27Ti0.13Fe2.17O4 ferrites mixed with x wt.% (x = 0.00–0.30 wt%) of La2O3 and 1.5 wt% of Bi2O3 were successfully prepared by the solid-state reaction method. The variations in phase composition, microstructure, and gyromagnetic properties of the as-prepared samples were studied in detail. XRD patterns and refinement results show that La2O3 didn't affect the formation of the spinel phase, but a small amount of La3+ might enter into the lattice structure. The micro-morphological analysis and grain size statistics demonstrate that the addition of La2O3 significantly suppressed the grain growth, and the average grain size decreased from 2.19 μm (x = 0.00 wt%) to 1.14 μm (x = 0.15 wt%). The uniformity of the grain size distribution was improved, and the degree of densification was significantly increased. Meanwhile, the saturation magnetization (4πMs) increased from 3921 Gs to 3989 Gs, the coercivity (Hc) decreased from 457.5 A/m to 312.5 A/m, and the ferromagnetic resonance linewidth (ΔH) decreased from 328.5 Oe to 220.7 Oe. Our study indicates that the Bi2O3-La2O3 mixture is an effective sintering additive for low-temperature sintering of LiZnTi ferrite ceramics, which will play an important role in the development of low-temperature co-fired ferrites.

Effect of Phase Composition Variation of Oxy–Nitride Composite Ceramics on Heat Resistance and Preservation of Strength Parameters

The aim of this study is to determine the effect of changes in the phase composition of Al2O3–Si3N4 ceramics that were obtained using the method of mechanochemical solid-phase grinding on their resistance to the process of long-term thermal exposure, accompanied by the processes of oxidation and softening. The relevance of this research consists of determining the influence of the phase composition of ceramics on the change in their strength and thermophysical parameters, on the basis of which, we can draw a conclusion about the optimal composition of composite ceramics that have great prospects in the field of fire-resistant, heat-resistant, or radiation-resistant structural materials. During this study, the dynamics of the changes in the phase transformations of the xAl2O3–(1−x)Si3N4 ceramics, with variations in the ratio of the components, initiated by the thermal annealing of the samples, was established. According to the assessment of the phase transformations with variations in the ratio of the components, it was found that thermal annealing in an air environment at an Al2O3 concentration in the order of 0.3–0.5 M leads to the formation of an orthorhombic Al2(SiO4)O phase and an elevation in its contribution at concentrations above 0.5 M, which causes a rise in the thermophysical parameters and resistance to high-temperature degradation. During the heat resistance tests, it was found that the formation of the composite ceramics with the Si3N4(SiO2)/Al2(SiO4)O/Al2O3 phase composition results in an increase in the stability of their strength properties when exposed to thermally induced oxidation, which has a negative impact on their resistance to softening and a decrease in hardness. Moreover, the presence of the Al2(SiO4)O phase in the composition of the ceramics causes a slowdown in the processes of thermal oxidation of the Si3N4 phase under prolonged temperature exposure, alongside an increase in the degradation resistance of strength properties by more than 4–7 times, in comparison with the softening data established for single-component ceramics.

Enabling Invar to Ti6Al4V transitions through copper in functionally graded laser powder bed fused components

This study examines the microstructural evolution, elemental distribution, phase composition, and hardness variations in multi-material samples fabricated using Laser Powder Bed Fusion (LPBF) with Invar and Ti6Al4V with compositional gradients mediated by copper. A range of compositional transitions from Invar to Ti6Al4V with different copper fractions are reported. Defects such as gas and keyhole pores were detected in well-deep keyhole mode areas, while lack of fusion defects were observed in samples with pure Cu interlayers due to poor wettability and processing parameter variations. Crack formation between interlayer gradient zones and Invar regions was linked to FeNi and CuNi intermetallic phases. Intermetallic compounds (e.g., FeNi, CuNi, TiFe, TiNi) significantly influenced the microstructure and mechanical performance. Vickers hardness testing shows varying hardness across different builds, with the highest hardness being observed in the gradient zone enabled by pure copper (approximately 620 HV). This study also underscores the need for tailored component design linking build processing parameters and compositional transitions in multi-material LPBF to achieve desired properties and component structural behaviour.

Engineering of LiTaO3 Nanoparticles by Flame Spray Pyrolysis: Understanding In Situ Li-Incorporation into the Ta2O5 Lattice.

Lithium tantalate (LiTaO3) perovskite finds wide use in pyroelectric detectors, optical waveguides and piezoelectric transducers, stemming from its good mechanical and chemical stability and optical transparency. Herein, we present a method for synthesis of LiTaO3 nanoparticles using a scalable Flame Spray Pyrolysis (FSP) technology, that allows the formation of LiTaO3 nanomaterials in a single step. Raman, XRD and TEM studies allow for comprehension of the formation mechanism of the LiTaO3 nanophases, with particular emphasis on the penetration of Li atoms into the Ta-oxide lattice. We show that, control of the High-Temperature Particle Residence Time (HTPRT) in the FSP flame, is the key-parameter that allows successful penetration of the -otherwise amorphous- Li phase into the Ta2O5 nanophase. In this way, via control of the HTPRT in the FSP process, we synthesized a series of nanostructured LiTaO3 particles of varying phase composition from {amorphous Li/Ta2O5/LiTaO3} to {pure LiTaO3, 15-25 nm}. Finally, the photophysical activity of the FSP-made LiTaO3 was validated for photocatalytic H2 production from H2O. These data are discussed in conjunction with the role of the phase composition of the LiTaO3 nanoparticles. More generally, the present work allows a better understanding of the mechanism of ABO3 perovskite formation that requires the incorporation of two cations, A and B, into the nanolattice.

Investigations on porous silicon nitride ceramics prepared by the gel-casting method

Abstract Due to their special structure and many excellent properties, porous Si3N4 ceramics have a wide range of potential applications as a new structural and functional integrated material. In the present study, porous Si3N4 ceramics with excellent bending properties and satisfactory porosity were prepared by the gel-casting method. The variations in porosity, bending strength, fracture morphology and phase composition of the porous Si3N4 ceramics with different weight fractions of La2O3–MgO sintering additive were investigated. The results showed that the density of porous Si3N4 ceramics increased linearly with the increase of sintering additive content. When the content of sintering additive increased from 2.5 wt.% to 10 wt.%, the porosity of porous ceramics decreased from 30 % to 10 %. With the increase of sintering additive content, the bending strength of the samples first increased and then decreased. When the sintering additive content was 5.0 wt.%, the average bending strength of the samples reached a maximum of 240.88 MPa, and scanning electron microscopy and X-ray diffractometry results showed that β-Si3N4 particles with well-developed pores and a maximum aspect ratio of 5.8 were formed in the porous silicon nitride ceramics. This study provides a reference for the preparation of porous Si3N4 ceramics with good bending properties and porosity.

Transmission Electron Microscopic and X-ray Diffraction Based Study of Crystallographic Bibliography Demonstrated on Silver, Copper and Titanium Nanocrystals: State of the Art Statical Review

This statistical review compares the crystallographic structures of functional nanocrystals composed of silver (Ag), copper (Cu) and titanium (Ti) using transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses. TEM provides high-resolution imaging to directly visualize individual nanoparticles' size, internal shape and crystallinity. Statistical analysis quantifies variations in lattice parameters, crystal structure, size distributions, phase compositions, lattice strains, preferred orientation and lattice volume of these three crystalline nanomaterials. The review highlights the complementary roles of TEM and XRD in comprehensive Ag, Cu and Ti nanocrystalline materials characterization. The crystallographic functional parameters of Ag were 2θ= 38.1° (111), 44.3° (200) and 64.4° (220); for Cu crystal 43.3° (111), 50.4° (200), 74.1° (220), 89.9° (311) and 95.1° (222) and 35.1° (100), 38.4° (002), 40.2° (101), 53.0° (102), 63.0° (103), 70.7° (110), 76.2° (112), 82.3° (201) demonstrated for Ti nanocrystals. The crystallographic predominant plane or Miller indices were also revealed by selected area electron diffraction (SAED) on TEM. The FCC structure of Ag and Cu is shown in larger lattice volumes compared to the HCP structure of Ti and prefer oriented. The degree of crystallinity of Ti, Cu and Ag nanocrystalline materials was observed at 90.0%, 98.0% and 100.0% respectively. This quantitative comparison provides valuable insights into the structural property relationships in these nanocrystals, enabling rational design strategies for optimizing their performance in various functional applications.

High-temperature resistance performance of silica aerogel composites through fiber reinforcement

Aiming to meet the fireproof requirements for bridges, three fiber/silica aerogel composites were fabricated using basalt fiber, a composite of basalt fiber and high silica glass fiber, and high silica glass fiber as the matrix. The dimensional, structural, mechanical, and thermal insulation stability of these composites under high-temperature heating ranging from 800 °C to 1000 °C were systematically studied. Upon high-temperature heating, the fracture and deformation basalt fiber occurred, leading to the breakage of the fiber skeleton and the aerogel integrity. This resulted in significant densification and a consequent decrease in porosity in the heated basalt fiber/aerogel composite and basalt fiber-high silica glass fiber/silica aerogel composite. Crystallization of basalt fiber began after heating to 800 °C and fully completed at 1000 °C. Besides, part of the high silica glass fiber in the basalt fiber-high silica glass fiber/silica aerogel composite crystallized at 900 °C and 1000 °C. These variations in micro-macro structures and phase compositions led to a substantial degradation of mechanical property and thermal insulation performance in the composites containing basalt fiber. In sharp contrast, the fiber skeleton and aerogel integrity remained relatively stable under high-temperature heating, enabling a synergistic thermal insulation effect of fiber and aerogel. The integrated fiber skeleton reduced the radiative thermal conductivity of the aerogel, while the unbroken aerogel protected the fiber from crystallization. Consequently, the mechanical property and thermal insulation performance of the high silica glass fiber/silica aerogel composite remained stable after high-temperature heating. The ultimate tensile strength and thermal conductivity of the pristine and 1000 °C-heated high silica glass fiber/silica aerogel composite were 0.74 MPa and 0.53 MPa, 0.0213 W/(m·K), and 0.0279 W/(m·K), respectively. This novel composite, exhibiting low thermal conductivity, high strength, excellent thermal stability, is expected to be a desirable candidate for bridge fireproof applications.

Ultra-corrosion-resistant aluminum alloys achieved by femtosecond laser complete remediation of microarc oxidation defects

Microarc oxidation (MAO) is a widely employed technology for the corrosion protection of metal surfaces due to the formation of thick-layer ceramic substances. However, its practical effectiveness is strictly limited by the inevitable concomitant generation of numerous microscale pores/cracks on the oxidation surface to directly expose the substrate materials. As concerning this problem, we here introduced a novel method of the femtosecond laser irradiation to completely eliminate the above MAO defects on aluminum alloys, which consequently modulates the passivation layer into the dense and the superhydrophobic. Meanwhile, with the deep insights into the phase composition variations of the oxide layer, we can find that the laser treatments enable the development of both γ-Al2O3 and α-Al2O3 nanocrystallines with embedment in the amorphous substances to significantly improve the chemical stability of materials. Such laser modifications eventually result in the ultra-corrosion-resistant surface of aluminum alloys, with the measured corrosion current density of 1.46 × 10-13 A/cm2 as well as the impedance value over 112 GΩ∙cm2, about two orders of magnitude enhancement in the anticorrosion compared to the initial MAO sample.

Study of biphasic calcium phosphate (BCP) ceramics of tilapia fish bones by age

Biphasic calcium phosphate (BCP), consisting of bioceramics such as HAp + β-TCP and Ca10(PO4)6(OH)2 + Ca3(PO4)2, is a popular choice for optimizing performance due to its superior biological reabsorption and osseointegration. In this study, BCP was produced by calcining the bones of tilapia fish (Oreochromis niloticus) reared in net cages and slaughtered at an age ranging from 15 to 420 days. The bones were cleaned and dried, calcined at 900 °C for 8 h, and then subjected to high-energy grinding for 3 h to produce BCP powders. After the calcination process, the crystalline phase’s hydroxyapatite (HAp) and/or beta-tricalcium phosphate (β-TCP) were present in the composition of the bioceramic. The age-dependent variation in phase composition was confirmed by complementary vibrational spectroscopy techniques, revealing characteristic peaks and bands of the bioceramic. This variation was marked by an increase in HAp phase and a decrease in β-TCP phase. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) from 25 to 1400 °C showed the characteristic mass losses of the material, with a greater loss observed for younger fish, indicating the complete removal of organic components at temperatures above 600 °C. Comparison of the results obtained by X-Ray Diffraction (XRD) and Rietveld refinement with Raman spectroscopy showed excellent agreement. These results showed that with temperature and environment control and adequate fish feeding, it is possible to achieve the desired amounts of each phase by choosing the ideal age of the fish. This bioceramic enables precise measurement of HAp and β-TCP concentrations and Ca/P molar ratio, suitable for medical orthopedics and dentistry.

Compressibility effects on cavity dynamics and shock waves in high-speed water entry

The importance of high-speed water entry is acknowledged within the defense industry. This study numerically investigates the water entry of a high-speed rectangle projectile, focusing on cavity dynamics and shock wave generation. A computational model is employed to accurately simulate the intricate fluid dynamics of compressible multiphase flows. This model integrates a dual-phase flow algorithm with a thermally sensitive Tait equation of state for the liquid phase. The primary focus lies in understanding the effects of fluid compressibility on cavity evolution and shock wave propagation across different Froude numbers. The findings reveal that compressibility induces changes in cavity formation size, leading to significant variations in phase composition within the cavity. Furthermore, compressibility enhances the air cushion effect upon surface impact, resulting in delayed water entry and concurrent reduction in projectile drag. Moreover, a prognostic model is proposed, correlating shock pressure with propagation distance, thereby validating theoretical hypotheses advanced by Lee et al. [J. Fluid Struct., 11, 819–844 (1997)].

Microstructure and Impact Toughness of Laser-Arc Hybrid Welded Joint of Medium-Thick TC4 Titanium Alloy

This study delves into the impact toughness of medium-thick (12 mm thick) titanium alloy joints crafted through a multi-layer, multi-pass welding technique that blends laser-arc (MIG) hybrid welding technology. Microstructural scrutiny, employing optical microscopy, SEM and TEM, unveils a consistent composition across weld passes, with prevailing α/α′ phases interspersed with some β phase, resulting in basket-weave structures primarily dominated by acicular α′ martensite. However, upper regions exhibit Widmanstatten microstructures, potentially undermining joint toughness. Hardness testing indicates higher values in cosmetic layers (~420 HV) compared to backing layers and bending tests manifest superior toughness in lower joint regions, attributed to smaller grain sizes induced by repetitive welding thermal cycles. Impact toughness assessment unveils diminished values in the weld metal (WM) compared to the heat-affected zone (HAZ) and base material (BM), amounting to 91.3% of the base metal’s absorption energy. This decrement is ascribed to heightened porosity in upper regions and variations in grain size and phase composition due to multi-layer, multi-pass welding. Microstructural analysis proximal to failure sites suggests one mechanism wherein crack propagation is impeded by the β phase at acute crack angles. In essence, this study not only underscores the practicality of laser-MIG hybrid welding for medium-thick TC4 alloy plates but also underscores the reliability of joint mechanical properties.

Investigation of sensing performances of thick-film resistors sintered on fluorophlogopite glass-ceramic substrates

Strain gauges made of thick-film resistors (TFRs) offer a promising solution for monitoring the structural health of civil engineering projects, owing to their exceptional durability and stability. To address the issue of strain mismatch between alumina substrates and concrete materials, fluorophlogopite glass-ceramic (FGC), which has a low elastic modulus and good machinability, was utilized as a substrate for thick-film resistors. Compatibility between resistor pastes and substrates should be considered, as the substrate can significantly impact the performance of thick-film resistors. TFRs with varying concentrations of RuO2 were screen printed and fired at different temperatures on both FGC and 96% Al2O3 (as a control) substrates. The sheet resistivity, temperature coefficient of resistance (TCR), and gauge factor (GF) of TFRs were evaluated. The strain sensing performances of TFRs on FGC evaluated under compressive loading. The results indicate that TFRs on FGC substrates exhibit higher hot TCRs, lower sheet resistivities, and lower gauge factors than those on Al2O3 substrates under typical firing conditions of 850°C for 10 minutes. As the concentration of RuO2 increases, the differences in properties between TFRs on the two substrates become less pronounced. Microstructural analyses of the interface between the resistor layer and substrate indicate that changes in properties of TFRs on FGC substrates are primarily attributed to variations in RuO2 concentration and glass phase composition, which result from interactions between the resistor layer and FGC substrate. The interaction between the FGC substrate and the resistor layer can be significantly alleviated by lowering the firing temperature from 850°C to 750°C, resulting in TFRs on FGC substrates with properties comparable to those on alumina substrates. The TFRs on FGC exhibit favorable sensitivity, linearity, repeatability, and hysteresis within the input compression strain range of 0–3043με, thus showcasing significant potential for application in structural health monitoring (SHM) in civil engineering.

Ordered Phase Distribution of Quasi‐2D Perovskites Controlled by a Supramolecular Approach Enables Efficient Blue Light‐Emitting Diodes

AbstractQuasi‐2D perovskites demonstrate exceptional luminescent properties, mainly attributed to heightened radiative recombination facilitated by the energy transfer process among spontaneous quantum‐well structures featuring varied n‐value distributions. However, the rapid crystallization process often induces uncontrolled variations in phase composition, characterized by distinct “n” values, leading to suboptimal energy transfer efficiency. In this study, an innovative supramolecular strategy utilizing cryptand is introduced as an additive to regulate the phase distribution within quasi‐2D perovskite films. Cryptand effectively inhibited the aggregation of PEA+ and the formation of unsaturated Pb‐X coordination compounds, thereby suppressing the generation of low‐“n” phases. This intervention resulted in a continuous series of ordered intermediate phases with higher “n” values. The graded electronic structure facilitated efficient energy transfer from low‐“n” to high‐“n” phases, promoting effective radiation recombination. As a result, the optimized PeLEDs emitting at 490 nm demonstrated a remarkable external quantum efficiency (EQE) enhancement to 10.16%, compared to the reference device with an EQE of 2.33%. The device also exhibited impressive spectral and operational stability. The findings establish a viable strategy for precise phase distribution regulation in quasi‐2D perovskites, offering great potential for high‐performance blue PeLEDs.

Microstructural Control of a Multi‐Phase PH Steel Printed with Laser Powder Bed Fusion

AbstractThe established approach to materials design for additive manufacturing (AM) consists of attempting to reproduce the uniform structures and properties of conventionally processed materials. While this certainly helped facilitate material certification and the rapid introduction of AM technologies in several industries, the opportunity to exploit unique features of specific AM processes to generate spatially varying microstructures–and hence novel materials, remains largely untapped. This work presents a method for manufacturing materials through laser powder bed fusion (LPBF), in which control over the spatial variation in phase composition and mechanical properties is achieved. This technique is demonstrated using 17‐4 precipitation‐hardened stainless steel (17‐4PH), by controlling spatial modulation of energy densities during printing. This results in local control of ferrite/martensite volume fractions, allowing the fabrication of metal/metal architected composites with hard/brittle regions interspersed with soft/tough regions. Local variations of ~20% in tensile strength and ~150% in elongation are achieved, with a spatial resolution of ~100 microns. The approach is general and robust, fully compatible with commercially available LPBF equipment, and applicable to virtually any multi‐phase alloy system. This work shifts the paradigm from attempting to print components with uniform properties to manufacturing alloys with controlled spatial property gradients.

Understanding secondary phase inclusion and composition variations in the microstructure design of n-type Bi 2Te 3 alloys via selective dissolution of KCl

Understanding secondary phase inclusion and composition variations in the microstructure design of n-type Bi ₂Te ₃ alloys via selective dissolution of KCl

Comprehensive analysis of the effective and intra-particle diffusion of weakly retained compounds in silica hydrophilic interaction liquid chromatography columns

A detailed analysis of intra-particle volumes and layer thicknesses and their effect on the diffusion of solutes in hydrophilic interaction liquid chromatography (HILIC) was made. Pycnometric measurements and the retention volume of deuterated mobile phase constituents (water and acetonitrile) were used to estimate the void volume inside the column, including not only the volume of the mobile phase but also part of the enriched water solvent acting as the stationary phase in HILIC. The mobile phase (hold-up) volume accessible to non-retained components was estimated using a homologous series approach. The joint analysis of the different approaches indicated the formation of enriched water layers on the hydrophobic silica mesopore walls with a thickness varying significantly with mobile phase composition. The maximal thickness of the enriched water layers, which corresponded to the minimum void volume accessible to unretained solutes, marked a transition in the retention behavior of the studied analytes. Discrepancies between deuterated solvent measurements and pycnometry were explained by the existence of an irreplaceable water layer adsorbed on the silica surface. Regarding the diffusion behavior in HILIC, peak parking experiments were used to interpret the influence of the acetonitrile content on the effective diffusion coefficient Deff. A systematic decrease in Deff and molecular diffusion Dm was observed with decreasing acetonitrile concentration, primarily attributed to variations in mobile phase viscosity. Notably, Deff/Dm remained nearly unaffected by variations in mobile phase composition. Finally, the effective medium theory was used to make a comprehensive analysis of Dpart/Dm to study the contribution to band broadening when the solute resides in the mesopores. The obtained data unveiled a curvature with a minimum corresponding to conditions of maximum water-layer thickness and retention. For the weakly retained compounds (k’ < 0.5) the Dpart/Dm-values were found to be relatively high (order of 0.35-0.5), which directly reflects the high γsDs/Dm-values that were observed (order 0.35-7).

Wetting mechanisms in the mass transfer process of CuSi3 droplets on the TC4 and 304SS multi-metal system controlled by the hybrid shielding gas atmosphere

To explore the synergistic wettability of the Ti-Cu-Fe multi-metal system, the wetting behaviors of CuSi3 droplets on the TC4 and 304SS plates during the cold metal transfer welding process in various gas atmospheres were studied in this work. The effects of Ti, Fe, Si, C, and O on the spreading dynamics of liquid Cu were analyzed in detail. The results reveal that the CO2 + Ar hybrid gas shielding atmosphere significantly affects the interfacial mass transfer. The sufficient interfacial reaction and increased element diffusion promoted the formation of Ti2Cu/TiCu multiphase microstructure at the Cu/Ti interface instead of a continuous Ti2Cu layer, and a thicker and loose Fe (s, s) layer was formed at the Cu/Fe interface. The variations of surface phase composition and the generation of inward flow weakened the wettability of CuSi3/TC4 and CuSi3/304SS systems. The dissolution of Si and surface adsorption of O decreased the σlv of liquid Cu, whereas Ti and Fe had the opposite effect. When the shielding gas changed from pure Ar to CO2 + Ar hybrid gas, the potential spreading model of the CuSi3/TC4 system changed from reaction-limited to diffusion-limited, and the wetting activation energy increased from 46 kJ/mol to 57 kJ/mol. Removing oxide film, forming Ti2Cu and diffusion of Ti controlled the wetting. Whereas for the CuSi3/304SS system, the potential spreading model changed from diffusion-limited to a molecular dynamics model. Removing oxide film, diffusion of Fe and interfacial adsorption were the dominant factors for wetting.